Sound Image Localization Device Frequency-Dependent Filter Correction
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Solution Overview
Problem
Conventional methods struggle to generate directional sound with high sound quality in a wide frequency band, as they either fail to intentionally design directivity or result in large filter gains, particularly in the low frequency band, making it difficult to reproduce desired directional characteristics and low frequency sounds.
Innovation Solution
A sound image localizing device and method that includes a directivity control filter design unit, filter coefficient correction unit, and convolution operation unit to compute and correct filters for a speaker array, ensuring constant filter gains across frequencies, and using objective functions and constraints to optimize filter coefficients for desired directional characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If directivity control is performed using conventional methods, then directional sound can be generated, but the filter gain becomes large in the low frequency band, making it difficult to reproduce low frequency sounds
Solution Approach 1:
The patent introduces a frequency-dependent regularization parameter λ(ω) that changes based on frequency. For low frequencies where filter gain becomes excessively large, the regularization parameter increases to suppress the filter gain. For high frequencies where directional control is more critical, the regularization parameter decreases to preserve directional characteristics. This parameter change resolves the contradiction by adaptively balancing filter gain and directional precision across different frequency bands.
Solution Approach 2:
The patent makes the regularization parameter dynamic rather than static. The parameter λ(ω) varies with frequency, allowing the system to automatically adjust the balance between filter gain suppression and directional control precision for each frequency component. This dynamic adjustment enables optimal performance across the entire frequency spectrum without compromising low frequency reproduction or directional accuracy.
2Device complexity
If the same regularization parameter is used for all frequencies, then the device complexity is reduced, but the manufacturing precision of directional characteristics deteriorates
Solution Approach 1:
The patent transitions from a static regularization parameter to a frequency-dependent parameter λ(ω). This allows different regularization strengths to be applied automatically at different frequencies without manual configuration. The system computes the optimal regularization parameter for each frequency band, achieving high directional precision while avoiding the complexity of manually configuring multiple parameters.
3Quantity of substance
If filter gain is suppressed using a penalty term, then the low frequency band reproduction is improved, but the directional characteristic reproduction becomes insufficient
Solution Approach 1:
The patent applies frequency-dependent regularization that adapts the balance between filter gain suppression and directional control for each frequency band. At low frequencies, the regularization parameter is large to suppress filter gain and improve reproduction. At high frequencies, the regularization parameter is small to preserve directional characteristics. This frequency-aware adjustment resolves the contradiction by tailoring the suppression strength to the specific frequency band.
Solution Approach 2:
The patent applies different regularization strengths to different frequency bands rather than applying a uniform penalty across all frequencies. Each frequency component receives localized optimization where the regularization parameter is tuned to the specific requirements of that frequency band, allowing low frequency gain suppression without compromising high frequency directional 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
Enables the reproduction of sound in a wide frequency band with high sound quality by generating a virtual speaker using directivity control and reflection from a wall surface, effectively addressing the limitations of conventional methods.
Implementation Method 1
Directivity control technologies are technologies of controlling a direction in which sound strongly propagates from speakers or a direction in which sound does not propagate from the speakers by arranging control points around a speaker array
Implementation Method 2
a virtual speaker is generated by controlling directivity of sound and causing the sound to be reflected from a wall surface through directivity control
Data Source
AI summary
Provided is a sound image localizing device, a sound image localizing method, and a program that enable a virtual speaker to reproduce sound in a wide frequency band with high sound quality. A sound image localizing device 10 includes a directivity control filter design unit 11 that computes a directivity control filter from a desired directional characteristic, a filter coefficient correction unit 12 that corrects the directivity control filter computed by the directivity control filter design unit 11, and a convolution operation unit 13 that computes an output acoustic signal by performing convolution of an input acoustic signal and the directivity control filter corrected by the filter coefficient correction unit 12. Filters that respectively correspond to speakers constituting a speaker array are computed by the directivity control filter design unit 11 and the filter coefficient correction unit 12, an acoustic beam is generated using directivity control by the speaker array, and the acoustic beam is caused to be reflected from a wall surface or a ceiling to generate a virtual sound source.