The ability of people to produce and hear sound is a very important part of everyday lives. Biophysics tells you what the properties of waves are, and it tells you that sound is a longitudinal pressure wave (in air) that is produced by mechanical vibrations. Biophysics also tells you how people can produce pressure waves for communicating with others and for singing. In addition, biophysics allows you to understand how people receive and analyze the pressure waves absorbed by the ear.
The body has five senses, hearing being one of them. Your ear allows you to hear the pressure waves produced by others and any noise in the frequency range of 20 hertz to 20,000 hertz. Even though your ear can hear over such a large range of frequency, the human voice uses only the frequency range from about 100 hertz to 3,000 hertz.
The pressures waves in air can be split into three categories, based on human hearing, as follows:
Infrasound: Pressure waves with frequencies below 20 hertz. Some animals, such as whales, produce sound in this frequency range.
Sound or acoustic: Pressure waves in the frequency range of 20 hertz to 20,000 hertz. This is the range of frequencies that the human ear can detect.
Ultrasound: Pressure waves with a frequency greater than 20,000 hertz. Some animals, such as bat,s use this type to hear; it’s also used for ultrasound imaging.
