An earpiece includes: a first end; a second end opposite from the first end; a first channel extending from a first location that is closer to the first end than to the second end, to a second location that is closer to the second end than to the first end; and a first diaphragm, wherein the first diaphragm has a first surface and a second surface opposite the first surface, the first surface of the diaphragm configured to be in fluid communication with a lumen in the first channel, wherein the first diaphragm extends in a direction that is parallel to, or that forms an acute angle with, a longitudinal axis of the first channel.