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Sensorineural hearing loss (SNHL) which is sudden in onset, fluctuating, and/or progressive complicates medical management, hearing aid selection, and individualized educational planning for a hearing-impaired child. In spite of multidisciplinary evaluation and intervention, a gradual decrease in auditory acuity may continue unabated in a significant number of cases. Intercurrent middle ear disease and inconsistent audiologic technique can account for threshold variation in some cases. The study population consisted of 229 children (132 boys; 97 girls) aged 1 to 19.9 years at first audiogram which revealed at least a mild degree of sensorineural hearing loss in one or both ears (35 unilateral), and who demonstrated threshold variation of 10 dB or more in at least one ear at one or more of the standard audiometric test frequencies (250, 500, 1000, 2000, 4000, and 8000 Hz) and were without concurrent middle ear disease (mean length of follow-up, 4.9 years; mean number of audiograms, 10.3). Of 365 ears demonstrating threshold variation of 10 dB or more, 22 (6%) had purely progressive losses without intercurrent upward fluctuation, 208 (57%) had fluctuating thresholds with gradually progressive losses, and 135 (37%) had intermittent threshold fluctuation without permanent deterioration. The probability of contralateral threshold fluctuation if one ear fluctuated was 0.91, while the probability of contralateral progressive SNHL if one ear progressed was 0.67. Demographic data, presumptive etiology, degree of initial SNHL, audiometric configuration, and symmetry of threshold variation were considered as potential predictors of the likelihood of threshold fluctuation and/or progression.

Pediatric cochlear implantation is restricted to patients with stable, bilateral profound sensorineural hearing losses who derive no benefit from conventional amplification. Obtaining reliable audiologic thresholds in a young child with sudden or early-onset hearing loss can be challenging. This study examines the accuracy with which auditory brainstem response evaluation can predict unaided and aided behavioral thresholds in a child with severe-to-profound hearing loss. Reliable behavioral thresholds were obtained on 119 children who had no measurable click-evoked auditory brainstem responses at instrumentation limits of 100 dB HLn. These data show that an absent auditory brainstem response at 100 dB HLn does not necessarily indicate the absence of measurable unaided hearing for test frequencies ranging from 250 Hz to 4000 Hz. Average aided thresholds of better than 60 dB were present in 43% of the children for 500, 1000, and 2000 Hz and in 53% for 500 and 1000 Hz. Therefore, the absence of a click-evoked auditory brainstem response at 100 dB HLn in a young child is not prima facie evidence of the child's cochlear implant candidacy.

Listeners' abilities to discriminate the order of two tones, of frequency 500 Hz and 500 Hz + delta f, separated by less than 5 ms, were measured in terms of threshold durations (T) for the tones. The experiment was repeated for values of delta f between 5 and 160 Hz. The relation of the duration threshold to delta f was well-described by the reciprocity equation, delta fT = K, for K = 0.16. This reciprocity corresponds to a constant overlap of the main lobes of the power spectra for the tones of about 70%-80%. Addition of a trailing context tone severely degraded the ability to discriminate temporal order, increasing the value of the reciprocity constant to approximately K = 1.8. The primary effect of the context tones was to increase the duration required for accurate discrimination, rather than to impair actual frequency resolution. Implications of these results for speech perception are discussed.