Acoustics is the science that deals with the study of sound and its production, transmission and effects. Especially it involves the study of mechanical waves in solids, liquids and gases which includes sound, vibration, ultrasound and infrasound. The main application of acoustics is to make the music or speech sound as good as possible. It is achieved by reducing the sound barriers and increasing the factors that help in proper transmission of sound waves. Initially acoustics was used only in industries which are based on sound like auditorium, theatre but application of acoustics spreads to many fields like medicine, warfare, architectural industries etc.


A scientist or researcher who studies acoustics is called Acoustician and someone working in the field of acoustics technology will be called as Acoustical Engineering.

Acoustic Energy

Acoustic energy can be defined as the disturbance of energy which passes through matter in the form of a wave. In other words, it is the energy concerning the mechanical vibrations from its components is called Acoustic Energy. Any acoustic event has following stages.

Cause  Generating Mechanism  Acoustic wave propagation  Reception Effect

The process in which some other form of energy is converted into sonic energy  producing a sound wave is called transduction process. Sound waves carries energy throughout the propagating medium. Acoustic wave equation is the fundamental equation that describes sound wave propagation. Wave propagation is the key process in any of the acoustic event. Sound propagates in liquids as pressure wave and in solids as a longitudinal or transverse waves.

Acoustic Energy

Sub disciplines of Acoustics

Environmental Noise

Environmental Acoustics is concerned with vibration and noise caused by road ways. Railways, aircraft and general activities that are related to environment. The main goal of these is to reduce vibration and noise that affects environment.

Musical Acoustics

Musical acoustics is concerned with the study of physics of music i.e., how sounds are used to make music. Areas of study includes human voice, musical instruments and music therapy.

Ultra sounds

Ultra sounds are the sounds with a frequency greater than human audible limit. However there is no difference in physical properties when compared to normal sound. Ultrasound is used in many fields. Ultrasonic devices are used in measuring distances and in detecting objects. Ultrasound imaging is used in physics.

Infra sounds

Infrasounds are the sounds with a frequency less than 20 Hz. The study of such sounds is called infra sonics. Applications include detection of petrol formation under the earth and possibility of earthquakes.

Vibration and Dynamics

It is the study of how mechanical systems vibrate and interact with their environment. Applications include Vibration control which helps to protect building from earthquakes and ground vibrations used in railways.

Practise This Question

If lens I with focal length +15 cm and lens II has focal length +30 cm. find out which lens has more power?