Biomedical subjects

J L Sperry

Publications and source records attributed to J L Sperry.

3 recordsLinked to original sources

PubMed1997

Word recognition performance in various background competitors.

Word recognition performance was measured for 18 normal-hearing subjects using the female talker version of the Northwestern University Auditory Test No. 6 (NU-6) in the presence of three background competitors: (1) a meaningful multitalker competing message consisting of three male and three female talkers (forward multitalker competing message [FCM]), (2) the same multitalker competing message recorded in reverse to eliminate semantic content (backward multitalker competing message [BCM]), and (3) an amplitude-modulated speech-spectrum noise (SSN) having the same long-term average spectrum and amplitude fluctuations as the meaningful multitalker competing message. The meaningful competitor had a significantly more deleterious effect on recognition performance compared to performance for the two nonmeaningful competitors. Furthermore, the nonmeaningful speech competitor produced a significantly greater degradation in performance than that for the SSN.

Adolescent↗

PubMed1994

Masking-level difference for spondaic words in 2000-msec bursts of broadband noise.

One protocol developed for the Tonal and Speech Materials for Auditory Perceptual Assessment audio compact disc was the masking-level difference (MLD) for spondaic words in which the words and broadband noise were mixed and recorded at 16 selected signal-to-noise ratios. Four words were recorded at each level. Because it was impossible to monitor the word presentations at negative signal-to-noise ratios, a different paradigm was devised in which the spondaic words were embedded in 2000-msec bursts of noise. Before the materials were finalized for the compact disc, two experiments studied the perceptual characteristics of the paradigm. Experiment I was performed to determine the characteristics of the MLD for spondaic words in 2000-msec bursts of noise at 70 dB SPL. An unexpected finding was that the mean SoNo thresholds were at signal-to-noise ratios 3-4 dB lower than previously reported spondaic word thresholds in continuous broadband noise. Experiment II examined this discrepancy with the spondaic words embedded in continuous noise and in the 2000-msec noise bursts. The results confirmed the 3-4 dB difference between thresholds for the two masker conditions. Based on the pilot data, the spondaic words embedded in 2000-msec bursts of broadband noise at signal-to-noise ratios of 0 dB to -30 dB were recorded on the compact disc in the S pi No paradigm. In the compact disc trials, which involved 120 subjects with normal hearing, the MLDs for the spondaic words recorded on the compact disc were measured on 60 subjects at each of two noise levels.(ABSTRACT TRUNCATED AT 250 WORDS)

Acoustic Stimulation↗

PubMed1994

Effects of time compression and time compression plus reverberation on the intelligibility of Northwestern University Auditory Test No. 6.

The Tonal and Speech Materials for Auditory Perceptual Assessment, Disc 1.0 audio compact disc developed in 1992 includes several sets of degraded speech materials, two of which, time compression and reverberation, are described in this paper. The digital techniques used to compress the NU No. 6 materials (female speaker) on an 80386-based computer are described, along with a series of experiments on subjects with normal hearing that document the effects of the time compression on recognition performance. Experiment I examined at 70 dB SPL the effect on word recognition of 45, 55, 65, 70, and 75 percent compressions. Experiment II developed psychometric functions for the 45, 65, and 75 percent time-compression conditions. Experiment III defined the effects that time-compression degradation (45% and 65%) plus reverberation degradation (0.3 sec) had on the recognition performance on the NU No. 6 materials. Based on the experiments, four conditions (45% compression, 65% compression, 45% compression plus 0.3-sec reverberation, and 65% compression plus 0.3-sec reverberation) were selected and recorded on the compact disc. In the compact disc trials, normative data on the four conditions were developed from 120 listeners with normal hearing.

Compact Disks↗