AIOU Solved Assignments code MSc 682 Autumn & Spring 2020 Assignment 1& 2 Course: Speech and Hearing (682) Spring 2021. AIOU past papers
ASSIGNMENT No: 1& 2
Speech and Hearing (682) MSc (2 Years)
AIOU Solved Assignment 1& 2 Code 682 Autumn & Spring 2020
Q.1 Define masking and its use in air-conduction and bone conduction tests. Also discuss rules and types of masking.
It seems reasonable to assume that sounds presented to the right ear are heard by the right ear, and that sounds presented to the left ear are heard by the left ear. However, this is not necessarily true. In fact, it is common to find that the sound being presented to one ear is actually being heard by the opposite ear. This phenomenon is called cross-hearing or shadow hearing. To avoid confusion it is customary to call the ear currently being tested the test ear (TE) and to call the opposite ear, which is the one not being tested, the nontest ear (NTE). Cross-hearing results in a false picture of the patient’s hearing. Even the possibility that the sounds being presented to the TE are really being heard by the NTE causes the outcome of a test to be suspect, at best. This chapter explains why this situation occurs, how it is recognized, and the manner in which the NTE is removed from the test.
Cross-Hearing and Interaural Attenuation
Suppose we know for a fact that a patient’s right ear is essentially normal and that his left ear is completely deaf. We would expect the audiogram to show airand bone-conduction thresholds of perhaps 0 dB HL to 10 dB HL for the right ear and “no response” symbols for both air-conduction and bone-conduction at the maximum testable levels for the left ear, as in Fig. 9.1a. However, this does not occur. Instead, the actual audiogram will be more like the one shown in Fig. 9.1b. Here the thresholds for the right ear are just as expected. On the other hand, the left air-conduction thresholds are in the 55 to 60 dB HL range, and the left bone-conduction thresholds are the same as for the right ear. How can this be if the left ear is deaf?
Cross-Hearing for Air-Conduction
Let us first address this question for the air-conduction signals. Since the patient cannot hear anything in the left ear, the level of an air-conduction test tone presented to that ear will be raised higher and higher. Eventually, the tone presented to the deaf ear will be raised so high that it can actually be heard in the opposite ear, at which point the patient will finally respond. The patient’s response to the signal directed to his deaf ear (the TE) is the result of hearing that signal in the other ear (the NTE). Thus, the left ear’s threshold curve in Fig. 9.1b is due to cross-hearing, and is often called a shadow curve.
In order for the tone to be heard in the NTE it must be possible for a signal presented to one ear to be transmitted across the head to the other ear. This phenomenon is called signal crossover. The intensity of the sound reaching the NTE is less than what was originally presented to the TE because it takes a certain amount of energy to transmit the signal across the head. The number of dB that are “lost” in the process of signal crossover is called interaural attenuation (IA) (Chaiklin 1967).
In Fig. 9.1b, the patient’s right air-conduction threshold at 1000 Hz is 10 dB HL. Even though his left ear is completely deaf, he also responded to a 1000 Hz tone presented from the left earphone at 60 dB HL. This means that the 60 dB HL tone presented to the left ear must have reached a level of 10 dB HL in the right ear. Consequently, IA at 1000 Hz in this case must be 50 dB (60 dB – 10 dB = 50 dB). Similarly, the amount of IA at 4000 Hz in this case is 55 dB (60 dB – 5 dB = 55 dB)
Crossover occurs when the signal is physically present in the opposite ear, whereas cross-hearing occurs only when it is audible. The distinction is clarified using the following example based on our hypothetical patient: The level of the 1000 Hz tone reaching this person’s right (nontest) ear will always be 50 dB less than the amount presented from the left earphone due to IA. Consider these three cases:
|dB HL at left earphone||– IA||= dB HL present at right cochlea|
|(a) 60 dB||– 50 dB||= 10 dB (at threshold)|
|(b) 80 dB||– 50 dB||= 30 dB (20 dB SL)|
|(c) 55 dB||– 50 dB||= 5 dB (5 dB below threshold)|
Fig. 9.1 (a) Imagined (incorrect) audiogram without cross-hearing for a patient who is deaf in the left ear, showing “no response” for air-conduction or bone-conduction signals. (b) Actual audiogram for such a patient, reflecting the fact that the signals presented to the left side were heard in the right ear by cross-hearing. (c) Audiogram obtained when the left thresholds are retested with masking noise in the right ear.
These three examples are shown graphically in Fig. 9.2. In (a) the tone reaches the right ear at 10 dB HL, and is heard because this is the right ear’s threshold. In (b) the tone reaches the right ear at 30 dB HL and is heard because this level is 20 dB above the right ear’s threshold (20 dB SL). In both of these cases signal crossover resulted in cross-hearing. However, the tone in (c) reaches the right ear at only 5 dB HL, which is 5 dB below threshold and is thus inaudible. Here, there is crossover because the signal is present in the NTE but there is no cross-hearing because it is below threshold.
Assuming the bone-conduction threshold remained at 10 dB HL, how would cross-hearing be affected if the IA was changed from 50 dB to another value, such as 40 dB or 60 dB? Some time with paper and pencil will reveal that the cross-hearing situation would change considerably.
Cross-Hearing for Bone-Conduction
The right and left bone-conduction thresholds are the same in Fig. 9.1b even though the right ear is normal and the left one is deaf. The implication is that the bone-conduction signal presented to the left side of the head is being received by the right ear. This should come as no surprise, since we found in Chapter 5 that a bone-conduction vibrator stimulates both cochleae about equally. From the cross-hearing standpoint, we may say that there is no interaural attenuation (IA = 0 dB) for bone-conduction. Thus, the right and left bone-conduction signals result in the same thresholds because they are both stimulating the same (right) ear.
Fig. 9.2 (a–c) Three crossover conditions (see text).
Overcoming Cross-Hearing with Masking Noise
The above example demonstrates that there are times when the NTE is (or at least may be) responding to the signals intended for the TE. How can we stop the NTE from hearing the tones being presented to the TE? First, consider an analogy from vision testing. Looking at an eye chart with two eyes is akin to the cross-hearing issue. We all know from common experience that to test one eye at a time the optometrist simply blindfolds the nontest eye. In other words, one eye is tested while the other eye is masked. In effect, we do the same thing in audiology, except that the auditory “blindfold” is a noise that is directed into the NTE. The noise in the NTE stops it from hearing the sounds being presented to the TE. Just as the nontest eye is masked by the blindfold, so is the nontest ear masked by the noise.
Returning to our example, Fig. 9.1c shows the results obtained when the air- and bone-conduction thresholds of the left (test) ear are retested with appropriate masking noise in the right (nontest) ear. The thresholds here are shown by different symbols than the ones in frames (a) and (b), to distinguish them as masked results. Because the left ear in this example is completely deaf, the masked thresholds have downward-pointing arrows indicating no response at the maximum limits of the audiometer. Notice that the masked results in frame (c) are at the same hearing levels as the ones in frame (a). The important difference is that the unmasked thresholds in frame (a) could never have actually occurred because of cross-hearing. Note the dramatic difference between the unmasked results in frame (b) and the patient’s real hearing status, revealed by the masked thresholds in frame (c).
