The Human Perception of Loudness
Aim: The aim of the experiment was to discover the difference between loudness and sound pressure level, gain knowledge of typical sound level values in common environments and to be able to make rough estimations of what sound level measurements could be in different places.
Method: The CEL-440 sound level meter was used to measure sound pressure levels in dbz and loudness levels in dBA. It was decided to base the experiment on learning environments around the university, ranging from areas of study inside and outside. This was done because, as the areas that are considered in the experiement are ones that the group would use in everyday life so it would be interesting to see what loudness and sound pressure levels most people live and sit in during there every day lives.
Loudness is a psychological quality which relies on human interpretation. Loudness is hard to measure as it depends on how the human ear responds to it. Sound Pressure Level is linked to loudness as it is a physical quantity which can be measured. Sound Pressure Level can be measured, when loudness cannot. Sound pressure level ranges from the smallest detectable sound which is measured in pa (pascals). Sound is heard, by air follicles vibrating on the ear. The highest sound is atmospheric pressure around 1,000,000pa that can not physically be heard. If it was any louder then there would not be any atmospheric pressure left so everything would be destroyed. Threshold of human aural perception is the pressure of the air molecules colliding with the ear drum which is close to the threshold of perception. Young people with sensitive hearing are able to hear as little as 20pa, but most people will not be able to hear this measurement. The just noticeable difference depends on factors such as overall levels and frequencies. However, it is conveniently remembered as 1dB, one decibel. When something is measured in decibels it is refering to ratio (10log power...
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