Stereo Signal Delay Filtering for Headphone Spatial Fidelity
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Solution Overview
Problem
Existing audio technologies fail to accurately replicate the stereo acoustic experience of multiple speakers in an anechoic room using headphones, due to differences in sound propagation and attenuation caused by ear spacing and head geometry, leading to fidelity issues and bass deficiencies.
Innovation Solution
A processing system that simulates the stereo acoustic experience by adjusting delay times and frequencies based on ear spacing and speaker inclination angles, using adjustable delay blocks, low-pass filters, and active filters to enhance and attenuate signals, ensuring fidelity across various frequencies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If delay blocks with frequency-dependent delay are used to simulate sound propagation, then the phase of the signal is maintained constant, but the fidelity of sound reproduction deteriorates at high frequencies above 4 kHz
Solution Approach 1:
The patent applies parameter changes by using frequency-dependent delay blocks where the delay time varies with frequency. Specifically, the delay is set to be larger for lower frequencies and smaller for higher frequencies, matching the natural sound propagation characteristics. This resolves the contradiction by allowing phase stability across the audio spectrum while maintaining sound reproduction fidelity through accurate frequency-specific delay simulation.
2Device complexity
If fixed delay values (50-2000 μs) are used in delay blocks, then the device complexity is reduced, but the ability to accurately simulate speaker inclination angles is lost
Solution Approach 1:
The patent applies dynamics by making the delay values adjustable rather than fixed. The delay blocks are configured with variable delay times that can be adjusted based on the desired speaker inclination angles and listener position. This allows the system to accurately simulate different spatial configurations while maintaining manageable device complexity through software-based adjustment rather than hardware complexity.
Solution Approach 2:
The patent uses parameter changes by allowing the delay time parameter to vary based on acoustic geometry calculations. The delay values are dynamically determined from the inclination angles of virtual speakers and the distance between earpieces, enabling precise simulation of sound propagation paths without requiring complex fixed hardware configurations.
3Adaptability or versatility
If the distance between earpieces is assumed to be 68 cm for maximum delay simulation, then the delay range is extended, but the anatomical accuracy deteriorates since actual earpiece distances are 15-18 cm
Solution Approach 1:
The patent applies parameter changes by calculating delay values based on the actual anatomical distance between earpieces (15-18 cm) rather than using fixed unrealistic values. The delay time is computed from the actual distance and the desired virtual speaker inclination angle, ensuring anatomical accuracy while maintaining the full range of audible delay simulations through mathematical modeling.
Data Source
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AI summary
System (100) for processing a stereo acoustic signal comprising: a first input (I1) and a second input (I2), a first output (U1) and a second output (U2), a first summing block (S1) connected to the first input (I1) and to the first output (U1), a second summing block (S2) connected to the second input (I2) and to the second output (U2), a first delay block (D1) connected to the first input (I1) and to the second summing block (S2), and a second delay block (D2) connected to the second input (I2) and to the first summing block (S1).