Lida G. Wall

Preliminary Studies on the Use of an ABR Amplitude Projection Procedure for Hearing Aid Selection

Hearing aid selection in young nonverbal children is difficult and objective selection procedures are needed. Kiessling (Scand Audiol 1982;11:269-275; Arch Otorhinolaryngol 1983;238:233-240) has proposed an objective hearing aid selection method based on an unaided ABR amplitude projection procedure. However, Kiesslings ABR projection method is based on the assumption that ABR amplitude is directly related to the loudness of a signal--an assumption which has not been tested. This assumption was investigated in a group of ten normally hearing and three hearing-impaired listeners. The results indicated that ABR amplitude measures obtained in a single trial do not always correlate well with perceived loudness, but ABR amplitudes averaged over several trials do correlate well with estimates of perceived loudness. The hearing-impaired listeners then participated in a second phase of the investigation in which hearing aids chosen by the ABR projection procedure were compared with hearing aids chosen by more conventional methods. The results indicated that the projection procedure prescribed appropriate gain and compression characteristics for two of the three hearing-impaired listeners.

Age‐related differences in fixed versus roving AX discriminations

The present study examines age‐related differences in the discrimination of vowels and consonants (using both AX fixed and roving paradigms). Two groups of listeners—including young adults (mean age 23.9 yr) and older adults (mean age 67.8 yr)—were required to identify and/or discriminate tokens from either a [i]‐[eh] vowel continuum or a [bopen aye]–[dopen aye] consonant continuum. The two groups were matched for auditory sensitivity. As expected, for both groups consonant responses were more ‘‘categorical’’ than were vowel responses. Fixed discrimination was also better than roving discrimination (although the effect was only significant for the consonant stimuli). In terms of age differences, discrimination performance tended to be better for younger listeners in most conditions, although these differences did not reach statistical significance. However, there was a significant age by task paradigm interaction for the consonant stimuli. Although the younger listeners showed significantly poorer discrimination in the roving vs. fixed condition, there was no such difference for the older listeners. Discriminations by older listeners were also more affected by the location of the category boundaries than were those of younger listeners. [Work supported, in part, by the National Institute on Aging Grant No. 5R01 AG08353.]

Presentation level determination for CV tokens using a computer-controlled adaptive procedure

The feasibility of using a computer-controlled adaptive procedure to find maximum monotic performance for consonant-vowel (CV) stimuli was evaluated and compared to the procedure typically used to determine a performance-intensity function in two experiments. In experiment I, the computer-controlled adaptive procedure and the typical manual procedure were evaluated on 26 normally hearing listeners. Results indicated that the shape of the performance-intensity functions was similar for both procedures with the computer-controlled adaptive procedure selecting a higher presentation level. The test-retest reliability for the computer-controlled adaptive procedure was good with a mean difference on retest of 1.2 dB. In experiment II, the same procedures were evaluated using 9 sensorineural hearing impaired subjects. Again similar configuration between functions was observed. The primary advantage of the computer-controlled adaptive procedure for both subject groups is efficiency in terms of time of administration and number of CV stimuli used.

Age‐related differences in the discrimination of two‐formant transitions

In the past 3 years age‐related differences in the ability to process rapidly changing acoustic information (e.g., formant transitions) in making phonetic decisions (e.g., identification of consonants and/or vowels) have been investigated. The data obtained in these studies have been consistent with the claim that older adults as well as children show a decreased ability to process dynamic acoustic information, compared to that of young (college‐aged) adults. The present study examines age‐related differences in the discrimination of several synthesized two‐formant transition and steady‐state continua. Two continua represented a [wi]‐[w(eh)]‐[wae] continuum (differing in terms of the duration of the transition) and the last set of stimuli represented a [bɑ ]‐[dɑ ] continuum. Three groups of listeners (children 9–12 yrs, young adults 19–25 yrs, and older adults 58–71 yrs) were required to discriminate between two stimulus tokens using a version of Levitt’s up–down adaptive procedure. Significant differences...

Age‐related differences in processing dynamic acoustic cues to initial stops.

The present study examines possible age‐related differences in the ability to process rapidly changing acoustic information in the identification and discrimination of initial stop consonants. As described in Fox et al. [J. Acoust. Soc. Am. 89, 1935(A) (1991)], older adults show lower accuracy rates in identifying both consonants and vowels in so‐called ‘‘silent‐center’’ tokens. Such results are compatible with the suggestion that older listeners have greater difficulty than younger listeners in processing dynamic acoustic cues, such as those represented by consonant transitions. Two sets of stimuli were created: one set represented a 7‐step [beh]–[deh] continuum with a 40‐ms transition followed by a 150‐ms steady‐state vowel; the second set was composed of a 7‐step [beh]–[deh] continuum with the same transition followed by a 10‐ms vowel. There were two sets of normal hearing listeners including 15 listeners aged 20–24 and 15 listeners aged 60–75. There was an identification task and two AX discrimination...