I have text-to-speech in my app, however when the user puts their phone in their pocket the other play buttons in a list get pressed and multiple streams of audio play. I know I can solve this by the user putting their phone into sleep mode (touch screen inactive), but I don't know how to keep the audio playback going, as it stops when in sleep mode.

I've used apps where I've been able to listen to audio after pressing the sleep button. I cannot find anything in web searches about this.