We see that when cross-hearing occurs it is necessary to retest the TE while directing a masking noise into the NTE. The purpose of the masking noise is to prevent the NTE from hearing the tone (or other signal) intended for the TE. Thus, the issue of whether cross-hearing might be occurring is tantamount to the question, is masking (of the NTE) necessary?
Principal Mechanism of Crossover
Signal crossover (and therefore cross-hearing) for bone-conduction signals obviously occurs via a bone-conduction route, as depicted in Fig. 9.3a. It occurs because a bone-conduction signal is transmitted to both cochleae.
Because crossover for air-conduction requires a reasonably substantial signal to be produced by the earphone (recall that interaural attenuation was ~ 50 dB in the prior example), common sense seems to suggest that air-conduction signals might reach the opposite ear by an air-conduction route. This might occur by sound escaping through the earphone cushion on the test side, traveling around the head, and then penetrating the earphone cushion on the non-test side. Alternatively, earphone vibration on the test side might be transmitted via the headset to the earphone on the nontest side. In either of these two scenarios, the signal from the test side would enter the ear canal of the NTE, that is, as an air-conduction signal. As compelling as these explanations may seem, they are not correct. It has been shown repeatedly that the actual crossover route for air-conduction signals occurs principally by bone-conduction to the cochlea of the opposite ear (Sparrevohn 1946; Zwislocki 1953; Studebaker 1962), as depicted in Fig. 9.3b.
Fig. 9.3 Signal crossover and cross-hearing occur via the bone-conduction route to the opposite cochlea, as indicated by the arrows for both (a) bone-conduction and (b) air-conduction.
Interaural Attenuation for Air-Conduction
Cross-hearing of a test signal renders a test invalid. We must therefore identify cross-hearing whenever it occurs so that we can mask the NTE. The cost of failing to do so is so great that we want to employ masking every time that cross-hearing is even possible. Once we have obtained the unmasked audiogram, we are left with the following question: Is the air-conduction signal being presented to the TE great enough to cross the head and reach the bone-conduction threshold of the NTE? In other words, is this difference greater than the value of interaural attenuation? The corollary problem is to determine the IA value.
Interaural attenuation for air-conduction using supra-aural earphones typical of the type used in audiological practice has been studied using a variety of approaches (Littler, Knight, & Strange 1952; Zwislocki 1953; Liden 1954; Liden, Nilsson, & Anderson 1959a; Chaiklin 1967; Coles & Priede 1970; Snyder 1973; Smith & Markides 1981; Sklare & Denenberg 1987). Fig. 9.4 shows the mean IA values found in four of these studies, as well as the maximum and minimum amounts of IA obtained across all four studies. Average IA values are ~ 50 to 65 dB, and there is a general tendency for IA to become larger with frequency. The range of IA values is very wide, and the means are much larger than the minimum IA values. Consequently, we cannot rely on average IA values as a red flag for cross-hearing in clinical practice because many cases of cross-hearing would be missed in many patients on the lower side of the IA range. For this reason it is common practice to use minimum IA values to identify possible cross-hearing, that is, to decide when masking may be needed. As anticipated from the figure, the minimum IA value typically suggested to rule out crossover for clinical purposes is 40 dB (Studebaker 1967; Martin 1974, 1980).
Interaural Attenuation for Insert Earphones
The IA values just described are obtained using typical supra-aural audiometric earphones, such as Telephonics TDH-49 and related receivers. In contrast, insert earphones such as Etymotic ER-3A and EARtone 3A receivers provide much greater amounts of IA (Killion, Wilber, & Gudmundsen 1985; Sklare & Denenberg 1987). This occurs because the amount of IA is inversely related to the contact area between the earphone and the head (Zwislocki 1953), and the contact area between the head and earphone is much less for insert receivers than it is for supra-aural earphones. Fig. 9.5 shows some of the results obtained by Sklare and Denenberg (1987), who compared the IA produced by TDH-49 (supra-aural) and ER-3A (insert) earphones on the same subjects. They found that mean IA values were from 81 to 94+ dB up to 1000 Hz and 71 to 77 dB at higher frequencies, for insert receivers.
As already explained, we are most interested in the minimum IA values, which are shown by the bottoms of the error lines in the graph. Sklare and Denenberg found that insert receivers produced minimum IA values of 75 to 85 dB at frequencies up to 1000 Hz, and 50 to 65 dB above 1000 Hz. This is substantially greater than the minimum IA values found for the TDH-49 earphone, which ranged from 45 to 60 dB.
Fig. 9.4 Interaural attenuation values for supra-aural earphones from four representative studies. Lines with symbols are means for each study. The “minimum” and “maximum’’ lines show the smallest and largest IA values across all four studies.
Fig. 9.5 Interaural attenuation for TDH-49 (supra-aural) versus ER-3A (insert) earphones. Bars show means and error lines show ranges. Some actual values were higher than shown. (This occurred because some individual IA values were higher than the limits of the equipment.) (Based on the data of Sklare and Denenberg ).
It should be noted that the IA values just described were obtained using insert receivers that were inserted to the proper depth into the ear canal. Insert receivers produce much less IA when their insertion into the ear canal is shallow compared with deep (Killion et al 1985).
Interaural Attenuation for Bone-Conduction
It is commonly held that interaural attenuation is 0 dB for all bone-conduction signals, but this concept requires qualification. There is essentially no IA for bone-conduction signals presented by a bone-conduction vibrator using frontal placement (Studebaker 1967). However, IA for the more commonly used mastoid placement of the bone-conduction oscillator depends on the frequency being tested, and is also variable among patients (Studebaker 1964, 1967). Interaural attenuation values for bone-conduction signals presented at the mastoid are ~ 0 dB at 250 Hz and rise to ~ 15 dB at 4000 Hz (Studebaker 1967). The author’s experience agrees with others’ clinical observations that IA for bone-conduction varies among patients from roughly 0 to 15 dB at 2000 and 4000 Hz (Silman & Silverman 1991).
Recall that masking per se means to render a tone (or other signal) inaudible due to the presence of a noise in the same ear as the tone. Thus, masking the right ear means that a noise is put into the right ear, so that a tone cannot be heard in the right ear. Clinical masking is an application of the masking phenomenon used to alleviate cross-hearing. In clinical masking we put noise into the nontest ear because we want to assess the hearing of the test ear. In other words, the masking noise goes into the NTE, and the test signal goes into the TE. Also, the noise is delivered to the NTE by air-conduction, regardless of whether the TE is being tested by air- or bone-conduction. These rules apply in all but the most unusual circumstances. The kinds of masking noises used with various test signals are covered in a later section. In the meantime, it is assumed that the appropriate masking noise is always being used.
