The patent is for an audio player includes an audio headset having two earpieces. A playback circuit provides one of a stereophonic program and a monaural program to the audio headset. The monaural program may be created by mixing channels of the stereophonic program. A mode control is coupled to the playback circuit and to the audio headset. The mode control detects when at least one of the two earpieces is not adjacent a listener's ear and causes the playback circuit to deliver the monaural program to the audio headset. The inventors ar Shaohai Chen, Phillip George Tamchina and Jae Han Lee.

Here's Apple's background and summary of the invention: "A listener may utilize a headset in order to receive an audio program in private and personalized manner. Headsets typically include a right earpiece and a left earpiece coupled to a right and left channel of audio, respectively.

"There may be times when the listener may wish to listen to the audio program with only one of the two earpieces. For example, the listener may wish to leave one ear available for better perception of ambient sounds. As another example, the listener may wish to share the earpieces with a second listener, particularly for headsets of the "ear bud" type, where each listener is listening to the audio program with only one of the two earpieces. It would be desirable to provide a way to effectively use headphones to listen to an audio program with only one of the two earpieces.

"An audio player includes an audio headset having two earpieces. A playback circuit provides one of a stereophonic program and a monaural program to the audio headset. The monaural program may be created by mixing channels of the stereophonic program. A mode control is coupled to the playback circuit and to the audio headset. The mode control detects when at least one of the two earpieces is not adjacent a listener's ear and causes the playback circuit to deliver the monaural program to the audio headset."