In-Ear Echo Suppression via Adaptive LMS Filtering
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Solution Overview
Problem
Earpieces often suffer from echo feedback issues due to inadequate sealing, leading to annoying 'howling' sounds that degrade voice communication and listening experiences, especially when ambient sounds leak into the ear canal.
Innovation Solution
A method and device for in-ear canal echo suppression using Ambient Sound Microphones and Ear Canal Microphones, which capture and process signals to suppress echoes by adjusting gain levels and filtering based on background noise and voice activity, employing a Least Mean Squares filter to model the inner ear-canal microphone transfer function and adapt filter coefficients accordingly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the earpiece is not properly sealed within the ear canal, then ambient sounds can leak through into the ear canal, but this creates an echo feedback condition that generates annoying howling sound
Solution Approach 1:
The system uses the ear canal microphone to detect echo feedback and implements active echo suppression by processing the ambient sound microphone signal to cancel the feedback path. The feedback loop is monitored and compensated for digitally to eliminate the howling sound while maintaining the open earpiece design.
Solution Approach 2:
The patent introduces digital signal processing as an intermediary between the ambient sound microphone and the ear canal receiver. The processor analyzes signals from both microphones and applies filtering and echo cancellation algorithms to mediate the feedback path, allowing the earpiece to remain unsealed while preventing echo feedback.
2Reliability
If the earpiece provides sufficient occlusion, then the user's voice can be enhanced using both ambient sound microphone and ear canal microphone, but this isolates the user from ambient sounds
Solution Approach 1:
The system dynamically adjusts the mixing ratio between ambient sound microphone signal and ear canal microphone signal based on detected voice activity and ambient noise levels. During voice communication, the ear canal microphone signal is emphasized for reliable voice enhancement, while ambient sounds are selectively permitted through the processor to maintain awareness of the environment.
Solution Approach 2:
The patent changes the acoustic parameters by using digital signal processing to selectively filter and mix frequencies from both microphones. The processor adjusts gain levels and applies frequency-dependent filtering to enhance voice frequencies from the ear canal microphone while allowing certain ambient frequencies to pass, thereby maintaining both voice enhancement and ambient sound awareness.
3Adaptability or versatility
If the ear canal receiver loops back sound from the ambient sound microphone, then the user can listen to captured sound, but this creates a feedback loop that generates echo
Solution Approach 1:
The system uses feedback principles constructively by implementing an adaptive filter that models the feedback path from the ear canal receiver to the ear canal microphone. The processor continuously updates the filter coefficients to match the actual acoustic feedback path, then uses this model to predict and subtract the echo from the loopback signal, enabling clear sound monitoring without feedback.
Solution Approach 2:
The patent replaces the purely acoustic feedback loop with a digital signal processing system. Instead of relying on acoustic isolation alone, the system uses electronic signal processing to identify, model, and cancel the feedback path. The processor substitutes digital echo cancellation for mechanical acoustic sealing, allowing the earpiece to maintain an open design while preventing feedback.
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
Effectively reduces echo feedback, enhancing voice communication quality and listening experiences by isolating ambient noise and amplifying the user's voice, while maintaining safe sound reproduction levels and ensuring proper acoustic sealing.
Implementation Method 1
A method and device for in-ear canal echo suppression using Ambient Sound Microphones and Ear Canal Microphones, which capture and process signals to suppress echoes by adjusting gain levels and filtering based on background noise and voice activity
Implementation Method 2
employing a Least Mean Squares filter to model the inner ear-canal microphone transfer function and adapt filter coefficients accordingly
Implementation Method 3
capturing an ambient acoustic signal from at least one Ambient Sound Microphone (ASM) to produce an electronic ambient signal
Implementation Method 4
capturing in an ear canal an internal sound from at least one Ear Canal Microphone (ECM) to produce an electronic internal signal
Implementation Method 5
delivering audio content to an ear canal by way of an Ear Canal Receiver (ECR) to produce an acoustic audio content
Data Source
AI summary
An earpiece (100) and acoustic management module (300) for in-ear canal echo suppression control suitable is provided. The earpiece can include an Ambient Sound Microphone (111) to capture ambient sound, an Ear Canal Receiver (125) to deliver audio content to an ear canal, an Ear Canal Microphone (123) configured to capture internal sound, and a processor (121) to generate a voice activity level (622) and suppress an echo of spoken voice in the electronic internal signal, and mix an electronic ambient signal with an electronic internal signal in a ratio dependent on the voice activity level and a background noise level to produce a mixed signal (323) that is delivered to the ear canal (131).