Claims
- 1. A method of producing a sound recording for playing through a closely-spaced pair of loudspeakers defining with a predetermined listener position an included angle of between 6° and 20° inclusive, filter means being employed in creating said sound recording, the filter means having characteristics which are so chosen that when the sound recordings are played through such a closely-spaced pair of loudspeakers the need to provide a virtual imaging filter means at the inputs to the loudspeakers to create virtual sound sources is avoided, the sound recording being such that when played through the loudspeakers a phase difference between vibrations of the two loudspeakers results where the phase difference varies with frequency from low frequencies where the vibrations are substantially out of phase to high frequencies where the vibrations are in phase, the lowest frequency at which the vibrations are in phase being determined approximately by a ringing frequency, f0 defined by
- 2. A method as claimed in claim 1 wherein the included angle is between 8° and 12°, inclusive.
- 3. A method as claimed in claim 2, wherein the included angle is about 10°.
- 4. A method as claimed in claim 3, in which the filter means is so arranged that the reproduction in the region of the listener's ears of desired signals associated with a virtual source is efficient up to about 4 kHz even when the listener's head is moved 10 cm to the side from the predetermined listener position.
- 5. A method as claimed in claim 1, wherein the out of phase frequency range comprises the range 100 Hz to 4 kHz.
- 6. A method as claimed in claim 1 wherein, in use, the two loudspeakers vibrate substantially in phase with each other when a same input signal is applied to each loudspeaker.
- 7. A method as claimed in claim 6, wherein the input signals to the two loudspeakers are never in phase over a frequency range of 100 Hz to 4 kHz.
- 8. A method as claimed in claim 1 wherein the filter means are designed by employment of least mean squares approximation.
- 9. A method as claimed in claim 8, whereby, in use, substantial minimisation of the squared error between desired ear signals and reproduced ear signals occurs, so that signals reproduced at the listener's ears substantially replicate the waveforms of desired signals.
- 10. A method as claimed in claim 1 in which the filter means is provided with head related transfer function (HRTF) means.
- 11. A method as claimed in claim 10, wherein the head related transfer functions are represented by use of a matrix of filters.
- 12. A method as claimed in claim 1 which is provided with regularisation means operable to limit boosting of predetermined signal frequencies.
- 13. A method as claimed in claim 1 which is provided with modelling delay means.
- 14. A method as claimed claim 1 wherein, in use, the spacing between the centres of the loudspeakers are spaced by no more than about 45 cm.
- 15. A method as claimed in claim 1 wherein, in use, an optimal position for listening is at a head position between 0.2 metres and 4.0 metres from said loudspeakers.
- 16. A method as claimed in claim 15, wherein said head position is between 0.2 metres and 1.0 metres from said loudspeakers.
- 17. A method as claimed in claim 15, wherein said head position is about 2.0 metres from said loudspeakers.
- 18. A method as claimed in claim 1 wherein, in use, the loudspeaker centres are disposed substantially parallel to each other.
- 19. A method as claimed in claim 1 wherein, in use, axes of the loudspeaker centres are inclined to each other, in a convergent manner.
- 20. A method as claimed in claim 1 wherein, in use, the loudspeakers are housed within a single cabinet.
- 21. A method as claimed in claim 1 wherein the filter means comprise two pairs of filters, each of which operates on one channel of a two channel stereophonic sound signals.
- 22. A method as claimed in claim 1 wherein the sound signals are those of a conventional sound recording.
- 23. A sound recording for playing through a closely-spaced pair of loudspeakers defining with a predetermined listener position an included angle of between 6° and 20° inclusive, filter means being employed in creating said sound recording, the filter means having characteristics which are so chosen that, when the sound recording is played through such a closely-spaced pair of loudspeakers, the need to provide a virtual imaging filter means at the inputs to the loudspeakers to create virtual sound sources is avoided, the sound recording being configured such that when played through the loudspeakers a phase difference between vibrations of the two loudspeakers results where the phase difference varies with frequency from low frequencies where the vibrations are substantially out of phase to high frequencies where the vibrations are in phase, the lowest frequency at which the vibrations are in phase being determined approximately by a ringing frequency, f0 defined by
Priority Claims (1)
Number |
Date |
Country |
Kind |
9603236.2 |
Feb 1996 |
GB |
|
CROSS-REFERENCES TO RELATED APPLICATIONS
[0001] This application is a divisional of application Ser. No. 09/125,308, filed Jan. 19, 1999, which is the National Stage of International Application No. PCT/GB97/00415, filed Feb. 19, 1997. All of the above applications are incorporated herein by reference in their entirety.
Divisions (1)
|
Number |
Date |
Country |
Parent |
09125308 |
Jan 1999 |
US |
Child |
10797973 |
Mar 2004 |
US |