Accessibility audio settings on Apple Watch Ultra
If you prefer to hear a combined left+right audio signal out of both audio channels on speakers or headphones connected to your Apple Watch Ultra, turn on Mono Audio. You can also adjust the left-right balance of your Apple Watch Ultra audio, whether stereo or mono. And you can change AirPods settings to be more accessible.
Change mono audio and balance settings
Open the Settings app 
on your Apple Watch Ultra, tap Accessibility, then, under Hearing, do any of the following:
Switch from stereo to mono audio: Turn on Mono Audio.
Adjust the audio balance: Tap the L or R button below Mono Audio.
You can also open the Apple Watch app on your iPhone, tap My Watch, tap Accessibility, then turn on Mono Audio and adjust the audio balance.
Change AirPods settings
You can change press speed and press-and-hold duration settings for the AirPods you use with your Apple Watch Ultra. You can also turn on noise cancellation on AirPods Pro for when you have one of your AirPods in only one ear.
Open the Settings app
on your Apple Watch Ultra.Go to Accessibility > AirPods, select your AirPods, then choose settings.
You can also open the Apple Watch app on your iPhone, tap My Watch, then go to Accessibility > AirPods.
Show HomePod transcriptions
Apple Watch Ultra can show transcriptions for any HomePod announcements when both devices use the same Apple ID.
Open the Settings app
on your Apple Watch Ultra.Go to Accessibility, then turn on Show Audio Transcriptions.
Turn on headphone notifications
To protect your hearing, your Apple Watch Ultra can send a notification if you’ve been listening to loud headphone audio for long enough to affect your hearing.
Open the Settings app
on your Apple Watch Ultra.Go to Accessibility, then turn on Headphone Notifications.