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Room Acoustics: The Purpose Of Room Acoustics

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Room acoustics
"A person with normal hearing will commonly experience same difficulty in understanding speech in a large auditorium, even it has been well designed because the unamplified voice of the average person is generally inadequate to 'fill' the auditorium. Consequently, a person with even a minor hearing impairment may have considerable difficulty in listening to speech in large rooms. As a result, complaints concerning the poor acoustics of an auditorium may come from a person with slightly impaired hearing of which they are not even aware." (Vem O. Knudsen, 1978)
Auditorium is an enclosed place; for speech, music, drama etc. So enclosed space intended for this purpose should be designed to achieve the following main objectives.
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Acoustics is a science of sound. Building acoustics or auditorium acoustics comprises both, the control of noise within auditorium and the design of auditorium for good hearing conditions. In a auditorium performer is the source and audience are receivers. When the vibrating body swings in a forward direction it compresses a layer of air around it increasing its density and temperature. Air molecules in this layer now being at higher pressure than the next undisturbed layer transmits their motion to the adjacent layer. That layer further transmits its motion to the another layer and so on. Mean while the body takes a backswing with the result that the air around it now gets rarefied causing a decrease in its density and temperature. This rarefaction of air follows its compression at the same speed although the air does not change its average position. Thus with the continuous outward and inward swings of the body that follows a definite pattern of compression and rarefaction of layers and this effect progresses outward from the body in all directions and this is known as wave motion of sound. So sound has a direction quality as well as a spherical wave front. So for propagation of sound wave, medium is…show more content…
In acoustical problems the sound intensity is expressed by another convenient unit called decibel (dB) which 1/10 of bel unit.
Intensity of sound is a physical measurement of a sound that relates to how loud sound is perceived. The term used to express human perception of intensity is loudness, a word which has a special meaning in architectural acoustics. Pitch is the term used to indicate human response to the frequency of sound. Loudness is a composite judgement which depends on the frequency of sound as well as its intensity.
Sound pressure is the air pressure above all normal atmospheric pressure caused by sound pressure pulses. Pressure pulses or sound waves spread out in all directions from sound source, each forming a continuously expanding spherical wave front. The area of surface of a sphere is directly proportional to the surface of its radius. For every doubling of the distance from the source the sound power of source is spread over a surface that is increased by four times, so that the intensity of sound decreases by a factor of four. So as you go away from the source loudness of sound
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