Method for using a mobile device equipped with at least two microphones for determining the direction of loudspeakers in a setup of a surround sound system

Patent metadata

Field	Value
Publication number	US-10104489-B2
Application number	US-201615379633-A
Country	US
Kind code	B2
Filing date	Dec 15, 2016
Priority date	Dec 18, 2015
Publication date	Oct 16, 2018
Grant date	Oct 16, 2018

Abstract

A smartphone having two microphones is used for determining the direction of a loudspeaker in a surround system setup. This is performed using smartphone rotation in azimuth and polar angle direction while capturing in its microphones a test signal from a current one of the loudspeakers. From the microphone signals a corresponding TDOA value is calculated, and the smartphone is rotated until that TDOA value is nearly zero, resulting in a loudspeaker direction information.

First claim

The invention claimed is:

1. A method for using a smartphone equipped with at least two microphones (m 1 ,m 2 ) for determining the direction of loudspeakers A, in a setup of a surround sound system including N loudspeakers, k=1 . . . N, wherein said direction is expressed by an azimuth angle ϕ k and a polar angle θ k , said method including:
a) setting initial values (ϕ 0 ,θ 0 ) for said azimuth angle ϕ k and said polar angle θ k for loudspeaker l k direction;
b) in a first loop over smartphone position angle α for the determination of one of ϕ k and θ k , and thereafter in a second loop over smartphone position angle α for the determination of the other one of ϕ k and θ k :
c) setting k=1;
d) in a sub-loop over k:
e) in a sub-sub-loop over a rotation angle of said smartphone:
f) causing loudspeaker l k to emit a test signal (s k (t));
g) rotating said smartphone and providing for said smartphone a corresponding measured smartphone rotation angle value α k ,
h) capturing corresponding smartphone microphone signals (y k1 (t), y k2 (t)) from said loudspeaker l k test signal;
i) calculating from said microphone signals a corresponding Time Difference of Arrival value (τ k (α k ));
j) if said Time Difference of Arrival value (τ k (α k )) is not zero or is not smaller than a predetermined threshold value, returning to step f);
k) otherwise, calculating a corresponding azimuth ϕ k or polar θ k , respectively, angle value for the position of loudspeaker l k ;
L) incrementing k by ‘1’;
m) if k≤N, returning to step f);
n) otherwise, checking whether both of ϕ k and θ k have been determined, and if not true, returning to step b);
o) after all positions of said N loudspeakers have been determined, providing a corresponding set of N pairs of azimuth and polar angle values ϕ k and θ k for said loudspeakers l k and for all k;
p) using said corresponding set of pairs of azimuth and polar angle values to accurately calibrate said loudspeakers l k .

2. The method for using a smartphone equipped with at least two microphones (m 1 ,m 2 ), having a known distance (d 12 ) from each other, for determining the direction of loudspeakers l k in a setup of a surround sound system including N loudspeakers, k=1 . . . N, wherein said direction is expressed by an azimuth angle ϕ k and a polar angle θ k , said method including:
a) setting initial values (ϕ 0 ,θ 0 ) for said azimuth angle ϕ k and said polar angle θ k for loudspeaker l k direction;
b) in a first loop over smartphone position angle α for the determination of one of ϕ k and θ k , and thereafter in a second loop over smartphone position angle α for the determination of the other one of ϕ k and θ k :
c) positioning said smartphone at a desired azimuth angle or polar angle;
d) setting k=1;
e) in a sub-loop over k:
f) causing loudspeaker l k to emit a test signal (s k (t));
g) capturing the smartphone microphone signals (y k1 (t), y k2 (t)) from said loudspeaker l k test signal;
h) determining from said captured smartphone microphone signals (y k1 (t), y k2 (t)) a loudspeaker distance difference value (Δ k ) and calculating a corresponding smartphone position angle value (α k ):
i) calculating a corresponding azimuth ϕ k or polar θ k , respectively, angle value for the position of loudspeaker l k ;
j) incrementing k by ‘1’;
k) if k≤N, returning to step f);
I) otherwise, checking whether both of ϕ k and θ k , have been determined, and if not true, returning to step b);
m) after all positions of said N loudspeakers have been determined, providing a corresponding set of N pairs of azimuth and polar angle values ϕ k and θ k for said loudspeakers l k and for all k;
n) using said corresponding set of pairs of azimuth and polar angle values to accurately calibrate said loudspeakers l k .

