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Biomedical subjects

G A Studebaker

Publications and source records attributed to G A Studebaker.

At least 37 records · Page 2Linked to original sources
PubMed1985

A "rationalized" arcsine transform.

Arcsine or angular transformations have been used for many years to transform proportions to make them more suitable for statistical analysis. A problem with such transformations is that the arcsines do not bear any obvious relationship to the original proportions. For this reason, results expressed in arcsine units are difficult to interpret. In this paper a simple linear transformation of the arcsine transform is suggested. This transformation produces values that are numerically close to the original percentage values over most of the percentage range while retaining all of the desirable statistical properties of the arcsine transform.

Mathematics↗
PubMed1984

An evaluation of some assumptions underlying the articulation index.

The purposes of this investigation were to derive measurement and calculation procedures for the articulation index (AI) that were as precise and accurate as possible, and to evaluate the significance of the differences in assumptions made by early investigators. A nonsense syllable test specifically designed for this application was recorded. The implications of various assumptions utilized in different approaches to predicting speech sound identification were tested using 13 different conditions which differed with respect to filtering, level of interfering noise, or level of the speech signal. The listeners were three normal hearing individuals. A set of preferred assumptions was chosen based on a post hoc evaluation of the data. Predictions of speech sound identification were good, both for the average listener and for individual listeners.

Humans↗
PubMed1982

Paired comparison judgments of relative intelligibility in noise.

Normal hearing and hearing impaired subjects listened alternately to continuous discourse processed by pairs of binaural hearing aids. In each case, they were asked to judge which pair of aids reproduced speech more intelligibly. Twenty-three pairs of aids competed in three elimination tournaments and one round-robin tournament. Speech discrimination tests obtained via each aid served as the criterion measure of the success of the judgments. The results were that the paired comparison procedure produced more reliable rankings than discrimination scores particularly when the difference between aids was small. Concerning validity, the normal hearing subjects identified the aids producing the best discrimination scores very well. Also, they applied confidence ratings to their judgements that were well related to the size of the performance difference between the aids. The hearing impaired subjects also performed well generally but on occasion individuals in this group chose aids that were clearly not best for them or the group.

Adult↗
PubMed1978

Absolute and relative reliability of several response parameters used in vestibular assessment.

This experiment investigated the reliability of five indices used to express the magnitude of induced vestibular nystagmus. The investigation was undertaken because information concerning the reliability of the various response parameters when caloric testing is repeated on the same subject is limited. Electronystagmographic assessments of the nystagmus response to the Fitzgerald-Hallpike test were obtained from 16 subjects on three occasions with equal intervals of time between occasions. The data were statistically treated with an analysis of variance technique that allows the generation of correlation coefficients. The findings showed that speed of the slow phase, total beats, culmination frequency, and total amplitude reliably express the magnitude of induced nystagmus on repeated tests. Duration of the induced reaction was not as reliable as the other indices on repeated testing. In addition, difference scores were more repeatable than absolute scores and the caution that must be maintained when using correlation coefficient analyses to estimate reliability is highlighted.

Adolescent↗
PubMedDate not supplied

Directivity of the human vocal source in the horizontal plane.

The directional characteristics of a male and a female voice in the horizontal plane were measured in an anechoic room. Results were compared with the only two other studies known to have been done using human subjects. The results of the three studies agree very well. The directional characteristics of two loudspeakers were also measured. One loudspeaker, about the size of the human head, did a fairly good job of emulating the directional characteristics of the human vocal source. Another large loudspeaker did a very poor job. The directional characteristics of a manikin designed and evaluated by Olson (1972. J. Audio. Eng. Soc. 20, 446-451) agreed well with the averaged results from the three studies of human talkers.

Acoustics↗
PubMedDate not supplied

Earmold modification effect measured by coupler, threshold and probe techniques.

The validity of probe tube microphone measurements in providing data indicative of the magnitude of the change in subjects' threshold resulting from changes in earmold configuration was investigated. The relationship between these measures in the real ear canal and the changes observed in 2-cm3 and Zwislocki couplers under similar circumstances or earmold modification was also measured. Standard, vented and 'open' earmold conditions were utilized. Threshold and probe-tube measurements were made. Statistical evaluation revealed that these two techniques did not produce significantly different results except at 125--165 Hz, where noise masking may have been a factor influencing the threshold data. Neither coupler as used gave an accurate quantitative estimate of the in-use effects of vented earmolds or the open earmold configuration, but the Zwislocki coupler gave a better approximation than the 2-cm3 coupler.

Acoustic Stimulation↗
PubMedDate not supplied

Hearing-aid-processed signals: a new approach.

A new protocol for obtaining and utilizing hearing-aid-processed signals in hearing aid research or hearing aid selection is described. Data are presented which illustrate the extent to which this procedure may be expected to result in a signal spectrum at the subject's eardrum which is the same as the spectrum the subject would have received if the hearing aid itself had been placed on his ear (a directly-aided situation). An earlier investigation by the authors indicated that the traditional protocol for the production and utilization of hearing-aid-processed signals results in substantial discrepancies between these two spectra. The data presented were obtained using the KEMAR as the subject with a Zwislocki coupler as the KEMAR's ear canal/eardrum. The discrepancy between directly-aided and hearing-aid-processed spectra was typically +/- 2 dB for ear-level hearing aids fitted using standard, vented, or open earmolds (in open earmold fittings only the amplified component of the directly-aided spectrum is reproduced).

Acoustic Stimulation↗
PubMedDate not supplied

Prediction and statistical evaluation of speech recognition test scores.

A speech test evaluation and presentation system is described. The test presentation subsystem has the flexibility and speed of live-voice testing while using recorded test materials. The speech test evaluation subsystem compares an individual subject's test performance on a monosyllabic word test with that of an average person with the same hearing loss. The elements needed to make such evaluations are discussed. Also, a trial of the procedure is described. The primary purpose of the trial was to obtain data that would provide a basis for statistical probability statements about individual monosyllabic word test results obtained in clinical settings. Data were collected from three audiology clinics in three different types of settings. Except for a few cases with highly asymmetric speech scores, all nonconductive hearing losses were included. Subject ages ranged from 8 to 92 years. Importance-weighted average pure-tone hearing losses ranged from 0.4 to 97.6 dB HL. Fifty-word recognition scores and audiograms for 2609 ears were included in the main analysis. Twenty-five-word recognition scores and audiograms for another 932 ears from one clinic were used in a subsidiary analysis. Results indicated that distributions of absolute speech recognition scores in hearing-impaired samples are highly skewed. However, after transformation of the scores into rationalized arcsine units (rau), the differences between individual subject scores and scores predicted from the audiogram were reasonably well described by the normal distribution. The standard deviation of this distribution of differences, for the data combined across the three audiology clinics, was approximately 13 rau.

Adolescent↗