US Patent 7894621 Audio device comprising a microphone

An audio device includes a microphone, a sound canal allowing sound to pass from the surroundings to the microphone, a signal path from the microphone to a receiver, and a current source, such that sounds received at the microphone may be enhanced and presented at the ear level of the user. A protection screen is provided at the sound canal, and includes a first surface which faces the surroundings and a second surface which faces the sound canal, and defines a slit-formed opening between the first surface and the second surface. The curvature between the first surface and the slit-formed opening is smooth and gradual, and a sharp edge is located at the transition between the second surface and the slit-formed opening.