3. The method according to claim 2 , wherein for determining the distance (d 12 ) between said two microphones (m 1 , m 2 ) the following processing is carried out:
a) selecting one loudspeaker l k of said N loudspeakers;
b) causing loudspeaker l k to emit a test signal (s k (t));
c) capturing the smartphone microphone signals (y k1 (t), y k2 (t)) from said loudspeaker l k test signal;
d) rotating said smartphone and providing for said smartphone a corresponding measured smartphone rotation angle value α k ;
e) calculating a corresponding Time Difference of Arrival value (τ k (α k ));
f) if said Time Difference of Arrival value (τ k (α k )) is not zero or is not smaller than a predetermined threshold value, returning to step b);
g) otherwise, defining an initial direction angle value β=0;
h) rotating said smartphone by an angle β≈π/4 and providing for said smartphone a corresponding measured rotation angle value β;
i) causing loudspeaker l k to emit a test signal (s k (t));
j) capturing the smartphone microphone signals (y k1 (t), y k2 (t)) from said loudspeaker l k test signal;
k) calculating from said smartphone microphone signals (y k1 (t),y k2 (t)) a loudspeaker distance difference value Δ k and a microphone distance value

d
12

=

Δ
k

sin
⁢

⁢
β

.

4. The method according to claim 1 , wherein said smartphone includes an app that controls the processing.

5. The method according to claim 2 , wherein smartphone includes an app that controls the processing.

6. The method according to claim 1 , wherein said smartphone microphone signals are
y k1 ( t )= g ( d k1 ) s k ( t−ΔT k1 )+ n 1 ( t ) and
y k2 ( t )= g ( d k2 ) s k ( t−ΔT k2 )+ n 2 ( t ),

wherein ΔT k1 is the time the sound wave needs for propagating from loudspeaker l k to microphone m 1 and ΔT k2 is the time the sound wave needs for propagating from loudspeaker l k to microphone m 2 , S k (∘) is said test signal, g(d k∘ ) is an attenuation factor which describes the dependence of the amplitude on the distance d k∘ between loudspeaker l k and microphone m 1 or m 2 , and n 1 (t) and n 2 (t) take into account environmental and internal noise of said microphones.

7. The method according to claim 2 , wherein said smartphone microphone signals are
y k1 ( t )= g ( d k1 ) s k ( t−ΔT k1 )+ n 1 ( t ) and
y k2 ( t )= g ( d k2 ) s k ( t−ΔT k2 )+ n 2 ( t ),

wherein ΔT k1 is the time the sound wave needs for propagating from loudspeaker l k to microphone m 1 and ΔT k2 is the time the sound wave needs for propagating from loudspeaker l k to microphone m 2 , S k (∘) is said test signal, g(d k∘ ) is an attenuation factor which describes the dependence of the amplitude on the distance d k∘ between loudspeaker l k and microphone m 1 or m 2 , and n 1 (t) and n 2 (t) take into account environmental and internal noise of said microphones.

8. The method according to claim 6 , wherein said Time Difference of Arrival for loudspeaker l k for said smartphone microphones is defined as τ k =ΔT k1 −τ k2 , which corresponds to the spatial difference Δ k =|d k1 −d k2 |=c|τ k | between said smartphone microphones and said loudspeaker l k with the sound velocity c in air as a scaling factor.

9. The method according to claim 3 , wherein said Time Difference of Arrival for loudspeaker l k for said smar

Assignees

• Thomson Licensing

Inventors

• Arnold Michael
• Drexler Michael
• Keiler Florian

Classifications

• H04R29/002

  Loudspeaker arrays · CPC title

• H04S7/301 Primary

  Automatic calibration of stereophonic sound system, e.g. with test microphone · CPC title

• H04R2499/11

  Transducers incorporated or for use in hand-held devices, e.g. mobile phones, PDA's, camera's · CPC title

• H04R5/02

  Spatial or constructional arrangements of loudspeakers · CPC title

• H04R5/04

  Circuit arrangements, {e.g. for selective connection of amplifier inputs/outputs to loudspeakers, for loudspeaker detection, or for adaptation of settings to personal preferences or hearing impairments (combinations of amplifiers H03F3/68; stereophonic systems H04S)} · CPC title