Unity/iOS - High Pitched Squeal When Controlling EQ Via Parameter/Velocity

Hi Folks, We’re having an issue when controlling a low pass filter of the Multiband EQ via velocity. The problem only reveals its self on iOS builds, not in FMOD Studio or Unity. We first found the issue using FMOD 1.10, but we’re now on 2.02.04 and it’s still happening.

The EQ band is using the default Q, which is obviously quite subtle, but it almost sounds like the filter is self-oscillating (just a guess).

Thanks, Matt

I have a few questions if you could please clarify:

  • Are you automating the full spectrum of frequency values? i.e
  • Is the low pass filter set to the default of “LP 12dB”?
  • Where does Velocity comes into this? Are you controlling the parameter’s value using a moving object’s velocity vector?

Hi Jeff,

  • The parameter is controlling a range from ~600Hz to 22kHz.
  • I am using the default 12dB filter.
  • And from the dev: The parameter’s value is not being driven by a moving objects’ velocity vector. The Velocity parameter value is controlled by a float variable which increases when the player draws x distance of stroke (input-driven drag callback), and decreases over time to a minimum of 0 (FixedUpdate).

And for a bit more context, the event provides sound when drawing in the sand, and so velocity is tracking that speed.

Thanks, Matt

Thank you for reporting this issue, I have reproduced it as described on iOS and inside FMOD Studio when performing large, instantaneous parameter changes, with more extreme results with 48db highpass and lowpass filters.
I have passed this on to the devlopment team to look into in more detail, in the meantime I have found that this issue does not reproduce with the highshelf filter if you can approximate the desired effect well enough using that?