Graphical Audio Signal Control for Sound Image Level Adjustment
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Solution Overview
Problem
Existing audio signal processing techniques, such as graphic equalizers, cannot independently adjust the level of a sound with a specific sound image position, leading to unintended changes in sound image positioning when adjusting signal levels across stereo channels.
Innovation Solution
A signal processing apparatus that acquires audio signals from multiple channels, converts them into frequency spectra, calculates frequency-dependent feature amounts, and allows for precise level adjustments within designated regions on a coordinate system, enabling independent amplitude level changes for specific sound image positions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If graphic equalizer adjusts signal level for a particular frequency band, then the level adjustment is applied to all sounds in that frequency band, but it is not possible to adjust the level of a specific sound with a particular sound image position
Solution Approach 1:
The patent segments the frequency spectrum into multiple frequency bands and further segments each frequency band into multiple frequency regions. This hierarchical segmentation allows the system to selectively adjust specific frequency regions within a band, enabling precise control over sounds at different positions while maintaining the ability to perform broad frequency adjustments when needed.
Solution Approach 2:
The patent implements local quality by allowing different adjustment characteristics to be applied to different frequency regions within the same frequency band. Each frequency region can have its own gain settings, enabling the system to enhance or attenuate specific sounds based on their spectral characteristics while leaving other sounds unchanged.
2Ease of operation
If graphic equalizer adjusts signal level independently for L and R channels, then channel-specific level control is achieved, but the sound image position moves to the other channel side
Solution Approach 1:
The patent merges the adjustment of left and right channel signals by calculating the average gain between the two channels for each frequency region. This merging approach ensures that when both channels are adjusted, the sound image position remains stable while the overall level changes, thus achieving level control without unintended position shifts.
3Measurement precision
If frequency-band-by-frequency-band level adjustment is performed, then detailed frequency control is achieved, but all sounds in the frequency band are adjusted uniformly
Solution Approach 1:
The patent divides each frequency band into multiple frequency regions based on spectral characteristics. This segmentation allows the system to selectively adjust specific regions within a frequency band, enabling precise control over different sounds while maintaining detailed frequency control capability.
Solution Approach 2:
The patent dynamically determines the division of frequency regions based on the actual spectral content and characteristics of the audio signal. This dynamic adaptation allows the system to optimize the granularity of frequency regions according to the specific audio material, achieving both precise frequency control and selective sound adjustment.
Data Source
AI summary
Signal processing section of a terminal converts acquired audio signals of a plurality of channels into frequency spectra set, calculates sound image positions corresponding to individual frequency components, and displays, on a display screen, the calculated sound image positions results by use of a coordinate system having coordinate axes of the frequency components and sound image positions. User-designated partial region of the coordinate system is set as a designated region and an amplitude-level adjusting amount is set for the designated region, so that the signal processing section adjusts amplitude levels of frequency components included in the frequency spectra and in the designated region, converts the adjusted frequency components into audio signals and outputs the converted audio signals.