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what are the characteristics of sound?

Characteristics of sound : A sound is identified and interpreted by three characteristics -loudness, pitch and quality. All the three are related to objectively defined quantities- loudness is related to intensity, pitch is related to frequency and quality is related to waveform of the sound wave.

Intensity of sound at any point in space is defined as the amount of vibrational energy passing per unit time per unit area around that point in a direction normal to the area. Its SI units is W m^-2. It is a physical quantity.

Loudness is the sensation produced in the ear which enables to distinguish between a loud and a faint sound. It depends upon intensity of sound and sensitiveness of the ear. It is measured in terms of bel. It is not a physical quantity. Intensity or loudness depends upon the following factors.

Intensity of sound is directly proportional to

• square of the amplituee (A2) of the vibration of the vibrating body
• surface area (a) of the medium
• density (?) of the medium
• square of the frequency (v2) of the source
• motion of the medium and
• inversely propotional to the square of the distance of the listener from the source of sound.

Pitch of a sound is that subjective property which distinguishes a sharp sound from a dull sound. Pitch depends on an objective quantity frequency of the source (v).

Quality or timbre or tone colour is that subjective characteristic of sound which enables us to distinguish between two sounds of the same loudness and the same pitch but emitted by two different sources. The quality of sound depends on the waveform which is determined by the number of overtones present and their respective intensities.

Sound of a single frequency is known as 'tone' while sound made up of many frequencies is known as a 'note'.