Voice frequency

voice frequency (VF): Pertaining to those frequencies within that part of the audio range that is used for the transmission of speech.

Note 1: In telephony, the usable voice frequency band ranges from approximately 300 Hz to 3400 Hz.

Note 2: In telephony, the bandwidth allocated for a single voice-frequency transmission channel is usually 4 kHz, including guard bands. Synonym voice band.

Source: from Federal Standard 1037C and from MIL-STD-188