Formant

Many instruments based on vibrating tubes – including our own vocal tract – have certain frequencies that they like to vibrate or “resonate” at. When you send a sound down these tubes, they will accentuate the frequency of that sound (or some of its harmonics) to match these resonate frequencies. Each of these resonant frequencies is known as a formant of that instrument. A common way of synthesizing vocal-like sounds is to pass an oscillator through a filter or equalizer that has several formant peaks, spaced apart in ways that mimic certain vowels.