Diffusing acoustical crosstalk
AssigneeSTMicroelectronics S.r.l.
InventorEarl C. VICKERS
Life of this patent
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Abstract
When two loudspeakers play the same signal, a “phantom center” image is produced between the speakers. However, this image differs from one produced by a real center speaker. In particular, acoustical crosstalk produces a comb-filtering effect, with cancellations that may be in the frequency range needed for the intelligibility of speech. Methods for using phase decorrelation to fill in these gaps and produce a flatter magnitude response are described, reducing coloration and potentially enhancing dialogue clarity. These methods also improve headphone compatibility and reduce the tendency of the phantom image to move toward the nearest speaker.
Claims31
A method of decorrelating a signal using phase diffusion at high frequencies, the method comprising:
- separating a mono input signal into a high-frequency signal and a low-frequency signal;
- processing the high-frequency signal using a first diffusion means to create a high-frequency left channel signal and a second diffusion means to create a high-frequency right channel signal, wherein a frequency-dependent delay is created between the high-frequency left channel signal and the high-frequency right channel signal;
- processing the low-frequency signal to create a delayed low-frequency signal;
- and
- combining the delayed low-frequency signal with the high-frequency left channel signal and combining the delayed low-frequency signal with the high-frequency right channel signal, thereby producing a stereo response with phase diffusion at high frequencies.
A method of decorrelating a signal using phase diffusion at high frequencies, the method comprising:
- separating a left input signal into a left high-frequency signal and a left low-frequency signal and separating a right input signal into a right high-frequency signal and a right low-frequency signal;
- applying a first diffusion means to the left high-frequency signal, thereby creating a diffused left high-frequency signal;
- applying a second diffusion means to the right high-frequency signal, thereby creating a diffused right high-frequency signal;
- creating a delayed left low-frequency signal and a delayed right low-frequency signal;
- combining the delayed left low-frequency signal with the diffused left high-frequency signal;
- and
- combining the delayed right low-frequency signal with the diffused right high-frequency signal,
- thereby producing a stereo response with phase diffusion at high frequencies.
A system for decorrelating a mono input signal using phase diffusion at high frequencies, the system comprising:
- a high pass filter for outputting a high-frequency signal from the mono input signal;
- a low pass filter for outputting a low-frequency signal from the mono input signal;
- a first diffusion means for creating a high-frequency left channel signal;
- a second diffusion means for creating a high-frequency right channel signal;
- and
- a delay component for creating a delayed low-frequency signal.
A system for decorrelating a stereo input signal having a left input and a right input using phase diffusion at high frequencies, the system comprising:
- a first low pass filter and a first high pass filter, each for processing the left input;
- a second low pass filter and a second high pass filter, each for processing the right input;
- a first diffusion means for creating a high-frequency left channel signal;
- a second diffusion means for creating a high-frequency right channel signal;
- and
- a first delay component for creating a delayed low-frequency left channel signal and a second delay component for creating a delayed low-frequency right channel signal.
Dependencies are inferred from the claim text.