Well, for starters, the official Google Play Music app (or the Google Apps for Android app) lets you stream your recordings. Other apps (like your PC’s Media Player) also let you stream directly to a phone.
Another option on the Google Play store is the video app from the Media Composer and YouTube apps. However, videos are not supported in this case (see answer to question about running audio on a phone).
Note that you cannot use Google Maps audio (but you can use Maps Photos and Maps Stories).
You can play music over Google Voice (not just recordings) using Google Play Music. In Google Music, you use the Music app to launch the Google Play Music app when you want to use Google Voice. You can also record a phone conversation and send it to the phone with the Google Play Music app. Once you record a phone conversation, you can search the recordings in your phone using the phone call history search.
Can I create my own music in Music?
Music can be created in the Music app (Android) and you can also play music back in the Google Music app. If you would rather create music on your own without having to deal with editing software, the Music app lets you do so. However, most people prefer you to use the Google Music app for play music back.
What’s that song I just downloaded? What is the copyright notice on it? Do I even have to pay for this song, or can I copy it for free?
It’s likely that you downloaded music from another website; you don’t have to pay for it. However, it can get annoying if it gets onto your phone for free and you have to pay for it. You can check your email (on the PC in the usual place) or the Music app to see where the song came from or if you want to download it again, either on your own or copy it to your computer. You can even go to a song’s website and see if you can find the song. It may be worthwhile to sign up for the SongTribe app, either from the computer or phone.
If you downloaded the song in a different way, like by downloading it from a web site (“on-line”) or downloading it to your phone (using the Google Play Music app), it’s unlikely that you can get the copyright notice on the copy. If the music is actually free, you’d probably want to ask the band for permission to use it