Headphone Equalization Filters for Reducing the Occlusion Effect
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Solution Overview
Problem
In-ear and earbud headphones cause an occlusion effect, amplifying low-frequency sound pressure and affecting the naturalness of sound reproduction, especially when the user speaks, due to increased acoustic impedance.
Innovation Solution
An audio processing method using an inline microphone captures the user's voice, applies mouth-to-ear transfer functions, and filters it with equalization filters based on headphone type and acoustic impedance to reduce the occlusion effect.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If in-ear or earbud headphones seal the ear canal to attenuate outside noise, then noise isolation is improved, but low-frequency sound pressure is amplified causing occlusion effect
Solution Approach 1:
The patent applies equalization filters to modify the frequency response parameters of the audio signal, specifically attenuating low-frequency components (below 200 Hz) that cause the occlusion effect while preserving higher frequencies for natural speech perception
Solution Approach 2:
The patent extracts and removes the harmful low-frequency occlusion effect components from the audio signal using equalization filters, separating the useful speech content from the harmful amplification caused by ear canal sealing
2Object-generated harmful factors
If equalization filters are applied to reduce occlusion effect, then naturalness of voice perception is improved, but processing complexity increases
Solution Approach 1:
The patent implements equalization filters with specific parameter settings (frequency cutoff at 200 Hz, specific Q-factor values) that balance the reduction of occlusion effect with computational efficiency, avoiding overly complex processing while achieving natural voice perception
Solution Approach 2:
The patent applies partial equalization by focusing only on the critical low-frequency range (below 200 Hz) that causes occlusion, rather than processing the entire frequency spectrum, thereby reducing processing complexity while maintaining effectiveness
Data Source
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AI summary
The invention relates to a method for processing an audio signal, the method comprising: processing the audio signal according to a pair of mouth to ear transfer functions, to obtain a processed audio signal; filtering the processed audio signal, using a pair of equalization filters, to obtain a filtered audio signal, wherein a parameter of the equalization filter is depends on an acoustic impedance of a headphone; and outputting the filtered audio signal to the headphone. According to this method to counteract the occlusion effect and to provide a natural perceived sound pressure.