In-Ear Earphone Howling Suppression Across High-Frequency Bands
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Solution Overview
Problem
Existing howling suppression methods, particularly in TWS earphones, fail to effectively suppress howling in higher frequency bands, leading to hearing damage in users with hearing impairments.
Innovation Solution
A howling suppression method that determines the type of howling event, reduces the amplitude gain of the affected frequency band, and employs a combination of adaptive and nonlinear post-processing filters to process the audio signal, thereby reducing feedback signals that cause howling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If adaptive filter is used to suppress howling, then howling suppression is achieved in lower frequency bands, but howling in higher frequency bands cannot be suppressed
Solution Approach 1:
The patent segments the frequency spectrum into multiple bands (low, mid, high frequency bands) and applies different processing strategies to each band. The adaptive filter handles lower frequency bands while a spectral subtraction method is applied to higher frequency bands, enabling comprehensive howling suppression across the entire frequency spectrum.
Solution Approach 2:
The patent changes the processing parameter (filtering method) based on the frequency band. For higher frequency bands where adaptive filters are ineffective, the system switches to spectral subtraction with adjusted parameters including gain reduction and nonlinear post-processing, thereby extending suppression capability to previously unaffected frequency ranges.
2Reliability
If gain amplification is applied in missing frequency bands for hearing impairment assistance, then hearing assistance function is improved, but howling phenomenon occurs due to close microphone-speaker distance
Solution Approach 1:
The patent introduces an intermediary processing stage between the microphone input and speaker output that includes feedback path estimation and spectral subtraction. This intermediary system estimates the feedback path characteristics and actively subtracts howling components before the signal reaches the speaker, thereby eliminating the harmful howling effect while preserving the beneficial gain amplification for hearing assistance.
Solution Approach 2:
The patent implements a feedback mechanism where the system continuously monitors the audio signal for howling characteristics, estimates the feedback path, and adjusts the filtering parameters in real-time. This feedback loop enables the system to maintain hearing assistance functionality while dynamically suppressing howling that arises from the close microphone-speaker proximity.
3Reliability
If amplitude gain is reduced in the frequency band where howling occurs, then howling suppression is improved, but audio quality may be degraded
Solution Approach 1:
The patent applies partial gain reduction only to the specific frequency bands and time periods where howling is detected, rather than uniformly reducing gain across the entire spectrum. The spectral subtraction method selectively targets howling components while preserving other audio content, thereby suppressing howling effectively while minimizing impact on overall audio quality.
Solution Approach 2:
The patent replaces simple mechanical gain reduction with a more sophisticated spectral subtraction system that includes feature extraction, howling detection, and nonlinear post-processing. This substitution allows for intelligent differentiation between howling components and legitimate audio content, reducing gain only where necessary to suppress howling while preserving audio quality in other regions.
Data Source
AI summary
Disclosed is a howling suppression method, including: determining, according to an audio signal collected by a microphone, whether a howling event occurs; if a howling event occurs, determining a howling type corresponding to the howling event; if the howling type is impulse wave howling, reducing an amplitude gain of a frequency band to which the howling event belongs, and performing a filtering process on the audio signal the amplitude gain reduction of which is reduced, to obtain a target audio signal; and controlling a speaker to play the target audio signal. According to the present disclosure, howling event suppression effect can be improved, thereby reducing the damage of audio playing to the hearing of a user. Further disclosed in the present disclosure are a howling suppression apparatus, an in-ear earphone, and a storage medium, to which the howling suppression method is applied.