Patent ID: 8398562

Claim:
A device for parametrically varying air pressure in an ear canal in accordance with the requirements of aural acoustic immittance testing, said device comprising: a first chamber assembly including a first flexible chamber attached, and hermetically sealed, to a first supposing end plate structure, said first flexible chamber enclosing a volume of air which is coupled, via an air line from an air line fitting in said first supporting end plate structure, to an ear canal; a second chamber assembly including a second flexible chamber attached to a second supporting end plate structure, said second flexible chamber enclosing a volume of air coupled via an opening in said second end plate structure to ambient air pressure; a motor assembly including a rigid non ferromagnetic chamber link, said chamber link being fitted on a first end with a first ferromagnetic keeper washer and first rare earth ring magnet, said chamber link being fitted on a second end with a second ferromagnetic keeper washer and second rare earth ring magnet, said first and second ring magnets with like poles magnetically opposing each other whereby the first flexible chamber can be compressed and the second flexible chamber can be expanded, or vice versa, by application of an electromagnetic field which attracts the first ring magnet and repels the second ring magnet, or vice versa; and a forcer assembly, disposed equidistant between the first chamber assembly and the second chamber assembly, said forcer assembly comprising a bobbin formed of a hollow cylindrical ferromagnetic core bounded at either end by ferromagnetic washers, said ferromagnetic core wound with a length of magnet wire to form a coil, said coil providing an electromagnetic field for moving the motor assembly when current flows through said coil.