Acoustics, the branch of physics that deals with the production, transmission, properties, and effects of sound waves. It includes the following areas of study:

Architectural Acoustics is concerned with the behavior of sound waves in enclosed areas such as auditoriums, theaters, recording studios, and churches. Its goal is to achieve the proper conditions for hearing or recording speech and music in such areas.

Musical Acoustics deals with musical sounds and with the theory and design of musical instruments.

Physiological Acoustics deals with hearing and speech.

Underwater Acoustics is concerned with the behavior of sound waves in water, especially in seawater.

Electroacoustics deals with methods and devices for converting sound energy into electrical energy or vice versa. It is concerned with the design of such devices as compact disc players, tape recorders, microphones, and loudspeakers.

Noise Control is concerned with the measurement and reduction of unwanted sound.

Ultrasonics is the science of sound waves having frequencies that are beyond the upper limit of normal human hearing. This upper frequency limit is generally taken to be 20,000 hertz (cycles per second).