The meaning is clear when an audiologist says that she will “retest the left bone-conduction threshold with masking noise in the right ear.” However, masking terminology is usually more telegraphic. As such, it suffers from ambiguity and can be confusing to the uninitiated. It is therefore worthwhile to familiarize oneself with typical masking phrases and what these really mean. Unmasked air-conduction (or just unmasked air) refers to an air-conduction threshold that was obtained without any masking noise. Similarly, unmasked bone-conduction (or unmasked bone) means a bone-conduction threshold obtained without any masking noise. For example, unmasked right bone means the bone-conduction threshold of the right ear that was obtained without any masking noise.
Masked air-conduction (or masked air) refers to an air-conduction threshold (in the TE) that was obtained with masking noise in the opposite ear. Masked bone-conduction (masked bone) denotes a bone-conduction threshold obtained with masking noise in the NTE. Thus, masked right air is referring to the air-conduction threshold of the right ear that was obtained while masking noise was being presented to the left (nontest) ear. By the same token, masked left bone means the bone-conduction threshold of the left ear that was obtained with masking noise in the right ear.
The process of masking for air-conduction (masking for air) means to put masking noise into the NTE while testing the TE by air-conduction. Likewise, the operation of masking for bone-conduction (masking for bone) means to put masking noise into the NTE while testing the TE by bone-conduction.
Instructions for Testing with Masking
The first step in clinical masking is to explain to the patient what is about to happen and what she is supposed to do. The very idea of being tested with “noise in your ears” can be confusing to some patients, especially when they are being evaluated for the first time. The author has found that most patients readily accept the situation when they are told that putting masking noise in the opposite ear is the same as an optometrist covering one eye while testing the other.
Noises Used for Clinical Masking
What kind of noise should be used to mask the non-test ear? The answer to this question depends on the signal being masked. If the signal being masked has a wide spectrum, such as speech or clicks, then the masker must also have a wide spectrum. (The student might wish to refer back to Chapter 1 to review the relevant physical concepts.) For example, masking for speech tests commonly uses white noise (actually broadband noise), pink noise, speech-shaped noise, or multitalker babble. Speech-shaped noise has a spectrum that approximates that of the long-term spectrum of speech. Multitalker babble is made by recording the voices of many people who are talking simultaneously, resulting in an unintelligible babble.
Complex noises (e.g., sawtooth noise) composed of a low fundamental frequency along with many harmonics were also used in the past. These noises were poor and unreliable maskers, but one should be aware of them if only for historical perspective.
Pure tones can also be masked by wide-band noises, but this is not desirable. Recall from Chapter 3 that if we are trying to mask a given pure tone, only a rather limited band of frequencies in a wide-band noise actually contributes to masking that tone. This is the critical band (ratio). The parts of a wide-band noise that are higher and lower than the critical band do not help mask the tone, but they do make the noise sound louder. Thus, wide-band noise is a poor choice for masking pure tones because it is both inefficient and unnecessarily loud.
It would therefore seem that the optimal masking noises for pure tones would be critical bands. In practice, however, audiometers actually provide masking noise bandwidths that are wider than critical bands. This type of masking noise is called narrow-band noise (NBN). Audiometric NBNs may approximate bandwidths that are one-third octaves, one-half octaves, or other widths, and also vary widely in how sharply intensity falls outside the pass band (i.e., the rejection rate or steepness of the filter skirts). If an NBN is centered around 1000 Hz, then we can call this a 1000 Hz NBN; if it is centered around 2000 Hz, then it is a 2000 Hz NBN, and so forth. Table 9.1 summarizes the bandwidths for narrow-band masking noises specified by the ANSI S3.6-2010 standard.
When to Mask for Bone-Conduction
It might seem odd to discuss the bone-conduction masking rule before the one for air-conduction (AC) because this is the reverse of the order used to obtain unmasked thresholds. However, masked thresholds are tested in the opposite order, bone-conduction (BC) before AC. This is done because the rule for determining when masking is needed for air-conduction depends upon knowing the true bone-conduction thresholds. This means that if masking is needed for BC, it must be done first.
Bone-conduction testing presents us with a peculiar dilemma if we take it for granted that we always need to know which ear is actually responding to a signal. This is so because there is little if any IA for BC, so we rarely know for sure which cochlea is actually responding to a signal, no matter where the vibrator is placed. (Although mastoid placement is assumed throughout this book unless specifically indicated, it should be noted that the bone oscillator and both earphones are usually in place from the outset when forehead placement is used.)
This situation might seem to imply that masking should always be used whenever bone-conduction is tested. This approach was recommended by ANSI (2004) on the grounds that bone-conduction calibration is based on data that were obtained with masking the opposite ear.
However, this approach is not encouraged because it has several serious problems in addition to being unnecessarily conservative at the cost of wasted effort (Studebaker 1964, 1967). When bone-conduction thresholds are always tested with masking, the opposite ear will always be occluded with an earphone (both ears would probably be occluded with forehead placement). Thus, one cannot know when or where an occlusion effect occurs, or how large it is. But you need to know the size of the occlusion effect in the first place to calculate how much noise is needed for bone-conduction masking. In addition, always having the headset in place denies the clinician the ability to cross-check for bone-conduction oscillator placement errors, which cause falsely elevated bone-conduction thresholds. Also, placement problems can be clouded by an occlusion effect and/or by unwittingly attributing a higher threshold to the masking. The headset itself only exacerbates vibrator placement problems.
Another questionable technique relies on the Weber test to determine which ear is hearing a bone-conduction signal. These results are not sufficiently accurate or reliable for this purpose. Even its proponents admit that it is best to disregard unlikely Weber results (Studebaker 1967).
Because a given unmasked bone-conduction threshold could as likely be coming from either ear, a practical approach to deciding when to mask for bone-conduction is based on whether knowing which cochlea is actually responding affects how the audiogram is interpreted. In other words, when does it make a difference whether a given bone-conduction threshold is coming from one cochlea or the other?
A bone-conduction threshold should be retested with masking in the NTE whenever there is an air-bone-gap (ABG) within the test ear that is greater than 10 dB, that is, 15 dB or more, which may be written as:
ABG > 10 dB.
Because testing is done in 5 dB steps, this rule also can be stated this way: A bone-conduction threshold should be retested with masking in the NTE whenever the air-bone-gap (ABG) within the test ear is 15 dB or more, or
ABG ≥ 15 dB
This principle is shown schematically in Fig. 9.6a. This rule is consistent with the one recommended by Yacullo (1996, 2009), but differs from a stricter approach that calls for masking whenever the ABG is ≥ 10 dB (Studebaker 1964; ASHA 2005).1 The underlying concept for suggesting the less stringent masking criterion is as follows: The variability of a clinical threshold is usually taken to be ± 5 dB. Applying this principle to both the air- and bone- conduction thresholds for the same frequency allows them to be as much as 10 dB apart. Thus, for practical purposes, an ABG ≤ 10 dB is too small to be clinically relevant.
