New Littmann Electronic Stethoscope Model 3000 with breakthrough Ambient Noise Reduction Technology from 3M. The breakthrough technology represents a key milestone in the area of acoustic sensitivity that can be critical to proper clinical diagnosis and quality auscultation. Reducing ambient room noise requires eliminating the noise when it is in the air and when it travels through the patient’s body. ANR technology successfully addresses this issue without filtering out important sounds. Noise from the room enters the stethoscope through a thin gap in the chestpiece. Once inside, this noise meets the ambient noise that has traveled through the patient’s body and entered the chestpiece through the diaphragm. The ambient noise, traveling the two pathways, cancels itself out, leaving only the heart and lung sounds clinicians need to hear.