Radial Engineering is now shipping the StageBug SB-7 EarMuff , a headphone interface designed to mute one side of a pair of headphones, allowing musicians recording acoustic instruments or vocals to take off one ear cup, either fully or partially, in order to hear themselves better without causing leakage. Radial describes the product as follows:
"The SB-7 EarMuff begins with a standard ¼" TRS headphone input. A second TRS headphone output on the other side is used to feed the headphones. This is supplemented with a mini 3.5mm TRS jack for those who prefer to use ear buds. As the playback tracks from the recorder are likely in stereo, a MONO SUM switch lets the user blend the left-right signal to mono to ensure all instruments will be heard. A local level control allows the artist to further adjust the volume to suit. A simple LEFT EAR OFF switch is used to mute one side of the headphones. Best of all, the SB-7 EarMuff is completely passive which means it does not require any powering to make it work. You simply plug in and start listening."