Speech Intelligibility Demo

• FM — Software simulation of analog frequency modulation (FM) land-mobile radio (full quieting signal, no interference).

• P25-HR — Association of Public Safety Communications Officials International (APCO) Project 25 half-rate codec (AMBE+2,™ version 1.6).

• P25-FR — APCO Project 25 full-rate codec (AMBE+2,™ version 1.6).

• AMR — Adaptive Multi-Rate codec. From http://www.3gpp.org/DynaReport/26104.htm. ANSI-C code for the floating-point Adaptive Multi-Rate (AMR) speech codec, ETSI/3GPP TS 26.104, Rev. 10.0.0, Apr. 2011.

• AMR-WB — Adaptive Multi-Rate Wideband codec. From http://www.3gpp.org/DynaReport/26204.htm. Speech codec speech processing functions; Adaptive Multi-Rate - Wideband (AMR-WB) speech codec; ANSI-C code, European Telecommunications Standards Institute (ETSI)/3rd Generation Partnership Project (3GPP) TS 26.204, Rev. 10.0.0, Apr. 2011.

• EVS — 3GPP Enhanced Voice Services Codec. From http://www.3gpp.org/DynaReport/26442.htm, Codec for Enhanced Voice Services (EVS); ANSI-C code (fixed-point) 26442-c00-ANSI-C_source_code.zip, (Version 12.0.0) Sept. 2014.

• Opus — Internet Engineering Task Force (IETF) Opus Interactive Audio Codec. From http://www.opus-codec.org, libopus 1.1, Oct. 2014.

Bit Rate
Raw data rate required between encoder and decoder in bits per second. Does not include any forward error correction. No bit errors or packet loss.

Audio Bandwidth

• Narrowband — Supported audio bandwidth has a nominal upper limit between 3 and 4 kHz.

• Wideband — Supported audio bandwidth has a nominal upper limit between 7 and 8 kHz.

• Fullband — Supported audio bandwidth has a nominal upper limit near 20 kHz.

Noise

• Club — Speech combined with recorded nightclub noise at 0 dB signal-to-noise ratio (SNR).

• Siren — Speech combined with recorded fire truck siren at 0 dB SNR.

• Quiet — No extra noise added to speech.

• All — Contains club, siren, and quiet versions, in that order.

Each audio sample in this demonstration includes this speech in this order:

• Female speaker — “Please select the word pin.”

• Male speaker — “Please select the word hark.”

• Female speaker — “Please select the word wig.”

• Male speaker — “Please select the word tip.”

Disclaimer
Certain commercial products, organizations, and companies are identified in this audio demonstration material to specify adequately the technical aspects of the available audio files. In no case does such identification imply recommendation or endorsement by PSCR, National Institute of Standards and Technology Communication Technology Laboratory (NIST CTL), or National Telecommunications and Information Administration Institute for Telecommunication Sciences (NTIA ITS), nor does it imply that the products, organizations, or companies identified are necessarily the best available for the particular application or use.

Listen