You can listen to tracks individually by clicking their respective Solo buttons (headset icon). The regions on the other tracks will be temporarily muted (greyed out). Deactivate all Solo buttons by pressing Ctrl/Cmd and then clicking on any one of them.
Click the Mute button/speaker icon (a crossed-out speaker icon means the track is muted). In a similar way, you can mute several tracks by clicking their respective Mute buttons and unmute them by pressing Ctrl/Cmd-clicking any one of them.