Sound Zone Arrangement with Zonewise Speech Suppression
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Solution Overview
Problem
Existing sound zone arrangements in vehicles face challenges in optimizing speech suppression between closely disposed sound zones, particularly in vehicle interiors, where listeners can often hear speech from adjacent zones intended to be confidential, due to limitations in active noise control systems and the difficulty in achieving sufficient cross-talk cancellation (CTC) bandwidth.
Innovation Solution
A sound zone arrangement that includes a multiplicity of loudspeakers and microphones, along with a signal processing module configured to establish separate sound zones and generate a masking signal using psychoacoustic and speech intelligibility models to reduce common speech intelligibility, employing a MIMO system and acoustic echo cancellation to project a masking signal that effectively suppresses speech intelligibility in unintended zones.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If active noise control systems are used to establish sound zones, then speech privacy can be improved, but the system complexity and difficulty of optimizing cancellation increase significantly
Solution Approach 1:
The patent introduces speech masking signals as an intermediary element between the speaker and the listener. Instead of directly canceling speech through complex active noise control, the system generates masking signals that contain phonemes resembling human speech with matching pitch, volume, and phonetic content. These masking signals are broadcast through loudspeakers to prevent listeners from understanding confidential conversations, thereby achieving speech privacy through a less complex intermediary mechanism rather than direct active cancellation.
2Area of stationary object
If closely disposed sound zones are established in vehicle interiors, then spatial efficiency is improved, but the ability to achieve sufficient cross-talk cancellation bandwidth deteriorates
Solution Approach 1:
The patent changes the parameters of the acoustic environment by introducing speech masking signals with specific phonetic content, pitch, and volume characteristics. Rather than attempting to achieve perfect cancellation across all frequencies in closely spaced zones, the system modifies the acoustic parameters by adding masking signals that selectively prevent speech intelligibility. This approach allows closely disposed sound zones to maintain their spatial efficiency while achieving sufficient privacy through parameter-based masking rather than broadband cancellation.
3Reliability
If speech masking signals are generated using psychoacoustic models, then speech intelligibility suppression is improved, but processing requirements and computational load increase
Solution Approach 1:
The patent utilizes psychoacoustic parameters such as pitch, volume, and phonetic content as key characteristics for generating masking signals. By focusing on these specific perceptual parameters rather than processing the entire speech spectrum, the system achieves effective speech intelligibility suppression. The masking signals are designed to match the phonetic structure and acoustic parameters of human speech, allowing the system to target critical intelligibility factors with reduced computational complexity compared to full-spectrum speech processing.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution effectively reduces speech intelligibility between sound zones to a level where confidential conversations remain unintelligible, enhancing privacy by achieving a sufficient masking effect within the constraints of available processing time and bandwidth.
Implementation Method 1
Active noise control may be used to generate sound waves or 'anti noise' that destructively interferes with unuseful sound waves. The destructively interfering sound waves may be produced through a loudspeaker to combine with the unuseful sound waves in an attempt to cancel the unuseful noise.
Implementation Method 2
An active noise control system generally includes one or more microphones to detect sound within an area that is targeted for destructive interference. The detected sound is used as a feedback error signal.
Data Source
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AI summary
A system and method for arranging sound zones in a room including a listener's position and a speaker's position with a multiplicity of loudspeakers disposed in the room and a multiplicity of microphones disposed in the room includes establishing, in connection with the multiplicity of loudspeakers, a first sound zone around the listener's position and a second sound zone around the speaker's position, and determining, in connection with the multiplicity of microphones, parameters of sound conditions present in the first sound zone. The method further includes generating in the first sound zone, in connection with the multiplicity of loudspeakers, and based on the determined sound conditions in the first sound zone, speech masking sound that is configured to reduce common speech intelligibility in the second sound zone.