Hi there,
My best guess is that you have your Real Time Audio volume up (off mute) in the editor. When anything in your scene plays sounds and has an audio component set to auto activate, then the sound will play regardless of you pressing play or not. Whether or not you can hear the playing audio is determined by the value of the Real Time Audio slider (aka, sound volume) in the editor settings. If you slide the slider all the way to the left, it will disable real time audio and you won’t hear any audio play until you play the game. See the image below for how to find it.
Hope that helps!