Voice frequency

A voice frequency (VF) or voice band is one of the frequencies, within part of the audio range, that is used for the transmission of speech.

In telephony, the usable voice frequency band ranges from approximately 300 Hz to 3400 Hz. It is for this reason that the band of the electromagnetic spectrum between 300 and 3000 Hz is also referred to as "voice frequency" (despite the fact that this part of the electromagnetic spectrum is rarely used to actually convey audio signals). The bandwidth allocated for a single voice-frequency transmission channel is usually 4 kHz, including guard bands, allowing a sample rate of 8 kHz to be used as the basis of the pulse code modulation system used for the digital PSTN.

Fundamental frequency
The voiced speech of a typical adult male will have a fundamental frequency of from 85 to 155 Hz, and that of a typical adult female from 165 to 255 Hz. Thus, the fundamental frequency of most speech falls below the bottom of the "voice frequency" band as defined above. However, enough of the harmonic series will be present for the missing fundamental to create the impression of hearing the fundamental tone.