System and method for enhanced subjective stereo audio
View Patent ↗The present invention relates to an audio communication system and method with improved acoustic characteristics. The present invention utilizes the Haas effect to simulate a sound picture that gives a better subjective impression of stereo sound compared to the objective stereo image. It provides a system and a method for presenting the stereo image in an optimal way for an associated echo canceller without compromising with the subjective perception of stereo.
1. An audio echo canceller system adjusted to provide an echo attenuated output signal from an echo added input signal including near-end audio in addition to an echo contribution originating from a far-end audio presenter unit receiving a left (L) and a right (R) audio signal, wherein the echo attenuated output signal is generated by attenuating the echo in the echo added input signal by a linear adaptive filter, the far-end audio presenter unit comprising:
a first adder configured to add L and R creating a non-delayed mono signal,
a delay unit configured to delay said non-delayed mono signal with a predefined time creating a delayed mono signal being loaded into one or more main loudspeakers, and
one or more left and one or more right loudspeakers into which a first and a second L or R deduced signal, respectively, are loaded,
wherein said non-delayed mono-signal is used as a reference signal for the linear adaptive filter.
2. The audio echo canceller system according to claim 1 , wherein said delay unit is integrated in a first filter (H m ) following said first adder.
3. The audio echo canceller system according to claim 2 , further comprising:
a second adder configured to add R filtered by a second filter (H c ) with L filtered by a third filter (H d ) to create said first L or R deduced signal, and
a third adder configured to add L filtered by said second filter (H c ) with R filtered by said third filter (H d ) creating said second L or R deduced signal.
4. The audio echo canceller system according to claim 1 , further comprising an attenuator, following said first adder, configured to multiply first adder output with ½ to form said non-delayed mono signal.
5. The audio echo canceller system according to claim 1 or 4 , wherein the first and second L or R deduced signal are multiplied with a first gain G i , respectively, before being loaded into said one or more left and one or more right loudspeakers.
6. The audio echo canceller system according to claim 5 , wherein the first L or R deduced signal is L, and the second L or R deduced signal is R.
7. The audio echo canceller system according to claim 5 , further comprising:
a first subtractor, creating the first L or R deduced signal, configured to subtract said non-delayed mono signal multiplied with a second gain G e from L, and
a second subtractor, creating the second L or R deduced signal, configured to subtract said non-delayed mono signal multiplied with the second gain G e from R.
8. A method in an audio echo canceller system providing an echo attenuated output signal from an echo added input signal including near-end audio in addition to an echo contribution originating from a far-end audio presenter unit receiving a left (L) and a right (R) audio signal, comprising:
attenuating the echo in the echo added input signal by using a linear adaptive filter;
adding L and R to create a non-delayed mono signal,
delaying said non-delayed mono signal with a predefined time to create a delayed mono signal being loaded into a one or more main loudspeakers,
respectively loading a first and a second L or R deduced signal into one or more left and one or more right loudspeakers, and
using said non-delayed mono signal as a reference signal for the linear adaptive filter.
9. The method according to claim 8 , wherein said step of delaying is carried out in a first filter (H m ).
10. The method according to claim 8 or 9 , further comprising:
adding R filtered by a second filter (H c ) with L filtered by a third filter (H d ) to create said first L or R deduced signal, and
adding L filtered by said second filter (H c ) with R filtered by said third filter (H d ) to create said second L or R deduced signal.
11. The method according to claim 8 , wherein the step of adding L and R to create a non-delayed mono signal further includes attenuating the result with ½ to form said non-delayed mono signal.
12. The method according to claim 8 or 11 , further comprising:
respectively multiplying the first and second L or R deduced signal with a first gain G i before being loaded into said one or more left and one or more right loudspeakers.
13. A method according to claim 12 , wherein the first L or R deduced signal is L, and the second L or R deduced signal is R.
14. The method according to claim 12 , further comprising:
subtracting said non-delayed mono signal multiplied with a second gain G e from L, to create the first L or R deduced signal, subtracting said non-delayed mono signal multiplied with the second gain G e from R, to create the second L or R deduced signal.