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Biomedical subjects

D M McDaniel

Publications and source records attributed to D M McDaniel.

9 recordsLinked to original sources
PubMed1999

Monosyllabic word recognition at higher-than-normal speech and noise levels.

The effects of intensity on monosyllabic word recognition were studied in adults with normal hearing and mild-to-moderate sensorineural hearing loss. The stimuli were bandlimited NU#6 word lists presented in quiet and talker-spectrum-matched noise. Speech levels ranged from 64 to 99 dB SPL and S/N ratios from 28 to -4 dB. In quiet, the performance of normal-hearing subjects remained essentially constant in noise, at a fixed S/N ratio, it decreased as a linear function of speech level. Hearing-impaired subjects performed like normal-hearing subjects tested in noise when the data were corrected for the effects of audibility loss. From these and other results, it was concluded that: (1) speech intelligibility in noise decreases when speech levels exceed 69 dB SPL and the S/N ratio remains constant; (2) the effects of speech and noise level are synergistic; (3) the deterioration in intelligibility can be modeled as a relative increase in the effective masking level; (4) normal-hearing and hearing-impaired subjects are affected similarly by increased signal level when differences in speech audibility are considered; (5) the negative effects of increasing speech and noise levels on speech recognition are similar for all adult subjects, at least up to 80 years; and (6) the effective dynamic range of speech may be larger than the commonly assumed value of 30 dB.

Adult↗
PubMed1997

Age-related changes in monosyllabic word recognition performance when audibility is held constant.

Monosyllabic word recognition was studied in 140 subjects between the ages of 20 and 90 years. The subjects were tested under a condition of fixed audibility that was achieved by presenting bandpass-filtered Northwestern University Auditory Test No. 6 (NU-6) word lists at a constant signal-to-noise ratio and limiting threshold losses at the speech frequencies to 25 dB HL. The results indicated the following: (1) Performance did not vary appreciably with age, except among subjects over 70 years. Subjects from 70 to 80 years produced modestly reduced scores (significantly below only the 30-year-old group). Those over 80 years produced significantly lower scores (than all other groups). (2) There were no significant differences in learning or test-retest reliability associated with age. (3) The performance of the oldest subjects could not be explained by differences in speech audibility. Based on these results, a strategy is proposed for correcting predicted word recognition scores for the effects of age.

Adult↗
PubMed1995

Evaluating relative speech recognition performance using the proficiency factor and rationalized arcsine differences.

This study evaluated two measures that have been used to compare the performance of particular subjects to outcomes predicted by the articulation index (Al). One measure was the proficiency factor, that is, the ratio between the Al derived from a test score and the Al derived from objective measurements of speech and noise spectra. The other measure was the difference between rationalized arcsine transforms of the observed score and the score predicted from the Al. The results indicated that rationalized arcsine differences are statistically superior to proficiency factors for comparing two sets of scores. Proficiency factors are best used to correct the Al, and thus an expected score, for the effects of subject variables that might bias the comparison. An assessment procedure that combines the strengths of both measures is described.

Computer Simulation↗
PubMed1992

Evaluation of the speech intelligibility rating (SIR) test for hearing aid comparisons.

The SIR test was created for use in hearing aid comparisons. The test protocol obtains listener judgments of the intelligibility of connected speech passages. This study was conducted to evaluate the effectiveness of the SIR test in differentiating among hearing aids. Specific research questions were (a) Is the sensitivity of the SIR test sufficient for differentiating among very similar and slightly dissimilar hearing aids? (b) Does the SIR test result in reliable hearing aid rankings? and (c) What are the effects of using shortened connected speech passages? Ten listeners with hearing impairments rated the intelligibility of both full-length and shortened SIR test passages while wearing each of four individually selected hearing aids representing three different frequency/gain prescriptions. Results suggested that the SIR test is capable of differentiating among slightly dissimilar hearing aids and that hearing aid rankings resulting from speech intelligibility ratings were reliable. The decision to use full-length or shortened SIR test passages depends on the outcome the user wishes to maximize. Under the conditions used in this study, maximum sensitivity was achieved with ratings from five shortened passages, whereas maximum reliability was obtained with three full-length passages.

Adult↗
PubMed1990

Coping with dysphoria: gender differences in college students.

This study examined gender differences in how college students cope with dysphoria on their own. Thirty-five male and female college students who reported experiencing serious dysphoria within the past year were interviewed about the coping techniques they used. Compared to women, men made greater use of relaxation, self-reward, and situation changes. Men also employed more coping techniques than did women. For women, maintaining a faith in their own improvement was correlated significantly with less dysphoria. For men, experiencing changes in their lives and putting work into the techniques were correlated significantly with less dysphoria. For both sexes, keeping anger in was correlated significantly with more dysphoria.

Adaptation, Psychological↗
PubMed1989

Development of the Speech Intelligibility Rating (SIR) test for hearing aid comparisons.

The Speech Intelligibility Rating (SIR) Test has been developed for use in clinical comparisons of hearing aid conditions. After listening to a short passage of connected speech, subjects generate a rating proportional to its intelligibility using an equal-appearing interval scale from 0 to 10. Before test passages are presented, the signal-to-babble ratio (SBR) is adjusted to a level that elicits intelligibility ratings of 7-8 for a "setup" passage. Then, with SBR held constant, three or more test passages are rated and the results averaged for each aided condition. This paper describes the generation of recorded test materials and their investigation using normally hearing listeners. Based on these data, a critical difference of about 2 scale intervals is recommended. A future paper will deal with results for hearing-impaired subjects.

Hearing Aids↗
PubMed1986

Reference equivalent threshold levels for pure tones and 1/3-oct noise bands: insert earphone and TDH-49 earphone.

Reference equivalent threshold sound pressure levels (RETSPLs) were determined for 20 subjects for pure tones and 1/3-oct noise bands. Two transducers were used: a Telephonics TDH-49 earphone mounted in an MX-41/AR cushion, and a Danavox SMW insert earphone coupled to an "HA-2" earmold. RETSPLs for pure tones transduced by the TDH-49 earphone were very similar to those published previously. For each transducer, RETSPLs for 1/3-oct noise bands were essentially identical to the RETSPLs for pure tones near the center of each band. Applications for threshold testing using the insert earphone and/or 1/3-oct noise bands are discussed.

Adult↗
PubMed1984

Intelligibility ratings of continuous discourse: application to hearing aid selection.

Twelve normal-hearing subjects rated the intelligibility of 35-s, hearing-aid-processed continuous discourse (CD) passages. Three talkers (two male, one female), four hearing aids, and two signal-to-babble (S/B) ratios were used in a completely crossed design. Research questions concerned: (1) ability of listeners to rate intelligibility, (2) sensitivity of hearing aid rankings were based on intelligibility ratings for three CD passages per instrument, and (3) dependence of hearing aid rankings on (a) S/B ratio, and (b) talker characteristics. Results were: (1) listeners were able to rate intelligibility, (2) rankings based on intelligibility ratings of three CD passages per hearing aid were capable of identifying two superior instruments within a group of four hearing aids that were similar in frequency/gain function, (3) listening in a more difficult S/B ratio substantially decreased the sensitivity of the hearing aid rankings for the female talker but had only minor effects on the rankings for the male talkers, and (4) hearing aid intelligibility rankings were found to be different for different talkers. Applications to hearing aid selection are discussed.

Adult↗