AIOU Solved Assignment 1& 2 Code 682 Autumn & Spring 2020
Q.2 Discuss different properties of sound in relation to children’s classroom experiences. Support your answer with examples.
Sound is created when something vibrates and sends waves of energy (vibration) into our ears. The vibrations travel through the air or another medium (solid, liquid or gas) to the ear. The stronger the vibrations, the louder the sound. Sounds are fainter the further you get from the sound source.
Sound changes depending on how fast or slow an object vibrates to make sound waves. Pitch is the quality of a sound (high or low) and depends on the speed of the vibrations. Different materials produce different pitches; if an object vibrates quickly we hear a high-pitched sound, and if an object vibrates slowly we hear a low-pitched sound. Sounds are usually a mixture of lots of different kinds of sound waves.
This topic is often introduced by asking the children to close their eyes and listen to the sounds they can hear in the local environment, or play a sound matching game to identify sounds where they listen to a range of sounds and identify what is making the sound. A video like this one might be used as a lesson starter:
- Teachers may use a slinky, tuning forks, ripples on a pond and science video clips to introduce the concept of sound waves/vibrations traveling through air and other materials to the ear.
- Teachers will discuss sound safety and why people working with loud noises wear ear defenders.
- Children will explore pitch and loudness using a range of music instruments from around the world, for example drums, recorders, guitars. Children will investigate how to increase the pitch by changing the tightness of a drum skin or the length of a string on a string instrument.
- Children may carry out investigations to find sound-insulating materials, for example finding the best material to make ear muffs or defenders, and learn these work because the sound doesn’t travel through some materials as well as through others.
- Children may carry out investigations to explore the distance sound will travel.
Spoken communication is uniquely human. If the sense of hearing is damaged or absent, individuals with the loss are denied the opportunity to sample an important feature of their environment, the sounds emitted by nature and by humans themselves. People who are deaf or hard-of-hearing will have diminished enjoyment for music or the sound of a babbling brook. We recognize that some deaf and hard-of-hearing children are born to deaf parents who communicate through American Sign Language. Without hearing, these children have full access to the language of their home environment and that of the deaf community. However, the majority of deaf and hard-of-hearing children are born to hearing parents. For these families, having a child with hearing loss may be a devastating situation. The loss or reduction of the sense of hearing impairs children’s ability to hear speech and consequently to learn the intricacies of the spoken language of their environment. Hearing loss impairs their ability to produce and monitor their own speech and to learn the rules that govern the use of speech sounds (phonemes) in their native spoken language if they are born to hearing parents. Consequently, if appropriate early intervention does not occur within the first 6-12 months, hearing loss or deafness, even if mild, can be devastating to the development of spoken communication with hearing family and peers, to the development of sophisticated language use, and to many aspects of educational development, if environmental compensation does not occur.
Hearing loss can affect the development of children’s ability to engage in age-appropriate activities, their functional speech communication skills, and their language skills. Before we consider the effects of hearing loss on this development, we will review briefly the extensive literature on the development of speech and language in children with normal hearing. Although the ages at which certain development milestones occur may vary, the sequence in which they occur is usually constant (Menyuk, 1972).
Infants begin to differentiate among various sound intensities almost immediately after birth and, by 1 week of age, can make gross distinctions between tones. By 6 weeks of age, infants pay more attention to speech than to other sounds, discriminate between voiced and unvoiced speech sounds, and prefer female to male voices (Nober and Nober, 1977).
Infants begin to vocalize at birth, and those with normal hearing proceed through the stages of pleasure sounds, vocal play, and babbling until the first meaningful words begin to occur at or soon after 1 year of age (Bangs, 1968; Menyuk, 1972; Quigley and Paul, 1984; Stark, 1983). Speech-like stress patterns begin to emerge during the babbling stages (Stark, 1983), along with pitch and intonational contours (Bangs, 1968; Quigley and Paul, 1984; Stark, 1983).
According to Templin (1957), most children (75 percent) can produce all the vowel sounds and diphthongs by 3 years of age; by 7 years of age, 75 percent of children are able to produce all the phonemes, with the exception of “r.” Consonant blends are usually mastered by 8 years of age, and overall speech production ability is generally adult-like by that time (Menyuk, 1972; Quigley and Paul, 1984).
Language studies have described vocabulary and grammatical development of children with normal hearing. Studies of grammatical development have focused on both word structure (e.g., prefixes and suffixes), termed “morphology,” and the rules for arranging words into sentences, termed “syntax.” Vocabulary development up to young adulthood is estimated at roughly 1,000 word families per year, with vocabulary size estimated at approximately 4,000-5,000 word families for 5-year-olds and 20,000 word families for 20-year-olds (see Schmitt, 2000, for discussion). A word family is defined as a word plus its derived and inflectional forms. Most morphological and syntactic skills are fully developed by the age of 5 years, and grammatical skills are fully developed by age 8 (Nober and Nober, 1977). By age 10 to 12, most children with normal hearing have reached linguistic maturity (Quigley and Paul, 1984). In summary, by age 4½ years, children with normal hearing are producing complex sentences. Although a majority of the speech sounds in English are mastered by age 4, and most of the grammatical categories by age 5, it is not until age 8 that a normally hearing child has fully mastered grammar and phonology and has an extensive vocabulary (Nober and Nober, 1977).
Children with Hearing Loss
A review of speech and language development in children with hearing loss is complicated by the heterogeneity of childhood hearing loss, such as differences in age at onset and in degree of loss; we review these complicating factors separately following a more general overview. Mental and physical incapacities (mental retardation, cerebral palsy, etc.) may also coexist with hearing loss. Approximately 25-33 percent of children with hearing loss have multiple potentially disabling conditions (Holden-Pitt and Diaz, 1998; McCracken, 1994; Moeller, Coufal, and Hixson, 1990). In addition, independent learning disabilities and language disabilities due to cognitive or linguistic disorders not directly associated with hearing loss may coexist (Mauk and Mauk, 1992; Sikora and Plapinger, 1994; Wolgemuth, Kamhi, and Lee, 1998). For example, Holden-Pitt and Diaz (1998) reported the following incidences of additional impairments in a group of children with some degree of hearing loss: The coexistence of other disabilities with hearing impairment may impact the way in which sensory aids are fitted or the benefit that children receive from them (Tharpe, Fino-Szumski, and Bess, 2001). A recent technical report from the American Speech-Language-Hearing Association stated that pediatric cochlear implant recipients with multiple impairments often demonstrate delayed or reduced communication gains compared with their peers with hearing loss alone (American Speech-Language-Hearing Association, 2004).
In this chapter, we focus on speech and language development in children with prelingual onset of hearing loss (before 2 years of age) without comorbidity. However, it should be kept in mind that the presence of multiple handicapping conditions may place a child at greater risk for the development of communication or emotional disorders (Cantwell, as summarized by Prizant et al., 1990). In addition, these children may require adaptations to standard testing routines to accommodate their individual capacities.
