Frequency Response Unit

The frequency response of a speaker refers to the phenomenon where the sound pressure generated by the speaker varies with frequency when connected to an audio signal with a constant voltage output. This variation in sound pressure and phase with frequency is known as the frequency response. The frequency response range is the span between the lowest effective sound frequency and the highest effective sound frequency, measured in Hertz (Hz).

Bandwidth Expansion

In theory, a frequency response of 20 to 20,000 Hz is sufficient. Sounds below 20 Hz are inaudible, but they can be sensed by other sensory organs, which is the so-called bass strength of a speaker. Therefore, to accurately reproduce various musical instruments and language signals, amplifiers must achieve high fidelity to replay all harmonics of the pitch. Consequently, the amplifier's frequency range should be expanded, with the lower limit extending below 20 Hz and the upper limit raised above 20,000 Hz. This range aligns with the frequency spectrum of sounds that the human ear can hear.

The range of human hearing

The human ear can perceive sound frequencies ranging from 20Hz to 20kHz, and the audio signal in this range must maintain a linear response in the player. The lowest frequency a speaker can produce starts at 20Hz and extends up to the highest frequency of 20kHz; frequencies below 20Hz and above 20kHz are inaudible to the human ear. The operating frequency range of a typical MP3 player's power amplifier is 20Hz to 20kHz.