Cross-Difference Audio Filtering for Wider Sound Stage Control
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Solution Overview
Problem
Existing sound stage expansion techniques in audio systems fail to effectively mitigate center audio image variation and control treble boost, leading to distracting high-frequency increases and reduced perception of sound stage expansion.
Innovation Solution
The proposed apparatus employs a system with differential amplifier units and cross differencing filter units that allow for the adjustment of center audio images and treble response, using capacitive and resistive networks to manage signal processing and prevent gain increases at higher frequencies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If sound stage expansion techniques are applied to make the sound stage seem wider, then the perceived sound stage width is improved, but center audio image variation occurs and voices are displaced from their sources
Solution Approach 1:
The patent applies parameter changes by modifying the audio signal parameters through filtering operations. Specifically, it filters the cross-difference signal to control frequency response and adjusts the mixing ratio between original and expanded signals to maintain proper audio image positioning while achieving sound stage expansion.
2Area of stationary object
If cross differencing is applied to expand sound stage, then sound stage width is improved, but treble boost occurs and listeners are distracted
Solution Approach 1:
The patent converts the harmful treble boost effect into a beneficial outcome by using filtering to shape the frequency response. The cross-difference signal, which naturally produces treble boost, is filtered to control the high-frequency content, transforming the distracting artifact into a controlled enhancement that supports the sound stage expansion without causing distraction.
3Area of stationary object
If cross differencing is applied to expand sound stage, then sound stage width is improved, but center audio images are decreased in volume
Solution Approach 1:
The patent merges the original audio signal with the filtered cross-difference signal in a controlled mixing ratio. This combination allows the sound stage expansion benefits to be achieved while maintaining adequate center image volume, as the original signal components are preserved and blended with the expanded signal rather than being replaced.
Data Source
AI summary
An apparatus for effecting sound stage expansion in an audio system presenting two sound channels includes: (a) A first signal source coupled for providing at least one first signal representing a first sound channel to at least one first input locus of a first amplifying unit. The first amplifying unit participates in presenting the first sound channel. (b) A second signal source coupled for providing at least one second signal representing a second sound channel to at least one second input locus of a second amplifying unit. The second amplifying unit participates in presenting the second sound channel. (c) At least one first filter unit coupling the first signal source with at least one of the at least one second input locus. (d) At least one second filter unit coupling the second signal source with at least one of the at least one first input locus.