Scale helps us to handle numbers on a wide scale much more easily. In the following chart, some sounds are expressed both linearly You can click on the demo button to learn the formula. In decibels (dB), can then be obtained using the following formula. Sound pressure level, which is often abbreviated as SPL or L p, The scale uses the hearing threshold of 20 μPa or 20 x 10 -6

Involve some unmanageable numbers, the decibel or dB scale is used. To avoid expressing sound or noise in terms of Pa, which could [Animation illustrates relationship between linear and logarithmic Introduction of the common logarithm to the base 10.Ĭlick on the demo button, you may learn more about the relationship The following table illustrates sound pressure level of the above events expressed in Pa and µPa.Ī simpler way is to use a logarithmic scale for the loudness On the other hand, the sound pressure close to some very noisy events such as launching of the space shuttle can produce a large pressure variation at a short distance of approximately 2000 Pa or 2 x 10 9 µPa. The softest sound a normal human ear can detect has a pressure variation of 20 micro Pascals, abbreviated as µPa, which is 20 x 10 -6 Pa ('20 millionth of a Pascal') and is called the Threshold of Hearing. Human ear can perceive a very wide range of sound pressure. In Pascal, abbreviated as Pa, which is defined as N/m 2(Newton Pressure and pressure variations are expressed Usually has a larger pressure variation and a weak one has smaller

PleaseĬlick on the demo button to hear their sounds and the differenceĪnother property of sound or noise is its loudness. Produced by a whistle, as shown in the following diagrams. The sounds produced by drums have much lower frequencies than those The higher the frequency, the more high-pitched a sound is perceived. Is called the frequency of sound, and is measured in Hertz (Hz) The number of pressure variations per second When sound travels through air, the atmospheric pressure Sound is the quickly varying pressure wave travelling through a There are two important characteristics of sound or noise - frequency

Decibel scales