William J. Kelly

Factors in the discrimination of tonal patterns. II. Selective attention and learning under various levels of stimulus uncertainty

This is the second in a series of articles in human listeners’ abilities to discriminate between word‐length tonal sequences, or ’’patterns.’’ The first article reported that frequency resolution, by highly trained listeners, is four to five times more accurate for high‐frequency, late‐occurring components of such sequences than for low−frequency early components [Watson, Kelly, and Benbasset, J. Acoust. Soc. Am. 57, 1175–1185 (l975)]. These effects, which are similar to described as ’’recognition masking’’ or ’’informational masking’’ by other authors, have now been shown to be strongly dependent on the degree of trial‐to‐trial stimulus uncertainty of the psychophysical procedure in which they are measured. When stimulus uncertainty is reduced to its psychophysical minimum, frequency resolution for any component of a tonal sequence is only slightly less accurate than for isolated tones. Previous reports of recognition masking this may reflect limitations imposed by those more dynamic parts of the sensory...

Factors in the discrimination of tonal patterns. I. Component frequency, temporal position, and silent intervals

Factors which determine the discriminability of tonal sequences, or patterns, were investigated in five experiments. The patterns were generally sequences of ten 40‐msec tonal components, which ranged in frequency from 256 to 900 Hz, or from 500 to 1500 Hz, in equi‐log intervals. Highly trained (15 to 60 h of training prior to collecting experimental data) listeners’ abilities to detect changes in the frequency of single tonal components in these patterns were measured using a same–different psychophysical method. The just‐detectable values of Δf (d′=1.0) were only slightly larger than for single 40‐msec tones presented in isolation for tonal components at the end of the temporal sequences (a ’’recency’’ effect). Performance was systematically worse for earlier components, the just‐detectable Δf increasing by four to five times from the end of the pattern to the beginning (no ’’primacy’’ effect). The ’’recency’’ effect was interpreted as a matter of later arriving components interfering with frequency res...

Noise-induced hearing loss in children

Occupational noise exposure remains the most commonly identified cause of noise‐induced hearing loss (NIHL), but potentially hazardous noise can be encountered during leisure‐time activities. NIHL in the pediatric population has received scant attention. This study focuses on 114 children and adolescents (ages 19 and under: 90.3% males) who were diagnosed as having probable NIHL on the basis of history and audiometric configuration. In 42 children the loss was unilateral, while the remaining 72 had sensorineural losses of varying configurations in the contralateral ear. The mean age of referral for evaluation was 12.7 years (range 1.2 to 19.8, SD 4.21), although 26% of these losses were diagnosed in children aged 10 years and younger. Such irreversible, but potentially preventable losses, should be given high priority on the public health agenda. Comprehensive, age‐appropriate educational programs must be developed for elementary and secondary students and their parents to acquaint them with potentially hazardous noise sources in their environment.

Fluctuating and/or progressive sensorineural hearing loss in children.

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.

Auditory brainstem response results as predictors of behavioral auditory thresholds in severe and profound hearing impairment

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 brain‐stem 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 childs cochlear implant candidacy.

High‐frequency audiometry: Test reliability and procedural considerations

This study compared the reliability of a recently developed high-frequency audiometer (HFA) [Stevens et al., J. Acoust. Soc. Am. 81, 470-484 (1987)] with a less complicated system that uses supraaural earphones (Koss system). The new approach permits calibration on an individual basis, making it possible to express thresholds at high frequencies in dB SPL. Data obtained from 50 normal-hearing subjects, ranging in age from 10-60 years, were used to evaluate the effects on reliability of threshold variance, earpiece/earphone fitting variance, and the variance associated with the HFA calibration process. Without earpiece/earphone replacement, the reliability of thresholds for the two systems is similar. With replacement, the HFA showed poorer reliability than the Koss system above 11 kHz, largely due to errors in estimating the calibration function. HFA reliability is greater for subjects with valid calibration functions over the entire frequency range. When average correction factors are applied to the Koss data in an effort to convert threshold estimates to dB SPL, individual transfer functions are not represented accurately. Thus the benefit of being able to express thresholds at high frequencies in dB SPL must be weighed against the additional source of variability introduced by the HFA calibration process.

An auditory discrimination test battery

A battery of eight auditory discrimination tests was designed to measure the primary dimension along which simple and complex sounds can be discriminated. Six of the tests, selected on the basis of data collected in an earlier 22‐subtest version of the battery [D. M. Johnson, J. K. Jensen, and C. S. Watson, J. Acoust. Soc. Am. Suppl. 1 67, S52 (1980)], use tonal stimuli: tests of frequency, intensity, and duration discrimination, using single tones, and tests of rhythm, temporal order, and tonal‐pattern discrimination using multitone sequences. Two additional tests employ speech sounds: a syllable order discrimination test and a modification of one portion‐ of a nonsense syllable identification test [J. R. Dubno and H. Levitt, J. Acoust. Soc. Am. 69, 249–261 (1981)]. The tape‐recorded tests were designed to be administered to groups of listeners in a free field, moderately low‐reverberation environment. with responses recorded on printed forms. Seventy‐two modified 2AFC trials, distributed among eight sti...

Severe versus profound sensorineural hearing loss in children: Implications for cochlear implantation†

The advent of cochlear implants for children has stimulated interest in the specific sensory deficits and communicative capabilities of children with severe or profound bilateral sensorineural hearing loss. Appropriate management of these children and their families requires an appreciation of the multifaceted developmental and educational challenges confronting deaf children, even after cochlear implantation. Evaluation results from 200 children with bilateral sensorineural deafness (63 severe/137 profound, anacusic, and fragmentary) reveal significant differences between these two subpopulations. Within the profoundly impaired group, important differences were also noted in the childrens ability to benefit from conventional amplification, depending on residual hearing at or above 1000 Hz. Strategies for assessing auditory function and aided benefit in severely and profoundly hearing‐impaired children must involve a pediatric test battery, serial evaluations, and parental cooperation/support. When selecting candidates for cochlear implantation, it is inappropriate to categorize severely hearing‐impaired children with those children having profound sensorineural losses. Even profoundly impaired populations are not homogeneous, and rehabilitation potential with conventional amplification must be determined on an individual basis, over time.

Performance differences among the intervals in forced-choice tasks

Listeners were tested on a variety of three-interval, forced-choice auditory detection and discrimination tasks. Differences in performance were frequently found among the three intervals, with best performance in the third interval, and worst in the first. This result is at odds with the common assumptions of Signal Detection Theory that signals are equally detectable no matter which interval they are presented in, and that a decision is simply made by picking the interval with the largest likelihood ratio. An experimental technique is described by which central and peripheral determinants of the interval effect might be distinguished.

Interval biases in 3AFC experiments

Performance on several three‐alternative, temporal forced‐choice discrimination tasks (3AFC) was found to vary significantly over the three possible temporal positions of the signal on each trial. First observed in a ten‐tone pattern discrimination task, this temporal‐interval effect was also found to occur in a battery of 22 detecton and discrimination tests, designed for the study of individual differences in auditory capabilities by Johnson, Jensen and Watson [J. Acoust. Soc. Am. 67, S58 (1980)]. Interval‐specific indices of d′ and β were derived by decomposition of the 3 × 3 stimulus‐by‐response matrices for each task into 2 × 2 matrices. These measures suggest that the temporal‐interval effect is typically the result of a combination of decreased sensitivity in the early intervals and relaxed‐decision criteria for the later ones. Listeners with overall high levels of auditory resolving power in the individual‐differences test battery show the least temporal‐interval effect in 3AFC tasks. This last re...