# US 8,542,854 B2 · Virtual surround for loudspeakers with increased constant directivity

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- Number: US 8,542,854 B2
- Document ID: US8542854B2
- Status: Granted
- Kind: B2
- Application number: 12/717,781
- Filed: 2010-03-04
- Published: 2011-09-08
- Granted: 2013-09-24
- Earliest claimed: 2010-03-04
- Assignees: Logitech Europe S.A.
- Applicants: Jason Riggs; Jason N. Linse; Rong Hu; Joy E. Lyons
- Inventors: Jason Riggs; Jason N. Linse; Rong Hu; Joy E. Lyons
- Web page: https://patentgrep.com/patent/US8542854B2

## CPC

- H04R 1/403: {loud-speakers}
- H04R 5/02: Spatial or constructional arrangements of loudspeakers
- H04R 1/26: Spatial arrangements of separate transducers responsive to two or more frequency ranges
- H04R 1/323: {for loudspeakers (H04R1/34 and H04R1/40 take precedence)}
- H04R 1/345: {for loudspeakers}
- H04R 3/12: for distributing signals to two or more loudspeakers {(specially adapted for hearing aids H04R25/407)}
- H04R 2201/401: 2D or 3D arrays of transducers
- H04R 2203/12: Beamforming aspects for stereophonic sound reproduction with loudspeaker arrays
- H04R 2205/022: Plurality of transducers corresponding to a plurality of sound channels in each earpiece of headphones or in a single enclosure
- H04R 2499/15: Transducers incorporated in visual displaying devices, e.g. televisions, computer displays, laptops
- H04R: LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; ELECTRIC HEARING AIDS; PUBLIC ADDRESS SYSTEMS (producing sounds with frequency not determined by supply frequency G10K)

## Abstract

Various embodiments use combinations of different methods for creating virtual surround. Some of the methods used in various embodiments include: dipole beamforming, multi-stage arrays, transducer directionality, and enclosure shading. In general, each of these methods may operate over a specific frequency band in various embodiments. The use of multiple methods to create virtual sound can increase the virtual sound effect and better maintain sound quality compared to the use of a single method for creating virtual surround. Each method used to create virtual surround can be optimized for a specific system configuration based on factors such as the physical set-up of the transducers, the size and shape of the enclosure, and the input signal configuration. Various embodiments allow for an intensity difference to be created for a listener across a wide range of frequencies in order to produce constant directionality.

## Claims

### Claim 1

A speaker system comprising:
at least one speaker enclosure having a front face;
a plurality of transducers mounted in the at least one speaker enclosure;
at least two of said transducers forming a horizontally displaced array;
a speaker input port;
a controller operatively coupled with said speaker input port;
said controller configured to provide high frequency signals to a high frequency transducer, wherein said high frequency transducer is a side firing transducer;
said high frequency transducer being positioned in said enclosure so that the center line of a sound beam emitted from said enclosure is at an angle to said front face of said enclosure;
wherein said controller is further configured to provide lower frequency signals to said transducers forming the horizontally displaced array to cause dipole beamforming; and
wherein said low frequency signals are determined by dipole beamforming array quarter-wavelength spacing, wherein an array usable frequency region is within +/−2 octaves about the array center frequency f_c, where f_c=c/(4d).

### Claim 2 (depends on 1)

The speaker system of claim 1 wherein said controller is configured to create virtual surround sound.

### Claim 3 (depends on 1)

The speaker system of claim 1 wherein said controller is configured to create stereo sound.

### Claim 4 (depends on 1)

The speaker system of claim 1 wherein said angle is between 30 degrees and 110 degrees.

### Claim 5 (depends on 1)

The speaker system of claim 1 wherein said high frequency signals are determined by F_et=(0.6*c)/(2*π*R_t).

### Claim 6 (depends on 1)

The speaker system of claim 1 wherein said controller is configured to provide low frequency signals and medium frequency signals to at least one transducer other than the high frequency transducer.

### Claim 7 (depends on 1)

The speaker system of claim 1 further comprising:
said high frequency transducer being further positioned to take advantage of shading caused by at least one of a baffle, a waveguide, a lens, or a side of the speaker enclosure.

### Claim 8 (depends on 1)

The speaker system of claim 1 further wherein said horizontally displaced array is a first array and further comprising:
at least a second array of horizontally displaced transducers; and
said controller configured to provide signals to said transducers such that said first and second arrays of horizontally displaced transducers are tuned to different center frequencies.

### Claim 9 (depends on 1)

The speaker system of claim 1 wherein said controller comprises a digital signal processor.

### Claim 10 (depends on 1)

The speaker system of claim 1 wherein said controller comprises analog circuitry.

### Claim 11 (depends on 1)

The speaker system of claim 1 wherein said controller comprises:
a computer readable medium comprising instructions executable by a processor of a computer, the computer readable medium comprising instructions for:
providing high frequency signals to a high frequency transducer, said high frequency transducer being positioned in said enclosure so that the center line of a sound beam emitted from said enclosure is at an angle to said front face of said enclosure; and
providing low frequency signals to said transducers forming the horizontally displaced array to cause dipole beamforming.