Richard W. Harris

Psychometrically equivalent mandarin bisyllabic speech discrimination materials spoken by male and female talkers

The purpose of this study was to develop, digitally record, evaluate, and psychometrically equate a set of Mandarin bisyllabic word lists for use in measurement of speech discrimination. Familiar bisyllabic words were digitally recorded by male and female talkers of Standard Mandarin. Percentage of correct word recognition was measured for each word at ten intensity levels (−5 to 40 dB HL) in 5 dB increments using 20 normally hearing subjects. Using logistic regression, 200 words with the steepest logistic regression slopes were included in four psychometrically equivalent word lists of 50 words each, and eight half-lists of 25 words each. To increase auditory homogeneity of the lists, the intensity of words in each list was digitally adjusted so that the threshold of each list was equal to the midpoint between the mean thresholds of the male and female half-lists. Digital recordings of the psychometrically equivalent word recognition lists are available on compact disc.

Psychometrically equivalent trisyllabic words for speech reception threshold testing in Mandarin.

The aim of this investigation was to develop, digitally record, evaluate, and equate Mandarin trisyllabic words, which could then be used to measure the SRT. A selection of 90 frequently utilized trisyllabic words were digitally recorded by male and female talkers of Standard Mandarin and presented to 20 normally hearing subjects at 13 intensity levels (−10 to 14 dB HL) in 2 dB increments. Using logistic regression, psychometric functions were then calculated for all words. Twenty-four trisyllabic words with steep psychometric function slopes were selected, and their intensities were digitally adjusted to match the mean subject PTA (3.0 dB HL). The mean slopes for the 24 selected male and female trisyllabic Mandarin Chinese words were 11.3%/dB and 12.1%/dB, respectively. Thus we developed a list of words which were homogeneous with respect to audibility and slope. Digital recordings of the psychometrically equivalent trisyllabic words are available on compact disc.

Psychometrically equivalent Russian speech audiometry materials by male and female talkers

Despite the large number of individuals who speak Russian, only a limited number of high-quality speech audiometry materials are available in a standard dialect of Russian. Thus, the purpose of this study was to develop and evaluate speech audiometry materials that can be used to measure word recognition and SRT testing in quiet for native speakers of Russian. Familiar monosyllabic and bisyllabic words were digitally recorded by male and female talkers of Russian and subsequently evaluated by native listeners. Using logistic regression, psychometric functions were then calculated for all words. Selected monosyllabic words were digitally adjusted to create word recognition lists which are relatively homogeneous with respect to audibility and psychometric slope. Speech reception threshold materials were developed by selecting twenty-five bisyllabic words with relatively steep psychometric function slopes (12.1%/dB and 9.9 %/dB) and digitally equating their intensity to match the mean PTA of the native listeners. Digital recordings of the resulting psychometrically equivalent speech audiometry materials are available on compact disc.

Effects of Reverberation and Noise on Speech Recognition by Adults with Various Amounts of Sensorineural Hearing Impairment

Speech recognition was assessed under three levels of room reverberation, each in quiet and noise, for subjects with varying amounts of sensorineural hearing impairment. The three acoustic environments were: sound suite, reverberant room with a reverberation time (T) = 0.54 s and reverberant room with T = 1.55 s. Three groups of subjects were utilized: normal hearing, mild sensorineural hearing impairment and moderate-to-severe sensorineural hearing impairment. Speech recognition ability for each of the three groups of subjects significantly differed from the other two groups for each of the three reverberant conditions. The detrimental influences of noise and reverberation increased with the magnitude of hearing impairment. In addition, there was an interaction between noise and room reverberation, where the detrimental effects of room reverberation were compounded by the addition of noise.

