Method and device for generating information relating to the relative position of a set of at least three acoustic transducers
The invention relates to a method and device for generating data about the mutual position of at least three acoustic transducers. The aim of the invention is to make it possible to continuously measure and calculate the mutual position of at least three acoustic transducers, particularly the rotation and the position of a human head wearing headphones within a room without using any additional transmitter element on the head, headphone, or body of the listener, during audio playback. This aim is achieved by connecting the acoustic transducers to a digitally operated system which comprises an output path emitting audio signals to first and second acoustic transducers, an input path receiving audio signals from the third acoustic transducer, an audio signal source that is connected to the output path, an ultrasound generator that is connected to the output path, and an information generator which indicates a position and is connected to the input path.
1. A method for generating information relating to the relative position of a set of at least three transducers designed for treating acoustic signals, comprising the following steps:
providing a first electric audio signal to a first transducer for transducing the first electric audio signal to a first acoustic signal,
providing a second electric audio signal to a second transducer for transducing the second electric audio signal to a second acoustic signal,
adding a first ultrasonic signal to said first electric audio signal and a second ultrasonic signal to said second electric audio signal before such signals enter said respective first and second transducers,
producing first and second combined acoustical and ultrasonic signals to be emitted from said first and second transducers,
sensing said first and second combined acoustical and ultrasonic signals in a third transducer and converting them into an electrical signal,
filtering out and separating the ultrasonic signals,
producing a first and a second delay signal from said sensed and filtered first and second ultrasonic signals, and
computing from said first and second delay signals a signal representing the relative position of at least one transducer with respect to the at least two other transducers of said set of three transducers.
2. A method according to claim 1 , wherein two transducers of the set are in a fixed positional relationship, further including the step of computing a signal representing the position of at least one transducer with respect to the at least two other transducers and comprising the orientation of said transducers having a fixed relative positional relationship with respect to the third transducer of the set.
3. A method according to claim 2 , wherein the set of transducers comprises four transducers, wherein two transducers for emitting acoustical signals are separated by a fixed first distance, and wherein two transducers for receiving acoustical signals are separated by a fixed second distance, further including the step of computing a signal representing the position and orientation of at least two transducers having a fixed distance in a plane with respect to the at least two other transducers.
4. A method according to claim 3 , wherein the set of transducers comprises five or more transducers, wherein a first group of at least three transducers for emitting or receiving acoustical signals are separated by a fixed first distance, and wherein a second group of at least two transducers for emitting or receiving acoustical signals are separated by a fixed second distance, further including the step of computing a signal representing the position of one group of transducers in space with respect to the other group of transducers.
5. Device for performing the method according to claim 1 , comprising:
a first transducer,
a second transducer,
a third transducer,
a digital system connected to said first, second and third transducers and having an output audio path for feeding audio signals to at least one of said first and second transducers and an input audio path, for receiving audio signals from at least said third transducer,
a source of audio signals connected to said output audio path,
an ultrasonic signal generator connected to the said output audio path in said digital system, and
a position information generator connected to the said input audio path in the said digital system.
6. Device according to claim 5 , further comprising a signal filter and analyzer connected to the position information generator in said input path.
7. Device according to claim 5 , wherein said first and second transducers are part of a headphone and said third transducer is a stationary microphone.
8. Device according to claim 5 , wherein said first and second transducers are stationary loudspeakers and said third transducer is a movable microphone.