![]() ![]() When stimulus-response control is not fully achieved or maintained, the infant will not respond to threshold levels. As you reduce age level to 5 or 4 months of age, fewer normally developing infants can be successfully conditioned and/or can maintain performance levels long enough to produce sufficient threshold searches to justify a clinical test session. With respect to your question about age, most infants who are at least 6 months of age with good head/neck/trunk control and normal cognition can be trained to perform VRA. If the response is normal for the test stimulus (i.e., < 15 dB HL), it is better to move to another frequency or stimulus to map out a greater portion of the audiogram. ![]() To obtain the maximum number of threshold searches within a clinical session, most audiologists do not test below either 10 or 15 dB HL There is no point in spending valuable attention span jockeying for a threshold response of 0 or 5 dB HL. Much research has gone into VRA and if the infant is well conditioned (i.e., good stimulus-response control), responses may be obtained at levels very close to true threshold (within 5 to 10 dB). When the child turns toward the sound stimulus, the visual reward is typically the lighting of a three dimensional toy animal or the lighting and animation of the toy animal. For VRA, the infant is conditioned through operant conditioning techniques to turn toward the sound stimulus. The second technique is visual reinforcement audiometry (VRA). Since the advent of auditory brainstem response audiometry (ABR), this technique is rarely used in clinic to attempt to define hearing loss. BOA responses are not conditioned and will occur at varying sensation levels above threshold. For BOA, stimuli are presented and trained observers watch for a time-locked response to the sound, such as eye-widening or cessation of activity. The first, and less reliable/valid, is behavioral observation audiometry (BOA). For young infants there are two methods for behavioral hearing assessment. ![]() The consensus in pediatric audiology is that normal hearing level for the audiometric frequencies and speech awareness threshold for young infants is < 15 dB HL. ![]() Elsewhere, I have read that you should expect elevated thresholds for normal hearing infants. A related goal of the psychoacoustic investigations is to identify some of the possible contributing factors that underlie the speech understanding difficulties of older listeners.What is the consensus on pediatric behavioral hearing testing (4 months+) regarding the upper limit of normal? In other words, what is defined as a "Normal range" of response for young infants for Behavioral Observational Audiometry? I have read conflicting literature on this, some of which suggests that you should expect infants to respond similarly to adults if they have normal hearing, at 0-15 dB. Where possible, age-related alterations in processing mechanisms associated with spectral, intensive, and temporal aspects of sound are linked to known anatomical and physiological changes with age in the auditory system (see Schmiedt, Chapter 2 Canlon, Illing, and Walton, Chapter 3). This topic is explored in the present chapter by a review of recent psychoacoustic studies that were conducted to identify those auditory abilities and processes that appear to be affected by aging. Equally important are questions about the extent to which aging of the auditory system compromises listeners’ ability to process simple and complex nonspeech sounds. Some of the research needs cited are specific to speech processing and aging (see Humes and Dubno, Chapter 8) and to general aspects of cognition and audition (see Schneider, Pichora-Fuller, and Daneman, Chapter 7). An earlier comprehensive review of these problems (Committee on Hearing, Bioacoustics, and Biomechanics 1988) outlined the scope of the age-related listening difficulties and pointed to several areas of interest where information was lacking and greater study was needed. Historically, the study of human aging and hearing has focused on problems of speech perception and comprehension experienced by older listeners. ![]()
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