Accession Number : ADA141333

Title :   Narrowband (LPC-10) Vocoder Performance under Combined Effects of Random Bit Errors and Jet Aircraft Cabin Noise.

Descriptive Note : In-house rept. Jun 82-Sep 83,


Personal Author(s) : Smith,C P

PDF Url : ADA141333

Report Date : Dec 1983

Pagination or Media Count : 12

Abstract : Speech intelligibility and voice quality tests were conducted to evaluate the performance of the DOD standard LPC-10 narrowband vocoder algorithm under degradation caused by the combined effects of random bit errors in the data path and background noise accompanying the input speech, as occurs in the acoustic environment in the cabins of an E4B aircraft during operational flight. Vocoder intelligbility scores and voice quality scores indicated that the in-flight acoustic noise environments of the E4B Briefing Room, Battlestaff Compartment, and NCA Compartment were alike in their effects on overall vocoder performance. Composite performance data pooled for the three compartments indicated that vocoder intelligibility averaged 80.2 (fair) with no bit errors, and fell 4-1/2 points with each percent of bit errors incurred in the data path. Thus, the average intelligibility fell to 77.9 (poor) at 1/2 percent error rate, to 73.4 (very poor) at 1-1/2 percent error rate, and to 68.9 (unacceptable) at 2-1/2 percent error rate.

Descriptors :   *Intelligibility, *Speech recognition, *Jet aircraft noise, Data transmission systems, Vocoders, Background noise, Scoring, Aircraft cabins, Speech articulation, Noise(Sound), Electronic aircraft, Performance(Engineering), Algorithms, Acoustics, Environments, Compartments, Paths, Errors, Narrowband, Inflight, Flight, Speech, Degradation, Rates, Input

Subject Categories : Electrical and Electronic Equipment
      Voice Communications

Distribution Statement : APPROVED FOR PUBLIC RELEASE