An Evaluation of a Spoken Language Interface

Report No. ARL-TR-3477
Authors: Paula P. Henry, Timothy J. Mermagen, and Tomasz R. Letowski
Date/Pages: April 2005; 30 pages
Abstract: Speech recognition software has been proposed for inclusion in the Future Force Warrior system. DynaSpeak is a speech recognition software product developed by SRI International that has been shown to function well in quiet environments. However, the system has not yet been evaluated in noise environments representative of Army operational environments. This report summarizes a study that was conducted to evaluate the performance of the DynaSpeak software in the presence of two types of noise: steady state noise obtained from a tracked vehicle and impulse noise obtained from gunfire. Simultaneous recordings were made from 12 participants wearing two microphones: a Gentex noise-canceling boom microphone and a Temco HG-17 bone conduction microphone. The 12 participants verbalized call signs and commands which were analyzed by the speech recognition software. The results of the present study show that the DynaSpeak software functions well through the boom microphone in moderately high steady state noise (90 decibels A-weighted [dBA]) with error rates for words of 2% to 5%. However, the performance of the system with the same boom microphone in high steady state noise levels (110 dBA) or in moderately high impulse noise levels (90 dBA) does not meet the requirements for military applications. Error rates for words in these conditions ranged from 14% to 40%. If the DynaSpeak software is to be used in environments of impulse noise or high levels of steady state noise, the performance of the system must be enhanced.
Distribution: Approved for public release
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Last Update / Reviewed: April 1, 2005