Electrodynamic acoustic transducer with magnetic gap sealing

Hearing aid with an electrodynamic acoustic transducer comprising:

• a coil which projects into an air gap formed between an inner surface of a cup and a surface of a pole flange, the coil being subject to an electromagnetic field, wherein the electrodynamic transducer has a membrane including two differently profiled portions, namely an acoustically effective central portion with a convexity in form of a spherical caps and a ring-shaped bead which borders the central portion and serves to elastically support the membrane, the membrane defining a front volume in front of the membrane and a rear volume behind the membrane, wherein the ring-shaped bead is arranged beneath the central portion and extends radially inwards starting from a coil seat of the coil, wherein the air gap is sealed by a liquid or solid medium disposed between an outer surface of the coil and an inner surface of the cup, the liquid or solid medium isolating the front volume from the rear volume of the transducer, and wherein an acoustic short circuit between the front volume and the rear volume of the transducer is prevented.

Headphones with an electrodynamic acoustic transducer comprising:

• a coil which projects into an air gap subject to an electromagnetic field, wherein the electrodynamic transducer has a membrane comprising two differently profiled portions, namely an acoustically effective central portion with a convexity in form of a spherical cap, and a ring-shaped bead which borders the central portion and serves to elastically support the membrane, wherein the ring-shaped bead is arranged beneath the central portion and extends radially inwards starting from a coil seat of the coil, and wherein the air gap is sealed by means of a liquid or solid medium, such that an acoustic short circuit between the front volume and the rear volume of the transducer is prevented.