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Biomedical subjects

E D Schubert

Publications and source records attributed to E D Schubert.

7 recordsLinked to original sources
PubMed1991

Comodulation masking release and the masking-level difference.

An experiment was performed to determine if the mechanism that mediates comodulation masking release (CMR) is associated with that used to improve detection by the masking-level difference (MLD). The experiment consisted of first improving detectability of a masked diotic tone burst by adding a synchronous noise band at another frequency region (CMR), and then measuring an MLD in the usual manner, by inverting the tone-burst signal to one ear. Results indicate that a substantial MLD can be measured for a signal whose detectability has already been improved by CMR. However, that MLD (9 dB) is smaller than that measured in random noise (14 dB). Put another way, a small CMR (4 dB) can be produced even when the detectability of a stimulus has already been improved due to the MLD. These data are in general agreement with those of Hall et al. [J. Acoust. Soc. Am. 83, 1839-1845 (1988)] and Schooneveldt and Moore [J. Acoust. Soc. Am. 85, 262-272 (1989)].

Adolescent↗
PubMed1991

Middle-ear muscle activity (MEMA) and its association with motor activity in the extremities and head in sleep.

Middle-ear muscle activity (MEMA) in sleep was simultaneously recorded from both ears using extratympanic manometry. Head movement, speech movements, ankle flexion and wrist movement were monitored by electromyographic recording using surface electrodes at the back of the neck, second laryngeal notch, anterior tibialis and forearm muscle. Motor events recorded from these electrode placements were examined for correlation with MEMA to test the hypothesis that the middle-ear muscles are activated in conjunction with other motor activities, aside from eye movements, by a central motor command system. Phi coefficients were calculated for each subject; all were positive, thus indicating an association between MEMA and other noneye movement motor events. These results suggest that there is a central phasic motor system responsible for MEMA and associated phasic motor activity in sleep.

Adult↗
PubMed1990

Speech recognition in analog multichannel cochlear prostheses: initial experiments in controlling classifications.

Computer-synthesized vowels were used to examine methods for controlling and measuring the perceptions elicited during electrical stimulation of the human cochlea. In the first experiment, we measured the importance of the second formant (F2) in the identification of vowels, matched for duration, in a single subject with a multichannel cochlear implant. The subject never confused vowels having a "low" frequency F2 with those having a "high" frequency F2. In the second experiment, identification functions were generated for a series of vowels varying only in F2. When the pattern of F2 stimulation at the basilar membrane was manipulated, vowel identification functions were altered. For the categorization of vowels, the data indicate that the relative cochlear position of F2 stimulation was more important than fine-grain temporal waveform cues. The data are supportive of cochlear implant coding strategies that make use of cochlear place information. In the later experiments, we manipulated filter passbands and channel gains to explore their effect on these classifications. These preliminary studies indicate that it is possible to "fine-tune" such classifications.

Aged↗
PubMed1979

Hearing performance inventory.

The Hearing Performance Inventory (HPI) was developed to assess hearing performance in problem areas experienced in everyday listening. It consists of six sections: (1) Understanding Speech, (2) Intensity, (3) Response to Auditory Failure, (4) Social, (5) Personal, and (6) Occupational. A self-report response style is used. Sentences were written to describe a number of listening situations covering a variety of talker characteristics and communication processes. The development, current status, and clinical implications of the HPI are presented.

Attitude to Health↗
PubMed1977

Development of the California Consonant Test.

A 100-item, multiple-choice test for consonant identification labeled the California Consonant Test (CCT) has been developed expressly for use with hearing-impaired patients. A computer-assisted analysis was obtained for the test responses of 550 patients with sensorineural hearing loss. The test seems highly sensitive to configurations of high-tone loss, but the correlation with degree of loss, especially in the instance of flat configurations, is somewhat low (-0.40). Test-retest correlation is 0.96. A correlation of 0.35 with a W-22 list indicates that the two tests are measuring different aspects of speech reception. In addition to its usefulness in identifying consonant confusions for rehabilitation purposes, the CCT may prove helpful in ranking hearing aids. For the latter purpose, two 50-item subforms, designed for equivalence, have been under observation for possible use when time is a critical factor. Repetitions of the 100-item list offer greater stability, however.

Auditory Perception↗
PubMed1976

Binaural masking effects in bone-conducted noise.

When pure tones are masked by bone-conducted noise presented at the midline of the forehead, it is possible that binaural unmasking may occur due to the interaural phase relations of the noise. To study this possibility, the amount of masking produced in bone-conducted noise, in correlated air-conducted noise, and in monaural noise was determined using narrow bands of noise centered at 240, 500, 910, and 1900 Hz as markers and a block up-down two-interval forced choice procedure. The subjects were four women under 30 years of age with 10 dB HTL or better (ANSI, 1969) for the frequencies tested. The amount of unmasking (the masking-level difference) was determined by subtracting the masking levels obtained under each noise condition at each frequency from those obtained in the comparable monaural noise-monaural signal condition. Levels of binaural unmasking obtained in correlated air-conducted noise agreed with those in previously reported experiments. Comparable binaural unmasking effects were demonstrated for midline presentation of bone-conducted noise. Some clinical implications of the findings are discussed.

Acoustic Stimulation↗