The Impulse Response

A handclap in the space will produce a series of reflections at a listener position. Each reflection is a modified facsimile of the original event. This series can be broken down into several distinct sound fields. 

The handclap is a crude room impulse response test. The impulse response is displayed here as an echogram. It is a simplified graphical representation of the log squared impulse response. In formal investigations the handclap is replaced with collection methods that are calibrated and consistent. It is important to understand that regardless of the method used to collect it the impulse response is the most fundamental acoustic test it is the primary means of analyzing the acoustic behavior of a room. The room will have the same effect on any sound coming from the loudspeaker as it does the impulse. The sound fields produced by the impulse include, the direct sound field, the early-reflected sound field, the late sound field, and the reverberant sound field.

For pure acoustics work the impulse may be a balloon pop or starter's pistol. For sound system work the stimulus may be pink noise or a sine wave sweep that is played through a loudspeaker, recorded, and mathematically processed to yield the impulse response by an analyzer. This method allows the impulse response to be collected without using an actual impulse.

This results in dramatically improved signal-to-noise ratio. The room impulse response is shown. It is a time domain plot in which pressure is the dependent variable and time is the independent variable. If you want to know why a room sounds the way that it does you collect and analyze the room impulse response.