The Room Acoustic Parameters are calculated from the energy impulse response, as we have seen it just above, and they quantify various sound attributes in the room. Programs like ODEON work with an additional two octave bands (63 Hz and 8000 Hz), resulting in a total of 8 absorption coefficients. Therefore, a material is described by a series of 6 absorption coefficients. In Room Acoustics, we are mainly interested in frequencies from 125 Hz to 4000 Hz, divided in 6 full octave bands, centred at 125, 250, 500, 1000, 20 Hz. An open window is the obvious example of an ideally soft surface.Įach material in room acoustics is associated with an absorption coefficient that varies throughout the frequency range. The absorption coefficient is simply the non-reflected sound energy (absorbed or transmitted) divided by the sound energy that hits the wall.įor an ideally hard wall, no energy would be absorbed, so the absorption coefficient would be 0, while for an ideally soft wall, all energy would be absorbed, so the absorption coefficient would be 1.

This ability comes from the actual material that the wall is built from, and is quantified by the absorption coefficient, a real number from 0 to 1.

PA line arrays are typically too large and too close to the listeners, so it is not feasible to approximate it as a point source unless very far away.Īs mentioned before, walls have the ability to absorb part of the sound energy that hits them. Musical instruments are a little more complicated because they can radiate sound from different parts (the holes, body, strings etc.), but again they are treated as point sources for most practical room acoustic applications.A loudspeaker can be considered a point source too if we are listening from at least 1m away.A person speaking, where sound comes mostly from the mouth, can be considered a point source if we stand a few centimetres away.Point sources and their directivities can be used to represent the majority of sources in real life, but only when the listener is away from the source at least at a distance comparable to the source: stronger in front of the source) a directivity pattern is needed to describe it. A point source that radiates sound equally to all directions is called omnidirectional. The simplest type of source is the point source, where sound is assumed to be generated at an ideal point in space.

Room acoustic analysis software