User`s manual

Beyond the magnitude frequency response it is also possible to measure the phase
response and the impulse response. When taking acoustical measurements these
functions heavily depend on the interchannel delay i.e. the total amount of delay
present between the two channels, normally due to electronic equipment,
misalignment of sound sources or flight time from speakers to microphone.
When the measurement is just started, if you select the Time data display, you may
see the following impulse response.
The interchannel delay is of about 3.4ms; if you want to measure the phase
response of the system properly you should try to remove it. You can do this in
several manners:
1) Press the Capture delay button; the software should calculate and
automatically remove the delay setting it; you should see the captured delay in the
delay display.
2) Try to input the delay value manually; you can do this clicking on the delay
display and entering the desired value in the resulting dialog.
3) Modify the delay interactively with the keyboard using the PgUp, PgDn (0.1ms
steps) or Shift-PgUp and Shift-PgDn (1 sample steps) keystrokes.
At the end of this process the impulse will be located around zero time.
9 FFT, RTA AND “LIVE” TRANSFER FUNCTION 113