Abstract: A system and method for adaptively removing feedback in audio systems and, more particularly, hearing aid systems. The audio system comprises an analysis unit, for receiving an input signal and providing N bandpass input signals, and an adaptive feedback cancellation unit for removing a feedback condition in one or more of the N bandpass input signals. The adaptive feedback cancellation unit comprises N sub-units with at least one of the sub-units including: (i) a feedback detector for indicating the presence of the feedback condition in one of the bandpass input signals, (ii) an adaptive feedback canceller for providing an adaptive gain modification factor for adjusting gain when the feedback condition is detected within one of the bandpass input signals, and (iii) a multiplier coupled to the adaptive feedback canceller and the analysis unit for providing a bandpass output signal based on one of the bandpass input signals and the corresponding adaptive gain modification factor.

Abstract: An in-the-canal hearing aid has a shell having an inner end to be positioned in the canal adjacent the user's eardrum, and a faceplate located outwardly of the inner end but still adapted to be recessed within the ear canal in use. A protruding portion of the shell extends outwardly past the faceplate into the concha bowl and serves the dual purpose of both anchoring the hearing aid in the ear so that it cannot work its way down the ear canal, and providing a grip to facilitate insertion and removal of the hearing aid. The protruding portion is preferably cut back close to the faceplate at one side of the faceplate to facilitate battery insertion and removal, and may contain an aperture or a hook-like portion to facilitate gripping. A vent to vent the hearing aid may extend outwardly on the protruding portion to a position adjacent the rim of the protruding portion, to space the outer vent opening away from the microphone opening on the faceplate, to reduce the likelihood of feedback.

Abstract: A wax guard system, for use with an in-the-ear hearing aid, has a housing secured to the hearing aid shell and an insert which screws into the housing. The insert has a body having an internal passage therethrough, and a bridge extending across the exterior opening of the passage. The bridge is higher at its centre than at its ends and carries a thin domed disk which shields the opening and deters wax from entering the passage.

Abstract: A modular hearing aid having separate microphone, receiver, amplifier and battery modules. The microphone module is connected to the receiver module by two dovetails. The receiver module is connected to the amplifier module by one dovetail and to a forwardly projecting plate of the battery module by another dovetail. The amplifier module is connected to the battery module by another dovetail. A flexible circuit board of the amplifier module has a flap which extends over part of the receiver module and is soldered to pins projecting therefrom. The pins extend within the receiver housing and are connected to the receiver therein. Another flap of the circuit board extends over part of the battery module and is soldered to connections on the battery module. Another flexible circuit board extends from the amplifier module over the receiver module and is connected to pins on the microphone module housing. Cover plates cover the top and bottom of the assembled modules to provide a cosmetically attractive appearance.

Abstract: A modular hearing aid to fit in the user's ear, having a shell, a faceplate fixed to the shell, and an electronic module removably snapped into the faceplate. The module includes an open-topped battery compartment which is closed by a lid hinged to the faceplate rather than to the module. This eliminates a bulky hinge on the module and allows a smaller snap fastener between the module and faceplate. The volume control on the module projects through an opening in the closed lid.

Abstract: A method for producing a vent passage for an in-the-ear hearing aid shell. One or more vent holes are drilled in the shell, and a vent tubing having a copper core is laid against the shell interior wall extending through the vent holes. Electricity is passed through the core to heat the vent tubing rapidly (e.g. within 15 seconds) to 60.degree. C. Simultaneously with the heating, acrylic monomer and polymer are mixed. The mixture is poured promptly into the shell over the tubing, and excess mixture is then poured out, after which the coating on the tubing is cured and the tubing is removed. The rapid heating causes onset of polymerization adjacent the tubing but not elsewhere, so that a very compact vent passage is formed with minimal labor and little excess acrylic polymerization in unwanted areas. The heating is performed using a fixture having clamping plates mounted on a rod.

Abstract: A modular hearing aid to fit in the user's ear, having a shell, a faceplate fixed to the shell, and an electronic module removably snapped into the faceplate. The module includes an open-topped battery compartment which is closed by a lid hinged to the faceplate rather than to the module. This eliminates a bulky hinge on the module and allows a smaller snap fastener between the module and faceplate. The volume control on the module projects through an opening in the closed lid.

Abstract: A wax guard for a hearing aid is mushroom-shaped, having a cross passage through its head which intersects an axial passage in its stem. The axial passage contains an acoustic filter terminating the axial passage in its characteristic impedance. The cross passage is semi-circular in section to reduce the projection of the guard into an ear canal and the total area of the two branches of the passage exiting from the axial passage is equal to that of the axial passage. The guard removably snap fits into a metal ring glued into the outlet port of the hearing aid.

Abstract: A connecting cord has a plug at each end. Either such plug may be plugged into the receptacle of a hearing aid and the other plug may be plugged into an external microphone. The contacts of each plug are connected in a different circuit configuration to the conductors of the cord so that when one plug is plugged into the receptacle, the internal hearing aid microphone is shorted out, and when the other plug is plugged into the receptacle, both microphones operate in parallel. The plug contacts are formed of printed circuit board and each plug has a rocker with a hooked top which engages a slot in the receptacle to prevent the inadvertent movement of the plug out of the receptacle. Other plug internal circuit configurations allow connection of other signalling systems to the hearing aid.

Abstract: An acoustical damping element for acoustical tubing such as a hearing aid earpiece, in which a disc of wire screen is positioned over a disc of flexible fabric of a selected acoustic resistance, over the mouth of the tubing. An insertion tool of diameter slightly less than that of the interior passage of the tubing then pushes the composite layers of screen and fabric into the tubing, thereby forming the screen and fabric into closed end concentric cylinders in the passage. The cylindrical sidewall of the screen presses the cylindrical sidewall of the fabric against the interior wall of the tubing to retain the damping element within the passage.

Abstract: A hearing aid having a two port microphone for adjustable directivity. The microphone front port is connected to a front port in the casing by a soft resilient rubber tube. The microphone rear port is connected by another soft resilient rubber tube to an outlet in the top of the casing, which outlet is covered by a slider. The slider has a channel communicating with the outlet and having front and rear openings separated by a divider wall. Depending on the position of the slider, the outlet connects with either the front or rear channel opening, controlling the directivity of the aid. The microphone is supported by the rubber tubes, which isolate it from the remainder of the aid.