Masking of Tone Bursts by Modulated Noise in Normal, Noise-Masked Normal, and Hearing-Impaired Listeners Threshold of 4.6-ms tone bursts was measured in quiet and in the presence of a 100% sinusoidally amplitude-modulated speech-shaped noise. For the modulated-noise conditions, the onset of the tone burst coincided either with the maximum or the minimum modulator amplitude. The difference in these two masked thresholds provided an indication ... Research Article
Research Article  |   March 01, 1990
Masking of Tone Bursts by Modulated Noise in Normal, Noise-Masked Normal, and Hearing-Impaired Listeners
 
Author Affiliations & Notes
  • Larry E. Humes
    Indiana University
  • Requests for reprints should be sent to Larry E. Humes, Department of Speech and Hearing Sciences, Indiana University, Bloomington, IN 47405.
Article Information
Research Articles
Research Article   |   March 01, 1990
Masking of Tone Bursts by Modulated Noise in Normal, Noise-Masked Normal, and Hearing-Impaired Listeners
Journal of Speech, Language, and Hearing Research, March 1990, Vol. 33, 3-8. doi:10.1044/jshr.3301.03
History: Received March 13, 1989 , Accepted June 23, 1989
 
Journal of Speech, Language, and Hearing Research, March 1990, Vol. 33, 3-8. doi:10.1044/jshr.3301.03
History: Received March 13, 1989; Accepted June 23, 1989

Threshold of 4.6-ms tone bursts was measured in quiet and in the presence of a 100% sinusoidally amplitude-modulated speech-shaped noise. For the modulated-noise conditions, the onset of the tone burst coincided either with the maximum or the minimum modulator amplitude. The difference in these two masked thresholds provided an indication of the psychoacoustic modulation depth, or the modulation depth preserved within the auditory system. Modulation frequencies spanning the modulation spectrum of speech (2.5 to 20 Hz) were examined. Tone bursts were 500, 1400, and 4000 Hz. Subjects included normal listeners, normal listeners with a hearing loss simulated by high-pass noise, and hearing-impaired listeners having high-frequency sensorineural hearing loss. Normal listeners revealed a psychoacoustic modulation depth of 30–40 dB for the lowest modulation frequencies which decreased to about 15 dB at 20 Hz. The psychoacoustic modulation depth was decreased in the normal listeners with simulated hearing loss and in the hearing-impaired listeners. There was general agreement in the data, however, for the latter two groups of listeners suggesting that the normal listeners with hearing loss simulated by an additional masking noise provided a good representation of the performance of hearing-impaired listeners on this task.

ACKNOWLEDGMENT
This research was supported, in part, by grants from NIH, the Veterans Administration, and the Air Force Office of Scientific Research. The expert assistance of Dr. Christopher Ahlstrom in all phases of data collection and reduction is gratefully acknowledged.
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