Multichannel Audio Compensation for Comb Filtering
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Solution Overview
Problem
Multichannel audio systems in enclosed environments, such as vehicle cabins, suffer from comb filtering effects due to reflective surfaces, leading to deviations in target frequency response, which degrade the listening experience by presenting listeners with both direct and delayed sound, causing constructive and destructive interference.
Innovation Solution
A multichannel compensating audio system that uses series-connected delay, level adjuster, and frequency equalizer circuits to generate compensated audio signals for each channel, which are then electronically summed with other channel signals to minimize comb filtering effects and maintain the perceived origin of sound, ensuring a uniform spectral energy level and minimizing deviations in target frequency response across different listening positions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multichannel audio systems operate in enclosed environments with reflective surfaces, then the system can provide immersive sound experience, but comb filtering effects occur due to constructive and destructive interference between direct and reflected sound
Solution Approach 1:
The system applies preliminary anti-action by introducing compensation signals that preemptively counteract the harmful comb filtering effects before they fully manifest. The compensation channels generate anti-phase signals that cancel out the destructive interference patterns caused by reflected sound, thereby preserving the immersive audio experience while eliminating frequency response deviations
Solution Approach 2:
The system converts the harmful reflected sound into a beneficial element by using the same reflected paths to deliver compensation signals. The compensation channels utilize the existing acoustic environment's reflection characteristics to generate corrective signals that, when combined with direct sound, eliminate comb filtering effects and improve overall frequency response
2Object-affected harmful factors
If compensation channels are added to correct frequency response deviations, then comb filtering effects are reduced, but system complexity increases
Solution Approach 1:
The compensation channels serve multiple functions simultaneously: they generate compensation signals, process them through delay and equalization circuits, and distribute them to appropriate output channels. This multi-functionality allows the system to correct comb filtering across multiple audio channels using a unified compensation architecture, reducing overall system complexity compared to separate correction mechanisms for each channel
Solution Approach 2:
The system merges the compensation signal generation, processing, and distribution functions into an integrated compensation channel structure. The delay circuits, level adjusters, and equalizer circuits are combined in series within each compensation channel, creating a compact modular design that reduces component count and simplifies system implementation while maintaining effective comb filtering correction
3Loss of information
If delayed sound from reflective surfaces is present, then spatial awareness is enhanced, but frequency response deviations occur due to interference patterns
Solution Approach 1:
The system applies partial action by selectively compensating only for the harmful frequency response deviations caused by reflected sound, while leaving the beneficial spatial awareness-enhancing aspects of reflected sound intact. The compensation channels target specific frequency ranges where comb filtering occurs, applying correction only where needed rather than eliminating all reflected sound energy
Solution Approach 2:
The compensation system applies local quality by targeting specific frequency ranges and spatial locations for correction. The equalizer circuits in the compensation channels adjust frequency response locally at problem frequencies, while delay circuits provide location-specific compensation based on the acoustic characteristics of different listening positions, preserving spatial awareness while correcting frequency accuracy
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 system effectively reduces comb filtering effects, ensuring that listeners perceive sound as originating from the intended source, maintaining a consistent spectral energy level and minimizing deviations in target frequency response, even with varying speaker qualities and listening positions, thus enhancing the audio experience.
Implementation Method 1
Each of the one or more compensation channels includes a series connected delay circuit, a level adjuster circuit and frequency equalizer circuit that generates a compensated audio signal from an audio signal on a channel of an input audio signal
Implementation Method 2
Each of the one or more compensation channels includes a series connected delay circuit, a level adjuster circuit and frequency equalizer circuit that generates a compensated audio signal
Implementation Method 3
Each of the one or more compensation channels includes a series connected delay circuit, a level adjuster circuit and frequency equalizer circuit that generates a compensated audio signal
Implementation Method 4
the compensated audio signal is electronically summed with a second audio signal being supplied to the second speaker on the second channel
Implementation Method 5
the listener at the listening location perceptually localizes the origination of the first audio signal as being from the first loudspeaker
Data Source
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AI summary
A multichannel compensating audio system includes first and second compensation channels to psychoacoustically minimize deviations in a target response, to psychoacoustically move the physical position of a speaker and/or to psychoacoustically provide a substantially equal magnitude of sound from a plurality of speakers in a plurality of different listening positions. The first compensation channel may include a series connected delay circuit, a level adjuster circuit and a frequency equalizer circuit that generates a first compensated audio signal from a first audio signal. The second compensation channel may include a series connected delay circuit, a level adjuster circuit and a frequency equalizer circuit that generates a second compensated audio signal from a second audio signal. A first summing circuit is configured to receive at least the first audio signal and the second compensated audio signal and generate a first output signal for provision to a first speaker. A second summing circuit is configured to recieve the second audio signal and the first compensated audio signal and generate a second output signal for provision to a second speaker. The first and second output signals may be output by the first and second speakers into a listening space and are acoustically percieved by a listener.