Sound Field Control Apparatus Using Spatial Transfer Characteristics
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Solution Overview
Problem
In environments where multiple listeners are present, existing sound field control technologies fail to effectively manage sound pressures in different areas, leading to inconsistent audio experiences as listeners may desire varying volume levels.
Innovation Solution
A sound field control apparatus comprising a control filter, two speakers, and a calculation unit that adjusts sound pressure by convoluting filter coefficients with acoustic signals to generate specific sound pressures in targeted areas, allowing for independent control of sound increase, reduction, or maintenance in different zones.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a single loudspeaker transfers sound pressure to multiple areas, then the sound pressure is distributed to all areas, but the sound pressure cannot be independently controlled in each area
Solution Approach 1:
The patent segments the sound field into multiple distinct areas (first area and second area) with separate control points. By dividing the sound field control into independent zones, each area can have its sound pressure controlled separately through dedicated control filters, enabling flexible adaptation to different listener needs without requiring a completely separate speaker system for each area.
Solution Approach 2:
The patent applies local quality by creating area-specific control characteristics where each area has its own transfer function and control parameters. The control filter is designed with area-dependent coefficients that adjust the sound pressure distribution locally, allowing different sound pressure levels in different spatial zones while using a single loudspeaker system.
2Manufacturing precision
If sound pressure is increased in one area, then the volume is sufficient for listeners in that area, but listeners in other areas experience excessive volume
Solution Approach 1:
The patent changes the parameters of the control filter based on the desired sound pressure levels for different areas. By adjusting the filter coefficients according to area-specific transfer functions and sound increase ratios, the system achieves precise sound pressure control in each area. The calculation unit automatically computes the appropriate filter parameters, maintaining precision while simplifying operation.
Solution Approach 2:
The patent incorporates feedback mechanisms where the sound increase ratios for each area are used to adjust the control filter characteristics. The system monitors the required sound pressure adjustments and modifies the filter coefficients accordingly, enabling precise control while reducing the complexity of manual adjustment through automated feedback-based parameter optimization.
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
Enables precise control of sound pressures in multiple areas, allowing for customized audio experiences by adjusting sound increase ratios, ensuring desired volume levels are maintained or increased in specific areas while maintaining or reducing them in others, effectively addressing the variability in listener preferences.
Implementation Method 1
The control filter convolutes a first filter coefficient and a second filter coefficient with a first acoustic signal to generate a second acoustic signal and a third acoustic signal
Data Source
AI summary
A first filter coefficient and a second filter coefficient are calculated by using spatial transfer characteristics from a first speaker and a second speaker to a first control point and a second control point, and a first sound increase ratio na at the first control point and a second sound increase ratio nb at the second control point, so that, when the first filter coefficient is a through characteristic, a first composite sound pressure from the first speaker and the second speaker to the first control point is na times a first sound pressure from the first speaker to the first control point, and a second composite sound pressure from the first speaker and the second speaker to the second control point is nb times a second sound pressure from the first speaker to the second control point.