Natural acquisition of speech and spoken language is not often seen in individuals with profound hearing loss unless appropriate intervention is initiated early. One of the primary goals in fitting deaf or hard-of-hearing children with auditory prostheses (hearing aid or cochlear implant) is to improve the ease and the extent to which they can access and acquire speech and spoken language. It should be kept in mind that the children under discussion typically are not born to deaf parents; those children may acquire American Sign Language as their native language.
AIOU Solved Assignment 1& 2 Code 682 Autumn & Spring 2020
Q.3 How knowledge of speech perception theories help the speech therapist in speech development of hearing impaired children? Support your answer in view of Bamford theory.
One view of speech perception is that acoustic signals are transformed into representations for pattern matching to determine linguistic structure. This process can be taken as a statistical pattern-matching problem, assuming realtively stable linguistic categories are characterized by neural representations related to auditory properties of speech that can be compared to speech input. This kind of pattern matching can be termed a passive process which implies rigidity of processing with few demands on cognitive processing. An alternative view is that speech recognition, even in early stages, is an active process in which speech analysis is attentionally guided. Note that this does not mean consciously guided but that information-contingent changes in early auditory encoding can occur as a function of context and experience. Active processing assumes that attention, plasticity, and listening goals are important in considering how listeners cope with adverse circumstances that impair hearing by masking noise in the environment or hearing loss. Although theories of speech perception have begun to incorporate some active processing, they seldom treat early speech encoding as plastic and attentionally guided. Recent research has suggested that speech perception is the product of both feedforward and feedback interactions between a number of brain regions that include descending projections perhaps as far downstream as the cochlea. It is important to understand how the ambiguity of the speech signal and constraints of context dynamically determine cognitive resources recruited during perception including focused attention, learning, and working memory. Theories of speech perception need to go beyond the current corticocentric approach in order to account for the intrinsic dynamics of the auditory encoding of speech. In doing so, this may provide new insights into ways in which hearing disorders and loss may be treated either through augementation or therapy.
In order to achieve flexibility and generativity, spoken language understanding depends on active cognitive processing (Nusbaum and Schwab, 1986; Nusbaum and Magnuson, 1997). Active cognitive processing is contrasted with passive processing in terms of the control processes that organize the nature and sequence of cognitive operations (Nusbaum and Schwab, 1986). A passive process is one in which inputs map directly to outputs with no hypothesis testing or information-contingent operations. Automatized cognitive systems (Shiffrin and Schneider, 1977) behave as though passive, in that stimuli are mandatorily mapped onto responses without demand on cognitive resources. However it is important to note that cognitive automatization does not have strong implications for the nature of the mediating control system such that various different mechanisms have been proposed to account for automatic processing (e.g., Logan, 1988). By comparison, active cognitive systems however have a control structure that permits “information contingent processing” or the ability to change the sequence or nature of processing in the context of new information or uncertainty. In principle, active systems can generate hypotheses to be tested as new information arrives or is derived (Nusbaum and Schwab, 1986) and thus provide substantial cognitive flexibility to respond to novel situations and demands.
Active and Passive Processes
The distinction between active and passive processes comes from control theory and reflects the degree to which a sequence of operations, in this case neural population responses, is contingent on processing outcomes (see Nusbaum and Schwab, 1986). A passive process is an open loop sequence of transformations that are fixed, such that there is an invariant mapping from input to output (MacKay, 1951, 1956). Figure 1A illustrates a passive process in which a pattern of inputs (e.g., basilar membrane responses) is transmitted directly over the eighth nerve to the next population of neurons (e.g., in the auditory brainstem) and upward to cortex. This is the fundamental assumption of a number of theories of auditory processing in which a fixed cascade of neural population responses are transmitted from one part of the brain to the other (e.g., Barlow, 1961). This type of system operates the way reflexes are assumed to operate in which neural responses are transmitted and presumably transformed but in a fixed and immutable way (outside the context of longer term reshaping of responses). Considered in this way, such passive processing networks should process in a time frame that is simply the sum of the neural response times, and should not be influenced by processing outside this network, functioning something like a module (Fodor, 1983). In this respect then, such passive networks should operate “automatically” and not place any demands on cognitive resources. Some purely auditory theories seem to have this kind of organization (e.g., Fant, 1962; Diehl et al., 2004) and some more classical neural models (e.g., Broca, 1865; Wernicke, 1874/1977; Lichtheim, 1885; Geschwind, 1970) appear to be organized this way. In these cases, auditory processes project to perceptual interpretations with no clearly specified role for feedback to modify or guide processing.
By contrast, active processes are variable in nature, as network processing is adjusted by an error-correcting mechanism or feedback loop. As such, outcomes may differ in different contexts. These feedback loops provide information to correct or modify processing in real time, rather than retrospectively. Nusbaum and Schwab (1986) describe two different ways an active, feedback-based system may be achieved. In one form, as illustrated in Figure 1B, expectations (derived from context) provide a hypothesis about a stimulus pattern that is being processed. In this case, sensory patterns (e.g., basilar membrane responses) are transmitted in much the same way as in a passive process (e.g., to the auditory brainstem). However, descending projections may modify the nature of neural population responses in various ways as a consequence of neural responses in cortical systems. For example, top-down effects of knowledge or expectations have been shown to alter low level processing in the auditory brainstem (e.g., Galbraith and Arroyo, 1993) or in the cochlea (e.g., Giard et al., 1994). Active systems may occur in another form, as illustrated in Figure 1C. In this case, there may be a strong bottom-up processing path as in a passive system, but feedback signals from higher cortical levels can change processing in real time at lower levels (e.g., brainstem). An example of this would be the kind of observation made by Spinelli and Pribram (1966) in showing that electrical stimulation of the inferotemporal cortex changed the receptive field structure for lateral geniculate neurons or Moran and Desimone’s (1985) demonstration that spatial attentional cueing changes effective receptive fields in striate and extrastriate cortex. In either case, active processing places demands on the system’s limited cognitive resources in order to achieve cognitive and perceptual flexibility. In this sense, active and passive processes differ in the cognitive and perceptual demands they place on the system.
Although the distinction between active and passive processes seems sufficiently simple, examination of computational models of spoken word recognition makes the distinctions less clear. For a very simple example of this potential issue consider the original Cohort theory (Marslen-Wilson and Welsh, 1978). Activation of a set of lexical candidates was presumed to occur automatically from the initial sounds in a word. This can be designated as a passive process since there is a direct invariant mapping from initial sounds to activation of a lexical candidate set, i.e., a cohort of words. Each subsequent sound in the input then deactivates members of this candidate set giving the appearance of a recurrent hypothesis testing mechanism in which the sequence of input sounds deactivates cohort members. One might consider this an active system overall with a passive first stage since the initial cohort set constitutes a set of lexical hypotheses that are tested by the use of context. However, it is important to note that the original Cohort theory did not include any active processing at the phonemic level, as hypothesis testing is carried out in the context of word recognition. Similarly, the architecture of the Distributed Cohort Model (Gaskell and Marslen-Wilson, 1997) asserts that activation of phonetic features is accomplished by a passive system whereas context interacts (through a hidden layer) with the mapping of phonetic features onto higher order linguistic units (phonemes and words) representing an interaction of context with passively derived phonetic features. In neither case is the activation of the features or sound input to linguistic categorization treated as hypothesis testing in the context of other sounds or linguistic information. Thus, while the Cohort models can be thought of as an active system for the recognition of words (and sometimes phonemes), they treat phonetic features as passively derived and not influenced from context or expectations.
