In electronics, voiceband means the typical human hearing frequency range that's from 20 Hz to 20 kHz. In telephony, it means the frequency range normally transmitted by a telephone line, generally about 200–3600 Hz. Frequency-division multiplexing in telephony normally uses 4 kHz carrier spacing. The rate at which the amplitude of a signal drops off near the upper and lower limits can vary with the design of the band-pass filters. The question of frequency spacing was addressed at an int… (More on Voiceband)