Narrowband audio refers to audio signals sampled at 8 kHz, covering the frequency range of approximately 300-3400 Hz. This is the traditional telephone audio quality, also known as toll-quality audio.
Narrowband vs wideband in WebRTC
- Narrowband (8 kHz): Used by G.711 and the PSTN. Adequate for understanding speech but sounds "tinny" and flat
- Wideband (16 kHz): Extends to ~7 kHz, significantly improved voice clarity. Opus supports this and higher
- Super-wideband (32 kHz): Extends to ~16 kHz, near-natural voice quality
- Fullband (48 kHz): Full audio spectrum. Opus at 48 kHz is WebRTC's default
WebRTC's use of Opus at fullband sampling rates means WebRTC-to-WebRTC calls sound dramatically better than traditional phone calls. Audio quality degrades to narrowband only when bridging to PSTN systems that require G.711.
