iOS 15
Play background sounds on iPod touch to mask environmental noise
You can play calming sounds—such as ocean or rain—to mask unwanted environmental noise and help minimize distractions so you can focus or rest.
Go to Settings
> Accessibility > Audio/Visual > Background Sounds, then turn on Background Sounds.Set any of the following:
Sound: Choose a sound; the audio file downloads to your iPod touch.
Volume: Drag the slider.
Use When Media is Playing: Adjust the volume of the background sound when iPod touch is playing music or other media.
Stop Sounds When Locked: Background sounds stop playing when iPod touch is locked.