In-Ear Communication Equipment Phase Cancellation Echo
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Solution Overview
Problem
Existing communication devices with in-ear sound pickup face challenges in achieving full-duplex communication due to issues with echo cancellation, complexity, and incompatibility with hearing protection, particularly at low frequencies, leading to cumbersome half-duplex communication and unintentional sound transmission.
Innovation Solution
A communication equipment system with in-ear devices configured to deliver voice signals out of phase to the right and left ears, using summing units and phase shifters to eliminate echo, while incorporating ambient sound reproduction and adaptive gain modules to manage sound levels, ensuring full-duplex communication and hearing protection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If conventional echo cancellation algorithms are used with in-ear microphones, then echo cancellation may be achieved, but the algorithms cannot be applied effectively because the microphone is very close to the speaker
Solution Approach 1:
Instead of using conventional echo cancellation algorithms that attempt to subtract the echo signal, the patent inverts the approach by playing back the outgoing voice signal in opposite phase through the loudspeaker. This anti-phase signal directly counteracts the echo at the microphone, eliminating the need for complex cancellation algorithms and achieving effective echo removal despite the close proximity of the microphone to the speaker.
Solution Approach 2:
The patent changes the phase parameter of the outgoing voice signal before playback, specifically shifting it by 180 degrees (opposite phase). This parameter change transforms the echo from a harmful positive signal into a canceling negative signal, allowing the system to effectively eliminate echo without requiring complex algorithms adapted to the close microphone-speaker configuration.
2Ease of operation
If a PTT button is used for half-duplex communication, then the user's voice can be captured, but communication becomes cumbersome and the user cannot speak and listen simultaneously
Solution Approach 1:
The patent enables continuous full-duplex communication where the user can speak and listen simultaneously without interruption. The system continuously captures the user's voice through the in-ear microphone, processes it with echo cancellation, and transmits it while also continuously playing back the remote party's voice through the loudspeaker, eliminating the need for PTT button operations and enabling seamless two-way communication.
Solution Approach 2:
The patent introduces an intermediary echo cancellation mechanism that mediates between the user's speech and the incoming audio stream. This intermediary process actively removes the echo of the user's own voice from the incoming audio, allowing the user to clearly hear the remote party while speaking, thus enabling simultaneous speak and listen functionality without PTT control.
3Ease of operation
If speech detector is used to automatically stop transmission when user speaks, then PTT button is eliminated, but transmission may be unintentionally stopped when user speaks directly to someone nearby
Solution Approach 1:
The patent introduces an intermediary echo cancellation mechanism that actively removes the echo of the user's own voice from the incoming audio stream. This intermediary process mediates between the speech detector and the transmission control, preventing unintentional transmission stops by distinguishing between direct speech (which should not trigger automatic stop) and echoed speech (which should trigger automatic stop), thereby maintaining reliable transmission control with automatic operation.
4Object-affected harmful factors
If in-ear hearing protection is provided, then user is protected from ambient sound, but user becomes isolated from surrounding environment
Solution Approach 1:
The patent enables continuous playback of ambient sound through the loudspeaker while maintaining hearing protection. The system continuously captures ambient sound through the in-ear microphone, processes it, and plays it back to the user in real-time, allowing the user to remain protected from potentially harmful ambient noise while staying aware of and able to respond to important environmental sounds.
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
Enables full-duplex communication by effectively eliminating echo and ambient sound interference, allowing users to speak and listen simultaneously without pressing a button, while maintaining safe sound levels and natural speech quality.
Implementation Method 1
a first voice signal is delivered to the loudspeaker of the first device and a second voice signal is delivered to the loudspeaker of the second device, the first and second voice signals being based on at least one source voice signal such that the first voice signal and the second voice signal are in opposite phase, i.e. out of phase by Pi
Data Source
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AI summary
The present invention relates to communication equipment (1) comprising a first device (2) and a second device (3), each comprising a first microphone (22, 32) and a loudspeaker (21, 31), the communication equipment (1) being configured such that a first speech signal (-p) supplied to the loudspeaker (21) and a second speech signal (p) supplied to the loudspeaker (31) are in phase opposition, each microphone being configured to pick up at least one voice (s) of the user and a sound from the loudspeaker (21, 31), the communication equipment (1) further comprising a first summer (4) configured to receive as input and to sum the output signal (x1) corresponding to the first device (2) and the output signal (x2) corresponding to the second device (3), the first summer (4) outputting the total output signal (x) equal to the sum of the output signal (x1) corresponding to the first device (2) and the output signal (x2) corresponding to the second device (3), and the total output signal (x) comprising a component of the voice (s) of the user and being free of a component of the at least one source speech signal (p0, -p0).