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Dissertation
The role of parametric demodulation and the quadratic property in human amplitude-modulated ultrasonic hearing
Doctor of Philosophy (Ph.D.), Drexel University
1993
DOI:
https://doi.org/10.17918/00009568
Abstract
This dissertation studies the roles of parametric demodulation model and two physical demodulation models, the rectifying amplitude demodulation model and the coherent amplitude demodulation model in human amplitude-modulated (AM) ultrasonic hearing. The parametric demodulation of focused AM ultrasound with Gaussian distribution and diffraction in dissipative media was modified and computed in order to study parametric demodulations of a set of monotone focused AM ultrasound in human auditory system. This set of monotone AM ultrasonic modes (standard AM mode, carrier-suppressed AM mode and square-root AM mode) was selected as the stimuli for human tests, in order to provide distinct and simple frequency patterns of demodulations in the three physical demodulation models. The predicted frequency patterns of parametric demodulations of these AM ultrasonic modes were obtained in parametric demodulation measurements. These frequency patterns were partially observed in human auditory sensation in response to the stimulation of the same AM ultrasonic modes. The analysis of these observed frequency patterns indicates the existence of quadratic property in human AM ultrasonic hearing. Parametric demodulation is determined by this analysis to have a joint influence in conjunction with the quadratic rule on human AM ultrasonic hearing, while the rectifying amplitude demodulation and the coherent amplitude demodulation are determined to be irrelevant to ultrasonic hearing. The square-root pre-conditioning in verbal-modulated ultrasonic stimulation in human subject tests were proved to be effective in improving the quality of verbal recognition in verbal-modulated ultrasonic hearing.
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Details
- Title
- The role of parametric demodulation and the quadratic property in human amplitude-modulated ultrasonic hearing
- Creators
- Shengke Zeng
- Contributors
- Richard B. Beard (Advisor) - Drexel University, Drexel University (1970-)
- Awarding Institution
- Drexel University
- Degree Awarded
- Doctor of Philosophy (Ph.D.)
- Publisher
- Drexel University; Philadelphia, Pennsylvania
- Number of pages
- xvi, 180 pages
- Resource Type
- Dissertation
- Language
- English
- Academic Unit
- Drexel University
- Other Identifier
- 991021888821704721