Phase Filter Determination for Multi-Position Vibration Systems
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Solution Overview
Problem
In multichannel vibration systems, phase shifts caused by non-equidistant listener positions lead to unwanted effects, such as deteriorated sound reproduction, as existing solutions like signal delays or phase shift distribution are not satisfactory for multiple listening positions.
Innovation Solution
A method for determining a phase filter by performing spectral measurements for various phase shift values across different frequencies, selecting optimal phase shifts to minimize phase shifts' impact on sound pressure, and applying these to electroacoustic transducers to improve spatial rendering and sound reproduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a simple delay is applied to signals sent to the electroacoustic transducer closer to the listener, then the sounds generated by both transducers reach the listener substantially in phase, but the application of a delay is not always satisfactory and can improve listening in one listening position but deteriorate listening in another listening position
Solution Approach 1:
The patent applies frequency-dependent phase shifts rather than simple time delays. By varying the phase shift parameter across different frequencies according to measured transfer functions, the system achieves accurate phase alignment at multiple listening positions simultaneously, resolving the contradiction between phase alignment accuracy and adaptability to different listening positions.
Solution Approach 2:
The patent uses measured transfer functions from multiple listening positions to determine optimal phase shifts. This feedback approach allows the system to adapt the phase filtering parameters based on actual acoustic measurements, achieving satisfactory sound reproduction across different listening positions rather than optimizing for a single position.
2Measurement precision
If phase shift distribution is applied as disclosed in U.S. Pat. No. 5,033,092A1, then the phase shift is distributed between two channels, but this solution does not address multiple listening positions effectively
Solution Approach 1:
The patent extends phase shift control from a single fixed value or simple distribution to frequency-dependent phase shifts determined by measured transfer functions. This allows the phase shift parameter to vary across frequencies and be optimized for multiple listening positions, overcoming the limitations of simple phase shift distribution.
Solution Approach 2:
The patent determines phase shifts for each frequency independently based on measured transfer functions at multiple listening positions. This segmentation of the frequency spectrum allows precise control of phase relationships at each frequency, achieving better overall performance across multiple positions than uniform phase shift distribution.
3Adaptability or versatility
If spectral measurements are performed for multiple phase shift values and optimal phase shifts are selected for each frequency, then sound reproduction is optimized across multiple listening positions, but the measurement and determination process becomes more complex
Solution Approach 1:
The patent performs spectral measurements and determines optimal phase shifts in advance during a calibration phase. By pre-determining the phase filter parameters based on measurements at multiple listening positions, the system avoids complex real-time calculations during operation, reducing processing complexity while maintaining high adaptability.
Solution Approach 2:
The patent uses transfer function measurements to create a model of the acoustic environment. This copied representation allows the system to determine optimal phase shifts without performing complex real-time optimization, simplifying the operational complexity while maintaining accuracy across multiple listening positions.
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 method enhances sound reproduction by optimizing sound pressure across multiple listening positions, reducing artifacts and improving spatial rendering, while maintaining satisfactory sound quality for both on and off-centered listeners.
Implementation Method 1
a first transducer for converting the first electrical signal into vibrations perceptible by a user and a second transducer for converting the second electrical signal into vibrations perceptible by a user
Data Source
AI summary
A determining method that makes it possible to determine a phase filter for a system that generates vibrations and that includes a first transducer for converting a first electrical signal and a second transducer for converting a second electrical signal. The method includes: performing, for at least one perception position, of a plurality of spectral measurements of a characteristic parameter of the vibrations generated in this perception position as a function of the frequency, each spectral measurement being done for a respective phase shift value between the first electrical signal and the second electrical signal; and determining a phase filter from spectral measurements done, by selecting, for each frequency, a phase shift value from among the phase shift values used to perform the spectral measurements.