Steven Voepel

Publication Date

1992

Document Type

Dissertation/Thesis

First Advisor

Kuo, Sen M. (Sen-Maw)

Degree Name

M.S. (Master of Science)

Legacy Department

Department of Electrical Engineering

LCSH

Hearing aids

Abstract

This thesis presents frequency domain techniques based upon relatively new transforms, called lapped transforms, for utilization in a digital hearing aid. The lapped transform promotes this new frequency domain digital hearing aid by possessing the ability to eliminate the blocking effects inherent in traditional frequency domain filtering, where block transforms such as the Discrete Fourier Transform (DFT) and Discrete Cosine Transform (DCT) are commonly employed. Incorporated into the frequency domain digital hearing aid are the functions of frequency shaping, acoustic feedback cancellation, and periodic noise reduction. The benefit of using frequency domain techniques allows all the necessary information to properly adjust the digital hearing aid to be known using a single transform. Therefore, these three functions can easily be integrated into a complete and efficient system. Computer simulations demonstrate and support the ease of hearing enhancement these three functions can perform for the dynamically changing environment a hearing impaired person encounters. The frequency shaping mechanism is based upon the use of a dynamic sound level control to determine proper gain adjustment. Acoustic feedback cancellation will use a frequency domain adaptive filter via the LMS update algorithm for computational simplicity, yet provide the necessary performance needed. Periodic noise reduction involves conditional testing using a power estimation technique based upon the strength and longevity of the noise source.

Comments

Includes bibliographical references (pages [115]-[116])

Extent

xi, [116] pages

Language

eng

Publisher

Northern Illinois University

Rights Statement

In Copyright

Rights Statement 2

NIU theses are protected by copyright. They may be viewed from Huskie Commons for any purpose, but reproduction or distribution in any format is prohibited without the written permission of the authors.

Media Type

Text

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