Engineering and Computer Science Faculty Publications

Approximation and Optimization of an Auditory Model for Realization in VLSI Hardware

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The Auditory Image Model (AIM) is a software tool set developed to closely model the role of the ear in the human hearing process. AIM includes detailed filter equations for the major functional portions of the ear. Currently, AIM is run on a workstation and requires 10 to 100 times real-time to process audio information and produce an auditory image.

An all-digital approximation of the Auditory Image Model (AIM) which is suitable for implementation in very large scale integrated circuits is presented. This report details the mathematical models of AIM and the approximations and optimizations used to simplify the filtering and signal processing accomplished by AIM. It concludes by providing an efficient multi-rate architecture designed for sub-micron VLSI technology to carry out the approximated equations. Finally, test results comparing the approximated system to the original AIM model are discussed.

The details of a new and efficient method for computing an approximate logarithm (base two) on binary integers is also presented. The approximate logarithm algorithm is used to convert sound energy into millibels quickly and with low power. The algorithm, however, is easily extended to compute an approximate logarithm in base ten which broadens the class of problems to which it may be applied.


Dissertation submitted to the Air Force Institute of Technology