This is often the case in a number of word recognition models. The Shortlist models (Shortlist: Norris, 1994; Shortlist B: Norris and McQueen, 2008) assume that phoneme perception is a largely passive process (at least it can be inferred as such by lack of any specification in the alternative). While Shortlist B uses phoneme confusion data (probability functions as input) and could in principle adjust the confusion data based on experience (through hypothesis testing and feedback), the nature of the derivation of the phoneme confusions is not specified; in essence assuming the problem of phoneme perception is solved. This appears to be common to models (e.g., NAM, Luce and Pisoni, 1998) in which the primary goal is to account for word perception rather than phoneme perception. Similarly, the second Trace model (McClelland and Elman, 1986) assumed phoneme perception was passively achieved albeit with competition (not feedback to the input level). It is interesting that the first Trace model (Elman and McClelland, 1986) did allow for feedback from phonemes to adjust activation patterns from acoustic-phonetic input, thus providing an active mechanism. However, this was not carried over into the revised version. This model was developed to account for some aspects of phoneme perception unaccounted for in the second model. It is interesting to note that the Hebb-Trace model (Mirman et al., 2006a), while seeking to account for aspects of lexical influence on phoneme perception and speaker generalization did not incorporate active processing of the input patterns. As such, just the classification of those inputs was actively governed.
This can be understood in the context schema diagrammed in Figure 1. Any process that maps inputs onto representations in an invariant manner or that would be classified as a finite-state deterministic system can be considered passive. A process that changes the classification of inputs contingent on context or goals or hypotheses can be considered an active system. Although word recognition models may treat the recognition of words or even phonemes as an active process, this active processing is not typically extended down to lower levels of auditory processing. These systems tend to operate as though there is a fixed set of input features (e.g., phonetic features) and the classification of such features takes place in a passive, automatized fashion.
By contrast, Elman and McClelland (1986) did describe a version of Trace in which patterns of phoneme activation actively changes processing at the feature input level. Similarly, McClelland et al. (2006) described a version of their model in which lexical information can modify input patterns at the subphonemic level. Both of these models represent active systems for speech processing at the sublexical level. However, it is important to point out that such theoretical propositions remain controversial. McQueen et al. (2006) have argued that there are no data to argue for lexical influences over sublexical processing, although Mirman et al. (2006b) have countered this with empirical arguments. However, the question of whether there are top-down effects on speech perception is not the same as asking if there are active processes governing speech perception. Top-down effects assume higher level knowledge constrains interpretations, but as indicated in Figure 1C, there can be bottom-up active processing where by antecedent auditory context constrains subsequent perception. This could be carried out in a number of ways. As an example, Ladefoged and Broadbent (1957) demonstrated that hearing a context sentence produced by one vocal tract could shift the perception of subsequent isolated vowels such that they would be consistent with the vowel space of the putative speaker. Some have accounted for this result by asserting there is an automatic auditory tuning process that shifts perception of the subsequent vowels (Huang and Holt, 2012; Laing et al., 2012). While the behavioral data could possibly be accounted for by such a simple passive mechanism, it might also be the case the auditory pattern input produces constraints on the possible vowel space or auditory mappings that might be expected. In this sense, the question of whether early auditory processing of speech is an active or passive process is still a point of open investigation and discussion.
It is important to make three additional points in order to clarify the distinction between active and passive processes. First, a Bayesian mechanism is not on its own merits necessarily active or passive. Bayes rule describes the way different statistics can be used to estimate the probability of a diagnosis or classification of an event or input. But this is essentially a computation theoretic description much in the same way Fourier’s theorem is independent of any implementation of the theorem to actually decompose a signal into its spectrum (cf. Marr, 1982). The calculation and derivation of relevant statistics for a Bayesian inference can be carried out passively or actively. Second, the presence of learning within a system does not on its own merits confer active processing status on a system. Learning can occur by a number of algorithms (e.g., Hebbian learning) that can be implemented passively. However to the extent that a system’s inputs are plastic during processing, would suggest whether an active system is at work. Finally, it is important to point out that active processing describes the architecture of a system (the ability to modify processing on the fly based on the processing itself) but not the behavior at any particular point in time. Given a fixed context and inputs, any active system can and likely would mimic passive behavior. The detection of an active process therefore depends on testing behavior under contextual variability or resource limitations to observe changes in processing as a consequence of variation in the hypothesized alternatives for interpretation (e.g., slower responses, higher error rate or confusions, increase in working memory load).
Understanding speech perception as an active process suggests that learning or plasticity is not simply a higher-level process grafted on top of word recognition. Rather the kinds of mechanisms involved in shifting attention to relevant acoustic cues for phoneme perception (e.g., Francis et al., 2000, 2007) are needed for tuning speech perception to the specific vocal characteristics of a new speaker or to cope with distortion of speech or noise in the environment. Given that such plasticity is linked to attention and working memory, we argue that speech perception is inherently a cognitive process, even in terms of the involvement of sensory encoding. This has implications for remediation of hearing loss either with augmentative aids or therapy. First, understanding the cognitive abilities (e.g., working memory capacity, attention control etc.) may provide guidance on how to design a training program by providing different kinds of sensory cues that are correlated or reducing the cognitive demands of training. Second, increasing sensory variability within the limits of individual tolerance should be part of a therapeutic program. Third, understanding the sleep practice of participants using sleep logs, record of drug and alcohol consumption, and exercise are important to the consolidation of learning. If speech perception is continuously plastic but there are limitations based on prior experiences and cognitive capacities, this shapes the basic nature of remediation of hearing loss in a number of different ways.
Finally, we would note that there is a dissociation among the three classes of models that are relevant to understanding speech perception as an active process. Although cognitive models of spoken word processing (e.g., Cohort, TRACE, and Shortlist) have been developed to include some plasticity and to account for different patterns of the influence of lexical knowledge, even the most recent versions (e.g., Distributed Cohort, Hebb-TRACE, and Shortlist B) do not specifically account for active processing of auditory input. It is true that some models have attempted to account for active processing below the level of phonemes (e.g., TRACE I: Elman and McClelland, 1986; McClelland et al., 2006), these models not been related or compared systematically to the kinds of models emerging from neuroscience research. For example, Friederici (2012) and Rauschecker and Scott (2009) and Hickok and Poeppel (2007) have all proposed neurally plausible models largely around the idea of dorsal and ventral processing streams. Although these models differ in details, in principle the model proposed by Friederici (2012) and Rauschecker and Scott (2009) have more extensive feedback mechanisms to support active processing of sensory input. These models are constructed in a neuroanatomical vernacular rather than the cognitive vernacular (even the Hebb-TRACE is still largely a cognitive model) of the others. But both sets of models are notable for two important omissions.
