Patent ID: 8385563
Filing Date: 2013-02-26
Classification: H03G,H04R

Abstract:
1. A system, comprising: a transducer for converting an electrical signal driving the transducer into audible sound; a phase estimator for estimating an acoustic impedance of a medium acoustically coupled to the transducer by estimating a phase difference between a voltage and a current of the electrical signal driving the transducer; and a sound level control for: in response to the estimated acoustic impedance indicating that the medium is an auditory canal, determining that the transducer is aligned with an ear, and protecting a user from an unsafe level of sound pressure by reducing a loudness of a sound produced by the transducer; and, in response to the estimated acoustic impedance indicating that the medium is other than the auditory canal, determining that the transducer is spaced a safe, distance from the ear.