The stethoscope IR receiver shall be capable of receiving on four (4) carriers (2.3, 2.8, 3.3, 3.8 MHz) and the channel shall be displayed on one (1) of four (4) front panel LEDs. The receiver shall be capable of being locked on a channel. The receiver shall be capable of receiving a stereo signal on each of the four carriers. The receiver shall have a SNR of 60 dB or greater and have built in squelch control. The device shall have an audio frequency response of 63 Hz to 15 kHz, +/- 3db and shall have distortion of less than 2%. The device shall operate for 30 hours with two (2) AAA alkaline batteries and 15 hours with two (2) AAA NiMH rechargeable batteries. The LR-42 is specified.