Narrowband (LPC-10) Vocoder Performance under Combined Effects of Random Bit Errors and Jet Aircraft Cabin Noise.
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.
Document Details
- Document Type
- Technical Report
- Publication Date
- Dec 01, 1983
- Accession Number
- ADA141333
Entities
People
- C. P. Smith
Organizations
- Rome Laboratory