Series X: DIRT 5 and others? Missing some center channel audio in 5.1 and 7.1 mix

Can I ask how you are listening to your audio, Jack? I ask because, depending on the company, the audio is handled in different ways. For example, some companies use the Center Channel on surround sound signals to put out the voices, so if the center channel
has gotten turned down (or if you've chosen the wrong output format in settings) then the game will be trying to play audio on a channel that you don't have hooked up. Say you're listening on a stereo set of headphones, or even just on your TV speakers. If
you set the audio to 5.1 surround, you'll hear SOME audio, because the right and left channels will just be a mix of the different right and left surround channels. But since there is no center channel on a stereo setup, the system will send audio to that
center channel, and your system won't be able to play it. (So, if the audio is directional, any time the voices should be coming from the center speaker, you wouldn't be able to hear them very well.)

You might try setting your audio to Stereo instead of 5.1 or 7.1? It might not be the problem in your case, but it is a possibility worth checking!

The issue is your tv is unable to decode the 5.1 over HDMI. There are 5 channels of audio plus 1 channel for subwoofer they go in this order (Left, right, center, Surround Left, Surround Right). Since your TV is only stereo it's only playing channels 1 and
2, left and right, and commentary is obviously on channel 3 center. Some TV can Downmix, where they take all 5 channels and mix them into 2 stereo channels.

What I would do is set the HDMI back to Stereo so you get the correct 2 channels of audio(the Xbox does the downmix) and then since you are using optical to your surround sound system, set optical to Bitstream and DD 5.1 or DTS is your system supports it.

I figured it out! Audio settings for the Xbox and the TV/stereo/whatever you're getting sound through, need to be the same. If one is set on center channel, but you don't have a center channel speaker, it will sound muffled with low volume. If there is
no center speaker, they both need to be on Stereo instead of 5.1 or 7.1 surround.

Any Matrix does Encoding/Decoding, IceStorm III... As 5.1/7.1 Channels, are being encoded on to 2 channels for a Stereo Headset Playback, as it encodes discrete channels to simulate 5.1/7.1 channel Audio over 2 Speakers when decoding etc...

Unbelievably, the xbox one currently does not support Dolby digital 5.1 or 7.1. There is a Beta setting for surround sound in settings but that doesn't work for me. I get no audio from my center channel. An update is supposedly coming. Thoroughly disappointed.