First, while the cognitive models mention learning and even model it, and the neural models refer to some aspects of learning, these models do not relate to the two-process learning models (e.g., complementary learning systems (CLS; McClelland et al., 1995; Ashby and Maddox, 2005; Ashby et al., 2007)). Although CLS focuses on episodic memory and Ashby et al. (2007) focus on category learning, two process models involving either hippocampus, basal ganglia, or cerebellum as a fast associator and cortico-cortical connections as a slower more robust learning system, have garnered substantial interest and research support. Yet learning in the models of speech recognition has yet to seriously address the neural bases of learning and memory except descriptively.
AIOU Solved Assignment 1& 2 Code 682 Autumn & Spring 2020
Q.4 Hearing aid has impact on life of hearing impaired children. In your view how this technology can help a teacher of deaf in educational management of hearing impaired children.
The ability of an individual to carry out auditory tasks in the real world is influenced not only by his or her hearing abilities, but also by a multitude of situational factors, such as background noise, competing signals, room acoustics, and familiarity with the situation. Such factors are important regardless of whether one has a hearing loss, but the effects are magnified when hearing is impaired. For example, when an individual with normal hearing engages in conversation in a quiet, well-lit setting, visual information from the speaker’s face, along with situational cues and linguistic context, can make communication quite effortless. In contrast, in a noisy environment, with poor lighting and limited visual cues, it may be much more difficult to carry on a conversation or to give and receive information. A person with hearing loss may be able to function very well in the former situation but may not be able to communicate at all in the latter.
The majority of those with hearing loss acquire it later in life at a time following the acquisition of spoken language. The prevalence is particularly high among those who are over 65 years of age and among those who have been exposed to noise. Because hearing loss tends to disrupt interpersonal communication and to interfere with perception of meaningful environmental sounds, some individuals experience significant levels of distress as a result of their hearing problems. For example, some express embarrassment and self-criticism when they have difficulty understanding others or when they make perceptual errors. Others have difficulty accepting their hearing loss and are unwilling to admit their hearing problems to others. Anger and frustration can occur when communication problems arise, and many individuals experience discouragement, guilt, and stress related to their hearing loss. These negative reactions are also associated with reports of negative attitudes and uncooperative behaviors of others (Demorest and Erdman, 1989).
Interestingly, the association between degree of hearing loss and psychosocial adjustment to hearing loss per se is not strong (Erdman and Demorest, 1998). Individuals with virtually identical audiograms and clinical test results may differ greatly in their self-reported adjustment problems. This finding is not unique to the impact of hearing loss on psychosocial adjustment; low (negative) correlations between severity of impairment and degree of psychosocial adjustment have been found repeatedly in the disability literature for a wide variety of health-related problems.
Given the high variability in how individuals adjust to their hearing problems, it is not surprising that hearing loss does not seem to affect basic personality structure (Thomas, 1984). Although many adults are resilient, acquired hearing difficulties are nevertheless responsible for a high level of general psychological distress for a significant number of people due in part to isolation, loneliness, and withdrawal (Meadow-Orlans, 1985). This distress, which may be manifested in heightened anxiety, depression, sleep disturbance, and the like, is observed not only among those who seek audiological evaluation, but also among those reluctant to acknowledge a hearing problem (Hallberg and Barrenas, 1995; Hetu, Riverin, Getty, Lalande, and St-Cyr, 1990; Hetu, Riverin, Lalande, Getty, and St-Cyr, 1988) and among those who have already acquired hearing aids (Thomas, 1984, 1988). This psychological distress can significantly impact the family or significant others as well as the individual (Schein, Bottum, Lawler, Madory, and Wantuch, 2001).
Similarly to what has been found for psychosocial adjustment, studies to date have consistently demonstrated that there is no overall association between hearing loss and psychopathology. Rosen (1979) has confirmed this for individuals with acquired hearing loss, and Pollard (1994) has confirmed it from an analysis of public mental health records on deaf and hard-of-hearing individuals in the Rochester, New York, vicinity. Despite this lack of association, it is important to acknowledge that psychological distress can be a factor in adjustment difficulties.
Knutson et al. (1998) have investigated whether the use of cochlear implants can affect the social adjustment of those with acquired hearing loss. In a study of psychological change over 54 months of cochlear implant use by 37 postlingually deafened adults, the researchers used standard psychological measures of affect, social function, and personality prior to implantation, and then at regularly scheduled intervals after implantation, to assess the impact of audiological benefit. There was evidence of significant improvement on measures of loneliness, social anxiety, paranoia, social introversion, and distress. To a lesser extent, improvement was also noted for depression. Improvement of marital distress and assertiveness took comparatively longer to emerge. One caveat is that because of the complexities of individual life issues and personality attributes, it is not possible to attribute the improvement in psychological measures solely to the influence of audiological benefits. How well the improvement noted on self-report measures translates into actual social and job situations has not been determined.
Untreated hearing loss causes delays in the development of speech and language, and those delays then lead to learning problems, often resulting in poor school performance.
Unfortunately, since poor academic performance is often accompanied by inattention and sometimes poor behavior, children with hearing loss are often misidentified as having learning disabilities such as ADD and ADHD.
According to the American Speech-Language Hearing Association (ASHA), children who have mild to moderate hearing loss but do not get help are very likely to be behind their hearing peers by anywhere from one to four grade levels.
And for those with more severe hearing loss, intervention services are even more crucial; those who do not receive intervention usually do not progress beyond the third-grade level.
Frustration and confusion can also play a big part in poor academic performance. Though he might have perfectly normal speech, a child with only mild hearing loss can still have trouble hearing a teacher from a distance or amid background noise. Imagine the difficulty and confusion of not being able to hear the high-frequency consonants that impart meaning in the English language (ch, f, k, p, s, sh, t and th) and you can begin to understand some of the academic struggles a child with hearing loss faces on a daily basis. “Chick” and “thick” may sound identical to a child with hearing loss, for example.
In addition to academic struggles in school, children with hearing loss can also experience trouble socially. Communication is vital to social interactions and healthy peer relationships; without the ability to communicate effectively they often experience feelings of isolation and unhappiness.
If a child with hearing loss is excluded from social interactions or is unwilling to participate in group activities due to fear of embarrassment, the result is that she can become socially withdrawn, leading to further unhappiness. Children with hearing loss are also slower to mature socially, which hinders peer relationships.
Teachers are in a unique position to help students by arming themselves with the knowledge as to how a student with a hearing loss receives and understands information, as well as comprehensive knowledge of an individual student’s capabilities and level of comprehension. Since early intervention is key, signs teachers can watch for in the classroom include:
- Inappropriate responses to questions
- Trouble following directions
- Speech problems
A child who is struggling in school, especially if she has a family history of hearing loss or has had recurring ear infections, should be seen by a hearing care professional for an evaluation.
