UE5 | Stereo sound appears mono when facing it, then stereo when looking away from it


I’m using FMOD with Unreal Engine 5. My issue is that stereo events sound mono when the listener is facing it. When the listener “turns away” (90° to the left or right, so that the view angle is perpendicular to the line between listener and event), the sound spreads out to stereo.

Steps to reproduce:

1.) Create an event in FMOD Studio with a stereo test sound with (noticeably) different audio on the left and right channels. I’m using a stereo sound with two different voices, one using the left channel and one using the right.

2.) Set Min & Max Distance to 3m / 20m.

3.) Set Sound Size to 6m and Min Extent to anything between 0° and 180°. It doesn’t affect the observation. (Setting it to 360° makes it 100% widely spread stereo all the time, but that kills the spacial effect.)

4.) Place the event in an UE5 environment. (The effect cannot be observed in FMOD Studio during design-time.)

5.) Approach the sound source, facing it. You will notice it appears mono, the left and right channels are mixed in the center with no stereo spread.

6.) Turn the camera by 90° to the left or right so that the sound source is now either to the hard left or hard right of the listener.

7.) Notice that the sound now appears stereo and fully spread across both speakers.

I don’t understand why the relative orientation has this counter-intuitive effect. I’d expect the sound to be “most widely spread” when looking at it, and narrowed down to mono / hard left or right when looking away to the side. But that’s apparently not what happens.

Unfortunately, I cannot provide any demo content. I might be able to record a screen capture video if you won’t be able to do the steps above easily. (Will have to ask.)

Thank you very much in advance, I appreciate your help.

1 Like


Apologies for the delayed response.

Thank you for the detailed reproduction steps. I can reproduce a similar behaviour but I am unsure if it is the same as you described. Could I please get a video recording of both the FMOD Studio event, mixer, and the Unreal project? This can either be uploaded to your profile or DM’d to me if you do not wish to share it on the forum.

1 Like

Thank you very much, Connor. And no worries about the delay. The task at hand - including all the steps to reproduce - is quite lengthy, given the little insight into our actual project I’ve provided (so far). So I appreciate your help.

The team and I are currently investigating whether something as simple as a mismatch of the speaker configuration (stereo vs. 5.1) might be the issue. So the cause of the observed behavior might be that due to the lack of a center speaker, the output dedicated for the center is instead sent to both the left and right speakers. The exact same sound, that is. Which would explain the mono-y-ness. We’ve realized that the effect occurs when we use a stereo setup but the engine settings are set to 5.1, regardless of the FMOD build settings. (Or vice versa?)

I’ll post an update here if we could successfully narrow it down, otherwise I’ll send a screen recording.

Thanks again and all the best.

1 Like


Thanks for sharing the information. I was confused by a similar situation while trying to reproduce this. In my case, I had Spatial Sound enabled in my Audio Settings:

Maybe there is a setting somewhere that is adding to the strangeness?

Keep me in the loop if there is anything else I can do.

1 Like