Stereo Signal Rendering with Adaptive Dipole Delay
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Solution Overview
Problem
Portable devices with closely spaced loudspeakers, such as smartphones and tablets, struggle to provide an immersive stereo experience due to the proximity of the speakers, resulting in a narrow, 'mono-like' sound reproduction, and existing methods require the listener to be centrally positioned to achieve optimal sound quality.
Innovation Solution
A method that adjusts the rendering of difference and spatial signals based on the listener's position by adapting the delay of dipole signals according to the desired direction, allowing for improved sound steering and spatial perception without the need for central positioning, using conventional loudspeakers and employing techniques like Short-Time Fourier Transform and Quadrature Mirror Filter for signal processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the two loudspeakers are placed close together to fit in a portable device, then the device size is reduced, but the stereo spatial effect deteriorates and sound reproduction becomes narrow and mono-like
Solution Approach 1:
The patent applies parameter changes by modifying the time delay parameter of the difference signal based on the listener's position. By dynamically adjusting the delay parameter τ in the signal processing equations, the system compensates for the fixed physical distance between loudspeakers, creating variable spatial effects that maintain immersion regardless of speaker proximity
Solution Approach 2:
The system introduces dynamics by making the time delay parameter adaptive rather than fixed. The delay parameter changes dynamically based on detected listener position, transforming a static speaker arrangement into a dynamic audio field that responds to user movement, thereby maintaining stereo spatial effect despite fixed close speaker placement
2Ease of manufacture
If dipole rendering is used to enhance spatial effect, then spatial perception is improved, but the listener must be positioned centrally to achieve optimal sound quality
Solution Approach 1:
The system implements feedback by detecting the listener's position and using this information to adjust the time delay parameter of the difference signal. This closed-loop approach allows the audio system to adapt to the listener's location, maintaining optimal spatial effect without requiring precise central positioning
Solution Approach 2:
The system performs preliminary action by pre-calculating and applying the appropriate time delay adjustment based on detected listener position before the listener even perceives the sound change. This proactive adjustment ensures optimal spatial effect is maintained continuously as the listener moves
Data Source
AI summary
The invention relates to a method for rendering a stereo audio signal over a first loudspeaker and a second loudspeaker with respect to a desired direction, the stereo audio signal comprising a first audio signal component (L) and a second audio signal component (R), the method comprising: providing a first rendering signal based on a combination of L and a first difference signal obtained based on a difference between L and R to the first loudspeaker, and providing a second rendering signal based on a combination of R and a second difference signal obtained based on the difference between L and R to the second loudspeaker, such that both difference signals are different with respect to sign and one difference signal is delayed by a delay compared to the other difference signal to define a dipole signal, wherein the delay is adapted according to the desired direction.