Development of speech reception threshold materials for speakers of Taiwan Mandarin

The aim of this research was to develop, digitally record, evaluate, and equate speech audiometry materials that can be used to measure the speech reception threshold (SRT) in quiet for native speakers of Taiwan Mandarin. Familiar trisyllabic words were digitally recorded by male and female talkers of Taiwan Mandarin and subsequently evaluated by 20 native listeners with normal hearing at 14 intensity levels (−10 to 16 dB HL) in 2 dB increments. Using logistic regression, psychometric functions were calculated for all words. Twenty-eight words with comparatively steep psychometric functions were selected and digitally adjusted to match the mean subject pure-tone average (5.0 dB HL). This resulted in a list of words that are relatively homogeneous in threshold audibility and psychometric function slope. The mean slopes for the 28 selected male and female trisyllabic Taiwan Mandarin words were 11.3%/dB and 11.7%/dB, respectively.

Influence of Masker Bandwidth on Binaural Masking Level Differences

Masking level differences (MLDs) were investigated using masking noise with 160 Hz (amplitude-modulated noise) and 600 Hz (filtered-random noise) bandwidth. One hundred normally hearing subjects received the MLD test under both types of noise. Significant differences between noise types were observed in both N0S pi and N pi S0 conditions; MLDs were larger in amplitude-modulated noise. Consideration of these differences would indicate that older MLD norms based solely on filtered-random noise are invalid for amplitude-modulated noise especially where bandwidth differences in the noise exist. Were the norms for 600-Hz-wide filtered-random noise to be applied to results of MLD testing performed using 160-Hz-wide amplitude-modulated noise, patients with lesions in the central auditory pathway might exhibit normal or borderline normal results. Clinical MLD norms established on one type of noise should not be used to interpret MLD results obtained using a different type of noise.

Hearing Aid Quality Judgments in Reverberant and Nonreverberant Environments Using a Magnitude Estimation Procedure

Speech discrimination performance utilizing CID W-22 word lists and patient preferences for hearing aids were investigated. Preference judgments were made using the magnitude estimation procedure. 10 experienced hearing aid users served as subjects. Results revealed that speech discrimination using CID W-22 words was unable to differentiate among hearing aids which possessed similar electroacoustic characteristics. In contrast, the magnitude estimation quality judgment procedure was quite effective and reliable at differentiating among the hearing aids. Further, the magnitude estimation quality judgment procedure is able to provide numerous preference judgments about each hearing aid in a relatively short time. In addition, the magnitude estimation procedure has a major advantage over the paired-comparison quality judgment procedure in that the patient is able to actually wear the hearing aid during the magnitude estimation procedure.

Vocal jitter and shimmer in stuttering

Abstract Vocal jitter and shimmer measures of the fluent phonations of 14 stutterers, 12 male and two female, were compared with jitter and shimmer measures of a group of nonstutterers matched for age and sex. Each subject phonated four vowels nine times in random order. Each phonation was sustained for at least 5 sec and was tape-recorded. The mid-3-sec portion of each recorded vowel phonation was subjected to jitter and shimmer analyses. Measures for stutterers were larger in both instances. Significant differences between stutterers and nonstutterers were obtained for shimmer measures. Differences on jitter measures were not significant. High variability in the stuttering group accounted for the nonsignificant finding in jitter measures and, in general, indicated heterogeneity among the stutterers. Findings led to the tentative conclusion that in fluent sustained phonation, stutterers demonstrate less stable control of respiratory-laryngeal dynamics than nonstutterers.

Evaluation of a hearing compensation algorithm

A new hearing compensation algorithm based on a homomorphic multiplicative AGC (automatic gain control) is evaluated and compared against commercially available digitally programmable analog hearing aids. Both quantitative (speech recognition threshold and speech discrimination) and qualitative tests (estimation of perceived quality) were used in the evaluation. The new algorithm is shown to have made significant progress in restoring normal or near normal hearing for hearing impaired individuals.

Effects of room reverberation upon hearing aid quality judgments.

Hearing-aid-processed speech recorded in reverberant and nonreverberant environments was ranked utilizing quality judgment and speech discrimination tasks. 21 normally hearing and 20 hearing-impaired listeners ranked the hearing-aid-processed speech. Quality judgments in reverberant environments may yield important information with respect to hearing aid selection. In contrast, speech discrimination rankings in a nonreverberant environment appeared to be similar to the speech discrimination rankings obtained in the reverberant condition.