Complex sentence: The range of the human voice extends from 80 Hz to 14 kHz but traditional, voiceband or narrowband telephone calls limit audio frequencies to the range of 300 Hz to 3.4 kHz.
Split into simpler sentences: The range of the human voice extends from 80 Hz to 14 kHz. Traditional, or narrowband telephone calls, limit audio frequencies to the range of 300 Hz to 3.4 kHz.