Adaptive Bass Management Phase Modulation
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Solution Overview
Problem
Current methods for acoustically optimizing audio systems, particularly in small reflective areas like vehicles, are either complex, costly, or ineffective in achieving uniform sound pressure levels across different listening locations, especially in the bass frequency range, due to standing waves and varying acoustic properties.
Innovation Solution
A method involving two loudspeakers with one having a phase-modifying supply channel, where the phase function is adjusted to equalize sound pressure levels by calculating an optimum phase shift based on measured sound pressure levels and transfer characteristics, using a cost function to minimize differences between listening locations and a target sound pressure level.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If manual acoustic optimization is performed by experienced acousticians, then good acoustic results can be achieved, but the process is complex and time-consuming
Solution Approach 1:
The system performs self-optimization by automatically measuring sound pressure levels at multiple listening positions and calculating optimal phase functions without requiring manual intervention by acousticians. The automated bass management system adjusts phase parameters based on measured acoustic characteristics, enabling the system to optimize itself
Solution Approach 2:
The patent replaces manual acoustic measurement and adjustment processes with automated electronic systems that use microphones to measure sound pressure levels and digital signal processing to calculate and apply optimal phase functions, substituting the mechanical/manual optimization process with an automated control system
2Extent of automation
If automated audio tuning systems are implemented, then manual optimization can be replaced, but the systems are extremely complex and costly
Solution Approach 1:
The patent extracts and addresses only the specific problem of bass frequency optimization rather than implementing a complete automated audio tuning system. By focusing solely on phase adjustment in the bass range (20-200 Hz), the system achieves automation without the complexity of comprehensive audio optimization
Solution Approach 2:
The optimization process is segmented into specific frequency ranges, with the patent focusing on bass frequencies (20-200 Hz). This segmentation allows the system to achieve effective automation for the critical bass range without requiring complex processing across the entire audio spectrum
3Measurement precision
If wave-field synthesis is used to model acoustics, then accurate acoustic modeling is achieved, but extensive resources such as computation power and loudspeakers are required
Solution Approach 1:
The patent applies partial action by implementing acoustic optimization only for the bass frequency range (20-200 Hz) rather than across the entire audio spectrum. This partial approach achieves effective acoustic optimization for the most critical low frequencies without requiring the extensive resources needed for full-spectrum wave-field synthesis
Solution Approach 2:
The system changes the approach from comprehensive spatial acoustic modeling to a simplified parameter-based optimization that adjusts phase functions for bass frequencies. By focusing on phase parameter adjustment rather than full wave-field synthesis, the system achieves effective bass optimization with minimal computational resources
4Ease of operation
If phase functions are adjusted to equalize sound pressure levels, then uniform audio perception across listening locations is improved, but the system must continuously adapt to acoustic variations
Solution Approach 1:
The system implements feedback by continuously measuring sound pressure levels at multiple listening positions using microphones and using these measurements to calculate updated optimal phase functions. This closed-loop feedback mechanism enables the system to adapt to acoustic variations and maintain uniform audio perception across different listening locations
Solution Approach 2:
The patent implements dynamic adaptation by allowing the phase functions to be continuously updated based on measured acoustic conditions. The system transitions from static phase adjustment to dynamic adaptation, where phase parameters are adjusted in response to changing acoustic environments and listening conditions
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
This approach effectively equalizes sound pressure levels across different listening locations, improving audio perception by reducing discrepancies in the bass frequency range and adapting to changes in the acoustic environment, thus enhancing room acoustics without the need for extensive resources or manual tuning.
Implementation Method 1
at least the supply channel of the second loudspeaker comprises means for modifying the phase of an audio signal transmitted therethrough according to a phase function
Implementation Method 2
a first and a second loudspeaker for generating an acoustic sound signal from an audio signal
Implementation Method 3
measuring the acoustic sound signal at each listening location and providing corresponding electrical signals representing the measured acoustic sound signal
Data Source
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AI summary
The invention relates to a novel method for adapting sound pressure levels in at least one listening location, the sound pressure being generated by a first and a second loudspeaker, each loudspeaker having a supply channel arranged upstream thereto, where at least the supply channel of the second loudspeaker comprises means for modifying the phase of an audio signal transmitted therethrough according to a phase function. The method comprises: Supplying an audio signal to the supply channels and thus generating an acoustic sound signal; Measuring the acoustic sound signal at each listening location and providing corresponding electrical signals representing the measured acoustic sound signal; Estimating updated transfer characteristics for each pair of loudspeaker and listening location; Calculating an optimum offset phase function based on a mathematical model using the estimated transfer characteristics; Updating the phase function by superposing the optimal offset phase function thereto.