Method and apparatus to create a sound field
First Claim
1. A method of creating a sound field comprising a plurality of channels of sound using an array of output transducers, said method comprising:
- for each channel, selecting a first delay value in respect of each output transducer, said first delay value being chosen in accordance with the position in the array of the respective transducer;
selecting a second delay value for each channel, said second delay value being chosen in accordance with the expected travelling distance of sound waves of that channel from said array to a listener;
obtaining, in respect of each output transducer, a delayed replica of a signal representing each channel, each delayed replica being delayed by a value having a first component comprising said first delay value and a second component comprising said second delay value.
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Abstract
The invention generally relates to a method and apparatus for taking an input signal, replicating it a number of times and modifying each of the replicas before routing them to respective output transducers such that a desired sound field is created. This sound field may comprise a directed beam, focussed beam or a simulated origin. In a first aspect, delays are added to sound channels to remove the effects of different travelling distances. In a second aspect, a delay is added to a video signal to account for the delays added to the sound channels. In a third aspect, different window functions are applied to each channel to give improved flexibility of use. In a fourth aspect, a smaller extent of transducers is used top output high frequencies than are used to output low frequencies. An array having a larger density of transducers near the centre is also provided. In a fifth aspect, a line of elongate transducers is provided to give good directivity in a plane. In a sixth aspect, sound beams are focussed in front or behind surfaces to give different beam widths and simulated origins. In a seventh aspect, a camera is used to indicate where sound is directed.
192 Citations
26 Claims
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1. A method of creating a sound field comprising a plurality of channels of sound using an array of output transducers, said method comprising:
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for each channel, selecting a first delay value in respect of each output transducer, said first delay value being chosen in accordance with the position in the array of the respective transducer; selecting a second delay value for each channel, said second delay value being chosen in accordance with the expected travelling distance of sound waves of that channel from said array to a listener; obtaining, in respect of each output transducer, a delayed replica of a signal representing each channel, each delayed replica being delayed by a value having a first component comprising said first delay value and a second component comprising said second delay value. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
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15. Apparatus for creating a sound field comprising:
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a plurality of inputs for a plurality of respective signals representing different sound channels; an array of output transducers; a replicator arranged to obtain, in respect of each output transducer, a replica of each respective input signal; a first delay element arranged to delay each replica of each signal by a respective first delay value chosen in accordance with the position in the array of the respective output transducer; a second delay element arranged to delay each replica of each signal by a second delay value chosen for each channel in accordance with the expected travelling distance of sound waves of that channel from the array to a listener. - View Dependent Claims (16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26)
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Specification