To have audio in your scene you need at least two objects: an audio source and an audio listener. The audio source is the object that emits the sound and the audio listener is the object that receives the sound.

Any object in your scene can be turned into an audio source or listener by attaching the corresponding component to it. However, you will notice that the Main Camera always comes with an Audio Listener component automatically added to it when a new scene is created. The following screenshot shows the Inspector for the Main Camera from our BattleScene:

Since we will be working in a 2D game the object that we use as our audio source is not terribly important. If we were working in a 3D game and wanted our sound to be 3D (that is, the distance the object is away from the audio listener will affect the sound's volume), we'd want the object actually making the sound to be the audio source.

My preference is to have two objects in my game that are carried...