Infrasonic
An infrasonic waveform has a frequency too low to directly hear. It repeats less than about 20 times a second, known as 20 Hz.
Although you can't hear a waveform this low, you can hear a difference between two sonic waveforms that is itself this low, known as beating. You can also hear modulation this low, such as vibrato.
In the context of synthesis, infrasonic waveforms can be made using LFOs.
Contrast with sonic frequencies, between about 20 Hz and 20 kHz, and ultrasonic frequencies, above about 20 kHz.
Frequency ranges: Infrasonic | Sonic | Ultrasonic
