Method and device for detecting a displacement and movement of a sound producing unit of a woofer

A method for adjusting a response of a loudspeaker system comprising a woofer installed in a housing, said woofer comprising a sound producing unit, the method comprising:

• transmitting an ultrasonic audio signal with an ultrasonic audio transmitter;
• receiving the ultrasonic audio signal with an ultrasonic audio receiver;
• determining with a position detection unit the position of the sound producing unit based on a phase difference between the received ultrasonic audio signal and the transmitted ultrasonic audio signal, said phase difference being dependent on a length of a signal path between the transmitter and the receiver;
• and
• adjusting a spring constant effecting to the sound producing unit of the woofer on the basis of the determined position.

A module to be used in a system comprising a loudspeaker system comprising a woofer installed in a housing, said woofer comprising a sound producing unit, an ultrasonic audio transmitter for transmitting an ultrasonic audio signal;

• and an ultrasonic audio receiver for receiving the ultrasonic audio signal, said module comprising:
• a position detection unit for determining the position of the sound producing unit based on a phase difference between the received ultrasonic audio signal and the ultrasonic audio signal transmitted from the transmitter, said phase difference being dependent on a length of a signal path between the transmitter and the receiver;
• and
• a control unit for adjusting a spring constant effecting to the sound producing unit of the woofer on the basis of the determined position.

A computer program product, comprising:

• a non-transitory computer readable medium;
• and
• computer code recorded on the computer readable medium and executable by a processor for adjusting a response of a loudspeaker system comprising a woofer installed in a housing, said woofer comprising a sound producing unit, the computer code for
• transmitting an ultrasonic audio signal with an ultrasonic audio transmitter;
• receiving the ultrasonic audio signal with an ultrasonic audio receiver;
• determining with a position detection unit the position of the sound producing unit based on a phase difference between the received ultrasonic audio signal and the transmitted ultrasonic audio signal, said phase difference being dependent on a length of a signal path between the transmitter and the receiver;
• and
• adjusting a spring constant effecting to the sound producing unit of the woofer on the basis of the determined position.