Experimental Investigation of the Statistics of Sound-Power Radiation in a Reverberant Room

The measurement of sound-power injection into a reverberant room is subject to statistical uncertainties owing to the large fluctuations of SPL with variation of source and/or receiver position. Low-frequency pure-tone sources generally require many microphone and source positions if radiated sound power is to be accurately measured. An experimental investigation of low-frequency pure-tone sound radiation into a reverberant room has been conducted using both an 8-in. loudspeaker and a 30-in. loudspeaker at five source positions. The resulting standard deviation of sound-power output of the smaller speaker with source position is in excellent agreement with existing theory if the data is adjusted to account for the finite number of independent microphone readings. Standard deviation of the sound-power output of the larger speaker with source position is significantly lower than the theory at frequencies below 500 Hz. [NASA is acknowledged for partial sponsorship of this work.]