This frequency range depends on the human hearing characteristics and is strongly subject to the human aging process in the upper frequency range. The audible upper frequency range can drop to 10 kHz and below with age.
The total audio frequency range is divided into the low frequency range, the speech range and the high frequency range. Below the low-frequency range, there is infrasound with subsonic tones, and above the high-frequency range, there is ultrasound, whose frequencies are also imperceptible by humans.
Audio signals include speech, music and noises.