Recovery of Low Frequency response by
What follows is a preliminary outline of an approach for recovering low frequency system
response form in-room measurement of the system's impulse response, and appropriate
editing of the impulse based on known system parameters. The study is not complete but
represents the first steps in the development of the procedure.
In a typical DIY environment the reflection free portion of the impulse response would likely
extend to 3 or 4 msec. This corresponds to a low frequency limit of 250 to 333 Hz for the
reflection free impulse. Thus, it is anticipated that the long time approximation to the true impulse,
as given by Eq (15b) would be appended to the true impulse some what before 3 or 4 msec. As
an example, using 2.5 msec the "join point" would be at 400 Hz where there is clearly good
agreement between the true impulse and the long time approximation.
Note: The symbol * is used to
denote convolution, not to be
confused with simple