Whether you leave music on for your guinea pig depends on a number of factors. Firstly, you should identify if your guinea pig reacts positively to music. If there are any signs of distress you should not be leaving it on for them. If you do decide to leave music on for your guinea pig you should ensure that it is calming, not on too loud, not too close to your guinea pig, and not on for an extended amount of time before you turn it off.