Creating a Looped Sound

Ansys Sound: Analysis and Specification allows you to use a sample to create a looped sound without any clicks or audio spikes. This is useful for preparing samples for the loopers in Ansys Sound: ASDforEV and for the interpolated samples in Ansys Sound: VR Sound.

To Create a Looped Sound

  1. Load a temporal signal into the Ansys Sound: Analysis and Specification application (see Import Overview).
  2. If necessary, crop the signal to isolate the part of the sound that you wish to loop (see Modifying a Signal with Basic Editing Tools).
  3. In the Tools menu, select Create a looped version (crossfade).
    The Looped signal creation dialog opens. The example waveform image explains how the crossfade is applied.
  4. Set the Crossfade duration to an appropriate value. The minimum value is 10 ms, the maximum value is half the sample duration.
    This parameter controls the ramp duration of the crossfading effect. If the specified value is too short, the crossfading may fail to mask any signal-level mismatches between loops. If it is too long, the crossfading may alter the overall timbre of the sound. In order to minimize energy fluctuations due to the crossfade, the shape of the ramp is a sine branch between 0 and π/2 for the upward ramp, and between π/2 and π for the downward ramp.
  5. Set the Number of test loops parameter to control how many times the sound will loop when testing in this dialog.
  6. Click the Original button to listen to the looped sound without any crossfading. You can click the button again to stop playback.
  7. Click the Crossfaded button to listen to the looped sound with the crossfading applied. You can click the button again to stop playback.
  8. If signal spikes are still audible, try various crossfade duration values and test again, until you can no longer hear them.
  9. Once you are happy with the looped sound, click OK.

A new signal block is created, containing a new sample with crossfading applied as specified above. Note that this new sample will be slightly shorter than the original as result of the crossfading algorithm.