Depending on the results a proper course of intervention can then be recommended. Intervention is crucial because a child who is supported both at school and at home has the best chance of success, academic and otherwise.
If you believe your child is suffering from hearing loss, take her to a pediatrician or your local hearing healthcare professional today. Check out our hearing care directory for one near you.
AIOU Solved Assignment 1& 2 Code 682 Autumn & Spring 2020
Q.5 Define auditory training. How storytelling and dramatic participation can be used to promote the auditory discrimination and spontaneous vocalization?
Auditory training is an intervention method used in rehabilitative audiology that aims to help individuals with hearing loss use their residual hearing maximally. It emphasizes the development of listening skills to improve the recognition and interpretation of speech sounds despite limited hearing ability.
Storytelling is one of the simplest and perhaps most compelling forms of dramatic and imaginative activity. A good place to start is by telling stories to your pupils and encouraging them to share stories with one another. All of us can become engaging storytellers with a little practice. There may also be members of staff who are particularly skilled at telling stories, or you could invite a professional storyteller (such as Hugh Lupton in the video below) into the school. Listen to each other, watch videos of storytelling and encourage the children to identify techniques they could use in their own stories.
Awareness regarding personal hygiene helps people to have a full and healthy life in personal and social contexts, and following personal hygiene instructions can help one to maintain a suitable physical, mental, and social health level and to better accomplish the necessary tasks in one’s family and society. Poor health among school children is resulted from the lack of awareness of the health benefits of personal hygiene, personal hygiene education, and increasing health knowledge are the most effective methods to prevent or reduce many of the problems in the field of health. Personal hygiene principals provide one with a suitable framework that can be used to maintain personal health throughout one’s life and early education of these principals to children at a suitable age helps in strengthening these principals in their minds.
Among various parts of the society children are one of the most important factors in improving the society’s health situation due to their important role in learning and transferring personal hygiene principals. Teaching hygienic behaviors to children and improving their awareness in regard to personal hygiene plays an important role in preventing various diseases during their lives. An important factor to consider in health education is the demographic characteristics of the target audience such as gender, age, education, social class, economical background, job, health, and housing situations and other such factors. For example, children between ages of 6 and 9 prefer learning through experience, and therefore, books can be suitable tools for their education. To this end, the educator needs to use previous experience and personal judgment to select a method which is suitable to the characteristics of the target audience. In general, there are two types of education methods: formal and informal. Informal education is usually carried out in home or society by parents and other acquaintances while formal education is the duty of the education system including preschools, elementary schools, high schools, colleges, and universities and is carried out by teachers and educators.
Storytelling and creative drama are two of the informal education methods that can indirectly increase the children’s knowledge and are thus useful for teaching personal hygiene. Storytelling includes live recitation and directing of stories in poetry or prose for listeners. The stories used in this method can be conversations, songs, rhymes, or stories presented with or without music or other helping tools. On the other hand, creative drama is a method in which the teacher recites a poetry, shows a picture, or plays a certain music for the students and then analyzes it along with the students and together they simultaneously create scenes, scenarios, characters, and conversations related to the initial material. Creative drama is an organized experience in which children recreate a problem or part of children’s literature with the help of their teacher and then analyze and discuss the play afterward. This type of play does not need scenario, décor, makeup, or audience and the audience is the players themselves. Generally, the necessary equipment for creative drama is limited and only needs a qualified supervisor and enough space for the play to take place.
Several methods have been investigated for increasing the awareness of children and adults through education in Iran and other countries. These studies include school-based methods, methods deepening on parents’ cooperation, and other traditional or indirect methods. The results of several researches show the educational programs to be effective in improving the awareness of children about personal hygiene. Furthermore, the results of some studies showed that storytelling and creative drama are effective tools for children training.
Unlike vision, human auditory sensitivity is adult-like within a few days of birth (Adelman, Levi, Linder, and Sohmer, 1990; Klein, 1984; Sininger, Abdala, and Cone-Wesson, 1997). Consequently, hearing loss degree and configuration are judged by the same standards for newborns as for adults.
The basic hearing evaluation for persons of any age is the pure-tone audiogram. Thresholds are also measured using speech stimuli. Establishing thresholds for tonal and speech stimuli by air and bone conduction using standard adult procedures is possible with children who have a developmental age of 4-5 years. Prior to that age, procedures must be modified to meet developmental demands. For all pediatric assessments, multiple-procedure test batteries are recommended to ensure the consistency of results.
Pure-tone or frequency-specific threshold tests in infants and children are classified either as physiological tests, in which a response is determined by some objectively measured change in physiological status, or behavioral tests, in which an overt response is elicited from children in response to sound and their responses are judged by an audiologist. Physiological tests do not actually measure perception of sound but can generally predict hearing thresholds or the range of hearing with a great deal of precision. The most valuable of these tests for threshold prediction for infants less than 6 months old is the ABR. A promising but as yet less proven technique for threshold prediction in these very young children is the auditory steady-state response (ASSR). Other physiological measures that correlate with hearing levels and support the test battery include tympanometry, acoustic middle ear muscle reflex, and OAEs.
However, during the 0- to 6-month age period, it is possible to obtain unconditioned responses to sound, such as a change in sucking behavior, startle reflex, or eye widening. This test paradigm is known as behavioral observation audiometry (BOA). These responses will be suprathreshold and cannot rule out mild or moderate hearing loss. BOA is nonetheless a valuable part of the test battery for infants under age 6 months to substantiate overall impressions.
Children with normal vision at the developmental level of typical 6-month-olds naturally turn their heads to find the source of an interesting sound. VRA takes advantage of that fact by reinforcing head turns with a pleasant visual stimulus, usually an animated toy that is lit to become visible for a short time following a head turn that is time-locked to the presentation of an auditory stimulus. Tones and speech can be used. The test must be administered quickly after appropriate conditioning to maintain the child’s interest. A variety of visual reinforcers can be used to elicit head turns in response to near-threshold level stimuli. VRA can be administered using insert earphones for an ear-specific response or with a bone-conduction vibrator. If a child will not tolerate earphones, the stimuli can be presented through a speaker into the sound field of a sound-treated chamber. This procedure limits the conclusions of the tests to hearing in the better ear and cannot determine a unilateral hearing loss. Generally, normally hearing 6-month-old infants will respond to stimuli of 20 dB HL or better (Widen and O’Grady, 2002).
VRA may no longer hold the interest of children who have reached the developmental status of a 2-year-old. In that case, the children’s interest can usually be maintained by involving them in a play activity. Play audiometry involves making a game of hearing sounds. Children respond to the sound presentation, for example, by dropping a block into a bucket or stacking a ring on a peg. Devices are available that dispense a tangible reward, such as a piece of candy or a token, when an appropriate response to sound is given. This is known as tangible reinforcement audiometry (TROCA). As long as the interest of the child can be maintained, these techniques will yield accurate audiometric threshold evaluations.