Earphone Signal Processing Circuit for Noise Reduction
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Solution Overview
Problem
Existing earphone technologies face challenges in improving speech recognition due to environmental noise interference, as current methods either fail to effectively eliminate noise or compromise tone quality when using accelerometer signals for noise reduction.
Innovation Solution
An earphone design incorporating a processing circuit and filtering module that utilizes a combination of high-pass, low-pass, and band-pass filters to process both microphone and bone-conduction audio signals, performing noise reduction and signal synthesis to enhance speech signal quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If bone-conduction audio signal is used to replace low-frequency microphone signal for noise reduction, then low-frequency noise is filtered, but the speech signal becomes muffled and blurred with worse tone quality
Solution Approach 1:
The patent segments the speech signal into multiple frequency bands (low-frequency band, mid-frequency band, high-frequency band) and processes each band separately using different filtering strategies. The low-frequency band uses bone-conduction signal with band-pass filter to remove noise, while mid and high-frequency bands use microphone signals with high-pass and low-pass filters respectively, preserving tone quality in critical frequency ranges.
Solution Approach 2:
Different filtering operations are applied to different frequency components of the signal. The band-pass filter is applied specifically to the bone-conduction audio signal for low-frequency noise reduction, while high-pass and low-pass filters are applied to microphone signals for high-frequency and mid-frequency noise reduction respectively, ensuring each frequency range is optimally processed.
2Loss of information
If accelerometer signal is used for voice activity detection, then speech and noise signals can be distinguished, but noise components remain in the speech signal
Solution Approach 1:
The patent divides the speech signal processing into multiple frequency segments and applies different noise reduction techniques to each segment. The low-frequency segment uses bone-conduction signal with band-pass filtering, while high-frequency segments use microphone signals with high-pass filtering, achieving both speech-noise distinction and noise elimination.
Solution Approach 2:
The patent introduces bone-conduction audio signal as an intermediary to obtain clean low-frequency speech components free from environmental noise. This intermediary signal is then combined with microphone signals to reconstruct the full-frequency speech signal with reduced noise across all frequency bands.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution provides an output speech signal with improved tone quality, effectively facilitating subsequent speech recognition operations by simultaneously addressing noise reduction and tone quality issues.
Implementation Method 1
there is another known technique which utilizes an accelerometer to receive a bone-conduction audio signal essentially without an environmental noise
Implementation Method 2
the high-pass filter performs a high-pass filter operation on the second speech signal to generate a first signal
Implementation Method 3
the low-pass filter performs a low-pass filter operation on the second speech signal to generate a second signal
Implementation Method 4
the band-pass filter receives a bone-conduction audio signal corresponding to the first speech signal from at least one accelerometer and performs a band-pass filter operation on the bone-conduction audio signal to generate a third signal
Data Source
AI summary
The invention provides an earphone and a set of earphones. The earphone includes a processing circuit and a filtering module. The processing circuit acquires a first speech signal and performs a pre-processing operation on the first speech signal to generate a second speech signal. The filtering module includes high-pass, low-pass, and band-pass filters. The processing circuit is further configured to: receive first, second, and third signals respectively from the high-pass, low-pass, and band-pass filters; perform a noise reduction operation on the second and third signals to generate a fourth signal; and perform a signal synthesis operation on the first and fourth signals to synthesize the first and fourth signals to form an output speech signal.