Audible sounds are vibrations that travel through the air and can be detected by the human ear. These sounds are produced by various sources, such as musical instruments, voices, and machines. The frequency of these vibrations determines the pitch of the sound, while the amplitude affects its loudness. The range of audible sounds for humans typically falls between 20 Hz and 20,000 Hz. Sounds below 20 Hz are called infrasound, while those above 20,000 Hz are known as ultrasound. Different animals may have varying ranges of hearing, allowing them to perceive sounds that humans cannot.