Virtual Speaker Localization Stabilization via Frequency Band Attenuation
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Solution Overview
Problem
Existing virtual surround systems struggle to stabilize the localization sensation of virtual speakers, especially when the volume of one speaker is significantly smaller than the other, leading to unstable sound image positioning.
Innovation Solution
An acoustic signal processing apparatus and method that utilize transaural processing units to generate binaural signals using head-related transfer functions, perform crosstalk correction, and attenuate specific frequency bands to stabilize the localization of virtual speakers by adjusting the acoustic signals and adding auxiliary signals to enhance sound localization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If transaural processing with head-related transfer functions is used to improve localization sensation, then the localization precision is improved, but the device complexity increases due to multiple signal processing paths
Solution Approach 1:
The signal processing is divided into separate frequency band processing paths. The processing unit separates the input signal into multiple frequency bands, applies different processing (transaural processing with HRTF for some bands, attenuation for others) to each band, and then synthesizes them. This segmentation allows complex localization processing to be broken down into manageable frequency-specific operations.
Solution Approach 2:
Different processing methods are applied to different frequency bands based on their specific characteristics. Lower frequency bands that contain notch information critical for localization undergo transaural processing with HRTF, while higher frequency bands are simply attenuated. This local quality approach optimizes processing for each frequency range's specific requirements.
2Adaptability or versatility
If speaker volumes are made unequal to create virtual surround effects, then the adaptability of the virtual surround system is improved, but the stability of localization sensation deteriorates when volume difference is significant
Solution Approach 1:
The system dynamically adjusts processing parameters based on frequency bands. For lower frequency bands containing notch information, transaural processing with HRTF is applied to maintain localization stability. For higher frequency bands, simple attenuation is used. This parameter change approach allows the system to maintain stability across different speaker volume configurations while preserving adaptability.
Solution Approach 2:
The processing unit pre-identifies frequency bands containing notch information in the HRTF and applies appropriate processing to these bands before final synthesis. By preparing and processing critical localization-frequency bands in advance with the correct processing method, the system ensures stable localization sensation is maintained regardless of speaker volume differences.
3Reliability
If frequency bands with notches in HRTF are attenuated to stabilize localization, then the localization stability is improved, but the loss of information in those frequency bands increases
Solution Approach 1:
The processing unit extracts and identifies specific frequency bands that contain notch information in the HRTF. These identified bands are then subjected to transaural processing with HRTF application rather than simple attenuation. This extraction approach allows the system to preserve critical localization information in notch-containing bands while still attenuating other non-critical frequency bands.
Solution Approach 2:
Instead of simply attenuating frequency bands with notches (which would cause information loss), the system converts this potential harm into a benefit by applying transaural processing with HRTF to these specific bands. The notch information, which could be lost through attenuation, is instead preserved and enhanced through HRTF application, improving both localization stability and information retention.
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 solution effectively stabilizes the sound image positioning of virtual speakers even when speaker volumes are uneven, improving the overall localization sensation and widening the configuration variations of the virtual surround system.
Implementation Method 1
a first head-related transfer function between an ear of a listener at the listening position farther from the first virtual sound source and the first virtual sound source
Implementation Method 2
attenuates a component of a first frequency band and a component of a second frequency band in the first input signal or the second binaural signal
Data Source
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AI summary
The present technology relates to an acoustic signal processing apparatus, an acoustic signal processing method and a program which can widen the variations of the configuration of a virtual surround system that stabilizes the localization sensation of a virtual speaker. Crosstalk correction processing is performed on a first binaural signal based on a sound source opposite side HRTF and a second binaural signal based on a sound source side HRTF. A first acoustic signal and a second acoustic signal are generated. A component of a first frequency band, in which a first notch of the sound source opposite side HRTF appears, and a component of a second frequency band, in which a second notch appears, are attenuated in an input signal or the second binaural signal, thereby attenuating the component of the first frequency band and the component of the second frequency band of the first acoustic signal and the second acoustic signal. An auxiliary signal including a component of a third frequency band of the input signal or the second binaural signal, in which the component of the first frequency band and the component of the second frequency band are attenuated, is added to the first acoustic signal, and a third acoustic signal is generated. The present technology can be applied to, for example, an AV amplifier.