Patent ID: 7764796

Claim:
A control circuit for a signal strength information dependent frequency response adaptation of an audio signal for an electrodynamic transducer, the circuit comprising: a signal strength information determination means for determining a signal strength information according to a level of the audio signal, and a frequency modifying means for selectively modifying the audio signal in response to the signal strength information to adapt the frequency response of the audio signal to the electromechanical properties of the electrodynamic transducer such that the electrodynamic transducer converts the audio signal into a low distortion sound signal for high levels of the audio signal and has a flat frequency response for low levels of the audio signal, wherein a lower frequency range of the audio signal is modified with a gain that is different than a gain of a higher frequency range of the audio signal, and a cutoff frequency separating the lower frequency range from the higher frequency range is shifted towards higher values for an increasing level of the audio signal and towards lower values for a decreasing level of the audio signal, the cutoff frequency being the same or lower than a resonant frequency of the electrodynamic transducer for low-level audio signals.