DATE 07 MARCH 2008
Noise, commonly described as unwanted sound, is of major concern in the environment ,either domestically or industrial. This is because noise can damage people’s hearing mechanisms or can interfere with one’s enjoyment peace and quiet of his home. Noise should therefore be controlled. Laws have been enacted in relation to control of noise in order to protect the public and people at work.
Noise control is based on the principle that for noise to be perceived there should be a source of acoustic energy, the transmission path of that energy and the receiver. Action taken on any of the three properties should have an effect on the amount of sound reaching the ear.
These could either be engineering controls, administrative controls , or use of personal protective equipment.
In view of the above facts regarding noise , theories have been known in relation to noise attenuation. Some proven and put into practice. In this exercise we attempt to determine what attenuation can be achieved by increasing distance from source and also by enclosing the source of sound in an acoustic box .
To explore the performance of enclosures , and attenuation through enclosure and distance from source.
a ) An sound level meter with integrated frequency analyser was used. This is a battery operated portable instrument with a linear frequency response and when the weighted switch is set to linear , it registers the total sound level in dB. It has an octave band analyzer which will measure the levels at the nominal mid frequencies of 31.5 ; 63 ; 125; 250; 1000; 4000 ; 8000 Hz. This is to give it a similar frequency response to that of an ear.
b) hoover to act as a point source of sound
c) acoustic box
d) tape measure