Discussion on performance assessment of anechoic rooms

The performance of the anechoic and hemi-anechoic room is assessed by comparing the spatial decrease of sound pressure emitted from a test source with the decrease of sound pressure with distance from the source according the inverse square law that would occur in true anechoic or hemi-anechoic field.When JJF 1147-2006 calibration specification for acoustic performance of anechoic rooms and hemi-anechoic rooms is applied in practice,some unreasonable phenomenon will occur and make the assessment difficult or even impossible.Experimental data analyses show using the least sum of reciprocal of sound pressure as judgment in least square method in JJG 1147-2006 is not appropriate and is the main cause for unreasonable phenomenon occurred.Therefore,two improved methods were suggested.