Narrowband, and more frequently Wideband are becoming buzzwords in the telecom world. Narrowband and Wideband audio refers to telephone audio sampling, how much of the frequency range is sampled provides us with the differences of narrowband and wideband. Narrowband audio is sampled at 8,000 Hz and Wideband is sampled at 16,000 Hz providing a much wide range of human tonality to pass through.
Narrowband comes in many variations, but the most traditional version of this style of codec is the G.711. G.711 actually refers to two different codecs: G.711 mu-law is used in North America while G.711 a-law is used in Europe. G.711 processes each individual call at 64 kb/s, the same speed as a T0 channel (B Channel on a T1 circuit). It is also the standard codec used in traditional phone lines, known as pulse code modulation (PCM). Being such a ubiquitous codec, the advantage of G.711 is it is incredibly simple and standard to implement. No processing power is needed to convert audio from G.711 into another format in order to call outside the office. One more major advantage of G.711 is the fact that the patents have expired on the technology, making it free to implement in phone calls.
Sampling Frequency: 8 kHz
8 Bits per Sample
Bit rate: 64 kb/s
Algorithmic Delay: 0.125 ms
Waveform Speech Coder
Wideband audio is commonly known as HD voice. Wideband comes in two main variations, known as G.722 and G.722.2. Despite having very similar names, these codecs behave quite differently.
G.722 works by doubling the sampling of audio frequencies from 50 Hz to 7 kHz. G.722 works by increasing the bandwidth required to transmit the call, and is commonly used with ISDN circuits or SIP trunking. With today’s increased network bandwidth, users can more easily take advantage of the increased fidelity.
Sampling Frequency: 16 kHz
Frequency: 50 – 7000 Hz
Bit rate: 64 kb/s