Examples of points sources could include valves, small pumps and motors.Ĭalculate the sound attenuation using either metric or imperial units of distance (i.e. To determine the sound attenuation over a distance using the inverse square law, an idealisation needs to be made in which there are no reflective surfaces or barriers between the source and the location at which the sound level is being determined.Īccording to the inverse square law, it can be shown that for each doubling of distance from a point source, the sound pressure level decreases by approximately 6 dB. The problems below are provided as additional problems to the original set of 32 Sound and Music problems.Just like problems in the original set, these problems consist of a problem, an answer (revealed by clicking a link), an audio guided solution, and links to an Overview page of formulas and to The Physics Classroom Tutorial pages. In terms of the propagation and attenuation of sound, the inverse square law is a principle in physics whereby a point source emits a sound wave uniformly in all directions (essentially spherically), where the intensity of the sound wave energy at any given point away from the source is diminished as a function of the total surface area of the sphere coincident with that point. Thus, the equation for intensity is: I I 0 10 / 10. In order to determine an estimate of a sound pressure level at a distance the Inverse Square Law can be used. The human ear is capable of hearing very quiet (low intensity) sounds and extremely loud (high intensity) sounds. We can solve for intensity by multiplying both sides by I 0 which cancels it from the right side.