Lois L. Elliott

Performance of children aged 9 to 17 years on a test of speech intelligibility in noise using sentence material with controlled word predictability.

Performance of children aged 9 to 17 years on the SPIN test (Speech Perception in Noise) is described. The 11- and 13-year-olds performed significantly poorer than 15- and 17-year-olds, and this difference occurred primarily for high-predictability sentences presented at a O-dB signal-to-babble ratio. Performance of nine-year-olds was significantly poorer than performance of 11-year-olds. Possible reasons for these differences are discussed.

Backward Masking: Monotic and Dichotic Conditions

“Backward masking” is the term used to denote the situation in which one auditory stimulus is masked by another auditory stimulus which follows it in time while in “forward masking” the temporal positions of masking and masked signals are reversed. In this study, backward and forward masking were investigated for both monotic and dichotic conditions using white noise as the masking signal and a 1000‐cps probe signal. Results indicate that monotic backward masking occurs over intervals up to 50 msec while, for the dichotic condition, backward masking occurs for intervals as long as 15 msec. Less monotic forward masking is obtained for brief masking intervals and very little dichotic forward masking is observed. These findings are considered in relationship to other experimental results.

Perception of gated, highly familiar spoken monosyllabic nouns by children, teenagers, and older adults

A forward-gating procedure, employing highly familiar monosyllabic words, was used in testing 5–7-year-old children, 15–17-year-old teenagers, and 70–85-year-old adults. Teenagers identified the words at shorter gate durations than either the children or older adults, whose identification performances were nearly identical. Teenagers gave meaningful guesses at shorter durations than children, who, in turn, gave meaningful guesses at shorter durations than adults. The oldest listeners provided the largest number of phonetic guesses, whereas teenagers gave almost none. Individual differences in auditory pure-tone sensitivity did not account for the results. It is hypothesized that both word frequency effects and temporal processing differences were responsible for the findings.

Children’s pure‐tone detection

A three-alternative, forced-choice adaptive procedure, with suitable reinforcement, is appropriate for testing auditory sensitivity in young children. Data obtained using this rigidly specified test protocol support previous findings of reduced auditory sensitivity in young children.

Changes in the Simultaneous Masked Threshold of Brief Tones

Simultaneous monotic masking of a 5‐ or 10‐msec, 1000‐cps signal by bursts of wide‐band noise of 30–1000 msec duration (70 dB SPL) changes and is dependent upon delay of the tone (Δt) relative to masker onset. The elevated masking of the tone at short Δts (overshoot) is independent of masker duration, while minimum masking occurs at delay times of 200 or 300 msec. A 500‐msec‐long, 400‐cps noise band centered at 2550 cps produces little overshoot for 10‐msec tonal signals with frequencies located within the band but considerable overshoot for frequencies just outside it. This occurs also for a 200‐cps band centered at 1270 cps but not for a 100‐cps band at 250 cps. These effects were observed for dichotic masking also. For 500‐msec bursts of wide‐band masking noise, greater overshoot occurs at higher signal frequencies than at lower. Several different psychophysical procedures produced similar results.

Development of Auditory Narrow‐Band Frequency Contours

Four experiments were performed to explore the hypothesis that time is required for the auditory system to develop steady‐state contours corresponding to stimulation by a narrow band of frequencies. Four additive and interacting phenomena appear necessary to explain the observed results: on and off effects, temporal integration of acoustic energy, temporal persistence of the excitation pattern, and time‐dependent organization of frequency contours.

Age differences in discrimination of simulated single-formant frequency transitions

We studied auditory discrimination of simulated single-formant frequency transitions that resembled portions of certain speech consonants. Significant age differences in transition discrimination occurred; both children and older adults required larger acoustic differences between transitions for discrimination than did teenagers/young adults. Longer transitions were more easily discriminated than shorter transitions by all listeners, and there were no differences between discriminations of rising and falling transitions. Teens/young adults and older adults, but not children, required larger frequency differences to discriminate frequency transitions followed by a steady-state sound than for transitions alone. There were also age differences in discrimination of steady-state sounds. These developmental-perceptual differences may help explain why children and older adults who have good pure-tone sensitivity may experience difficulty in understanding speech.

Masking of tones before, during, and after brief silent periods in noise.

Masking of a short tone (located inside or on the skirts of a narrow noise band or masked by wide‐band noise) demonstrates interactions between sets of onset and offset effects and their relation to temporal development of auditory frequency contours.

Temporal and masking phenomena in persons with sensorineural hearing loss.

Relatively few experimental investigations have studied backward or forward masking, masking level differences, or differential frequency effects in simultaneous masking among persons with hearing impairment. This is regrettable since such efforts may lead to important new understandings of auditory processes. This paper reviews available data, discusses some precautions of experimental procedure, and offers suggestions for future research directions.

Tonal Thresholds for Short‐Duration Stimuli as Related to Subject Hearing Level

The loudness threshold for pure tones varying in duration from 3–1000 msec was studied among subjects with hearing levels ranging from “normal” to severe sensorineural loss. Results showed a negative relationship between slope of the short‐duration/threshold function and hearing acuity.