Now connect one wire to the negative terminal (-) and the other to the positive terminal (+) of the AA battery.

If the speaker cone bulges out (left image), you've got the proper polarity. You now know that the wire on the positive terminal of the AA battery is your "+" wire, i.e. it will connect with the "+" output of your amp.

If the speaker cone moves in (right image), the polarity is reversed. You now know that the wire on the negative terminal of the AA battery would be your "+" wire, i.e. it will connect with the "+" output of your amp.