Abstract: In a battery receiving chamber, the first convex part is formed in the internal side face of the battery compartment and the second convex part which corresponds to the first convex part is formed in the battery cover, the first and second convex part respectively having the inclined faces which gradually rise toward the rotational direction in which the battery cover is detached from the battery compartment, so that a battery receiving chamber having good usage convenience and highly reliable can be realized. Further, in a hearing aid using the above, waterproof means is located so as to block the air vent formed in the battery cover, and a slot connecting the end part of battery cover and the air vent in the external side face of the battery cover is comprised, so that a hearing aid which can supply practically sufficient volume of air into the case and has high waterproof performance can be realized.

Abstract: A hearing aid is used to be inserted into and removed from an ear hole. A cam attached to a taking-out knob pushes up a battery holder by lifting up the taking-out knob when the hearing aid is taken out from an ear hole, whereby the electrode of the battery in the battery holder is left from the battery connecting tongues attached to a panel portion to thereby turn OFF a power supply. A howling prevention fixture is fixed to a hearing aid case at the head portion thereof to prevent howling.

Abstract: A receiving chamber for an air cell battery for use in an electronic device having a casing 2 in which a battery receiving chamber 11 having an open upper end is defined by a wall portion thereof comprises a cover member 13 for selectively closing the open end of the battery receiving chamber, a through-hole 31; 41 formed in the battery receiving chamber for communicating the battery receiving chamber externally, and filter means 32 provided in the through-hole for repelling the water content of air supplied through the through-hole to the battery receiving chamber while allowing air to pass through.