Sound Zone Separation via Head-Position Adaptive Filtering
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Solution Overview
Problem
Existing sound reproduction systems struggle to create distinct sound zones in open rooms without physical separation, as listeners often experience interference from adjacent sound fields due to the complexity of designing effective compensation filters and the limitations of reverberant conditions.
Innovation Solution
A sound system utilizing a multiple-input multiple-output (MIMO) configuration with filtering and optical monitoring to process electrical audio signals into acoustic signals, adjusting filtering characteristics based on the listener's head position, and employing regularization and directional loudspeakers to minimize crosstalk and enhance sound zone separation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If arrays of loudspeakers with preprocessing are used to create sound zones, then multiple regions of different sound material can be reproduced simultaneously, but interference from adjacent sound fields occurs due to reverberant conditions
Solution Approach 1:
The patent divides the acoustic space into multiple distinct sound zones, each with its own audio content. The system segments the sound field by using multiple loudspeaker arrays positioned at different locations, with each array responsible for creating sound in specific zones. This segmentation allows different audio materials to be reproduced simultaneously without interference, as each zone is acoustically isolated through the preprocessing filters that direct sound energy to specific spatial regions.
Solution Approach 2:
The system dynamically adjusts filtering parameters to compensate for the transfer matrix between loudspeakers and listening positions. By changing the frequency response, phase, and time delay parameters of the preprocessing filters, the system adapts to different room acoustics and listener positions. This parameter adjustment minimizes crosstalk between adjacent sound zones by inverting the transfer function matrix, thereby canceling out reverberant interference and achieving clear sound zone separation.
2Adaptability or versatility
If filtering is applied to compensate for transfer matrix, then sound zone separation is improved, but system complexity increases
Solution Approach 1:
The system performs preliminary computation of the transfer matrix and its inverse before actual sound reproduction. The preprocessing filters are designed in advance based on the known or measured acoustic transfer functions between loudspeakers and listening positions. By pre-calculating the filter coefficients that will compensate for the transfer matrix, the system avoids real-time complex computations during playback, thereby reducing operational complexity while maintaining effective sound zone separation.
Solution Approach 2:
The patent introduces a signal processing arrangement as an intermediary between the audio sources and loudspeakers. This intermediary component performs the complex filtering operations, including transfer matrix compensation and sound zone localization. By concentrating the computational complexity in this dedicated intermediary module, the rest of the system (loudspeakers, room, listeners) remains simple and unchanged. The intermediary handles all the mathematical complexity of multi-channel audio processing, making the overall system manageable despite the sophisticated filtering required.
3Adaptability or versatility
If head position monitoring is implemented, then filtering characteristics can be adjusted for optimal sound quality, but measurement and detection difficulty increases
Solution Approach 1:
The system implements a feedback mechanism where the head position of listeners is continuously monitored and used to adjust the filtering characteristics in real-time. Optical sensors or other detection devices track the position of listeners' heads, and this information feeds back to the signal processing arrangement. The system then dynamically adjusts the preprocessing filters to maintain optimal sound zone separation and audio quality as listeners move. This closed-loop feedback ensures that the complex filtering adapts automatically to changing listening conditions without requiring manual intervention.
Solution Approach 2:
The patent replaces complex mechanical position detection systems with optical or electromagnetic sensing methods. Instead of using mechanical encoders, potentiometers, or physical switches to track head position, the system uses optical sensors (such as cameras or infrared detectors) that non-contactlessly and precisely measure the position of listeners' heads. This substitution reduces mechanical complexity, increases measurement accuracy, and allows for continuous, dynamic tracking of head position to adjust filtering characteristics accordingly.
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 creates and maintains distinct sound zones by compensating for transfer matrices and adapting to listener positions, reducing interference and improving sound quality across multiple zones.
Implementation Method 1
The visual monitoring system comprises two optical sensors, of which one is disposed above the listener's head and the other is disposed in front of the listener's head
Implementation Method 2
K groups of loudspeakers that are arranged at positions separate from each other and within or adjacent to the N sound zones, each configured to convert the K processed electrical audio signals into corresponding K acoustic audio signals
Data Source
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AI summary
The system and method for acoustically reproducing Q electrical audio signals (Q = 1, 2, 3, ...) and establishing N sound zones (N = 1, 2, 3 ...), in each of which reception sound signals occur that provide an individual pattern of the reproduced and transmitted Q electrical audio signals, comprise processing the Q electrical audio signals to provide K processed electrical audio signals and converting these K signals into corresponding K acoustic audio signals with K groups of loudspeakers that are arranged at positions separate from each other and within or adjacent to the N sound zones. A position of a listener's head relative to a reference listening position is monitored. Each of the K acoustic audio signals is transferred according to a transfer matrix from to the N sound zones, where they contribute to the corresponding reception sound signals. Processing of the Q electrical audio signals comprises filtering that is configured to compensate for the transfer matrix so that each one of the reception sound signals corresponds to one of the electrical audio signals. Characteristics of the filtering are adjusted based on the identified position of the listener's head.