Abstract:
Methods that use deterministic excitation signals to estimate impulse responses, like MLS and sweep sine, are being used in building acoustics measurement to improve signal-to-noise ratios. The sound pressure levels of the impulse responses can not be associated directly to absolute values after the digital processing steps involved in the estimation. To measure building acoustics properties, normally it’s necessary to account for level differences or rates of level change. This can be done after the impulse response integration. In many cases it’s very convenient to use multi-channel measurement systems, collecting data at several points in a room for spatial averages, or in two rooms for sound isolation measurement. The differences between the channel sensitivities, including the microphone responses, have to be observed. Some procedures for channel adjustment are included in the ISO/DIS 18233, using sound calibrators or by doing comparative measurements with microphones placed close to the excitation source. This work presents experimental results for multi-channel level adjustment using sound calibrators and room measurements. The main purpose is to compare the results obtained by the adjustment methods.
