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18.05.2006 Angelo Farina
UNIPR / ASK Industries | All Rights Reserved | Confidential
Modern
electroacoustical methods
§The sound is generated by means of an
omnidirectional loudspeaker
§The signal is computer-generated
§The same computer is also employed for
recording the room’response
by means of one or more omnidirectional microphones
§Also directive microphones can be used:
binaural, figure-of-eight
§Different types of test signals have been
developed, providing good
immunity to background noise and easy deconvolution of the impulse response:
►MLS (Maximum Lenght Sequence, pseudo-random white noise)
►TDS (Time Delay Spectrometry, which basically is simply a linear sine sweep, also known in Japan as “stretched pulse”)
►ESS (Exponential Sine Sweep)
§Each of these test signals can be employed with
different deconvolution
techniques, resulting in a number of “different” measurement methods
§Due to theoretical and practical
considerations, the preference is nowadays generally oriented for the usage of ESS with
not-circular deconvolution