Apple Impulse Response Utility - Manual (Page 12)

12
Reverb Time
The Reverb Time parameter determines the maximum recording time for each track. In
order to accurately capture the acoustic properties of a space, you should set a value
that is long enough to capture the decay phase of all reverberations and echoes.
If you are using the sweep generator, the reverb time will start when the sine sweep
ends. If you have the Sweep Length set to Off (in order to record a starter pistol shot
impulse response), the Reverb Time parameter determines the entire length of the
recording.
To set the reverb time:
1 Click inside the Reverb Time display.
2 Do one of the following:
 Drag left (or down) to reduce the time, or right (or up) to increase the time.
 Type a numeric value for the reverb time.
Preroll
You want to be sure that any operator noise, such as typing, readjusting microphones,
and so on, is not recorded. You can set a pre-roll for just this purpose; recording won’t
start immediately, giving you time to finish typing, make last minute mic corrections,
and so on. The pre-roll length equals the time you set with the Reverb Length parameter.
To turn pre-roll on/off:
m Click the pre-roll checkbox.
Test Tone Generator
Impulse Response Utility includes an integrated, sustaining (in other words, non-
sweeping) sine wave tone generator, which helps you to calibrate your hardware
outputs. A number of frequencies are available: 100 Hz, 1 kHz, 5 kHz, and 10 kHz. Use
this test tone to ensure that your hardware output channel is connected properly, and
that your speakers can reproduce the selected sine wave frequency.
To set the frequency of the test tone:
m Choose the desired frequency from the Test Tone menu.
To turn the test tone on/off:
m Click inside the on box.
When the box is checked, you will immediately hear the test tone through the selected
sweep channel.
Note: The level of the test tone is determined by the Sweep Level parameter.