Analysis of a digital technique for frequency transposition of speech
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Authors
DiGirolamo, Vincent
Subjects
Frequency transposition
Speech
Hearing impaired
Pole shifting
Frequency content
Linear predictive coding
Reflection coefficient
LPC parameters
Speech processing
Speech
Hearing impaired
Pole shifting
Frequency content
Linear predictive coding
Reflection coefficient
LPC parameters
Speech processing
Advisors
Moose, Paul H.
Date of Issue
1985-09
Date
September 1985
Publisher
Language
en_US
Abstract
Frequency transposition is the process of raising or lowering the frequency content (pitch) of an audio signal. The hearing impaired community has the greatest interest in the application of frequency transposition. Though several analog and digital frequency transposing hearing aid systems have been built and tested, this investigates a possible digital processing alternative. Pole shifting, in the z-domain of an autoregressive (all pole) model of speech was proven to be a viable theory for changing frequency content Since linear predictive coding (LPC) techniques are used to code, analyze and synthesize speech, with the resulting LPC coefficients related to the coefficients of an equivalent autoregressive model, a linear relationships between LPC coefficients and frequency transposition is explored. This theoretical relationship is first established using a pure sine wave and then is extended into processing speech. The resulting speech synthesis experiments failed to substantiate the conjectures of this thesis. However, future research avenues are suggested that may lead to a viable approach to transpose speech.
Type
Thesis
Description
Series/Report No
Department
Department of Electrical and Computer Engineering
Organization
Naval Postgraduate School (U.S.)
Identifiers
NPS Report Number
Sponsors
Funding
Format
Citation
Distribution Statement
Approved for public release; distribution is unlimited.
Rights
This publication is a work of the U.S. Government as defined in Title 17, United States Code, Section 101. Copyright protection is not available for this work in the United States.