Hands-Free Voice Apparatus DSP Echo Cancellation
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Solution Overview
Problem
Hands-free voice communication devices face issues with echo and acoustic instability due to the close proximity of loudspeakers and microphones, leading to annoying reflections and howling.
Innovation Solution
A hands-free voice communication apparatus with a speakerphone and earpiece combo, incorporating a digital signal processing (DSP) module that uses multiple microphones and a communication module to perform digital signal processing based on different parameters for speakerphone and earpiece modes, along with an anti-vibration design for microphones to reduce echo and improve sound quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the loudspeaker and microphones are placed in close proximity to achieve a compact hands-free device, then the device size is reduced and portability is improved, but echo and acoustic instability occur due to sound reflections between the loudspeaker and microphones
Solution Approach 1:
The patent uses the harmful acoustic reflections and echo paths as useful information by placing reference microphones near the loudspeaker to capture these reflections. These captured reflections are then used by the DSP to generate canceling signals that actively neutralize the echo, converting the harmful acoustic interference into a beneficial feedback mechanism for echo cancellation.
Solution Approach 2:
The patent implements an active feedback mechanism where reference microphones capture acoustic reflections from the loudspeaker, and the DSP module processes these signals to generate canceling signals that are fed back to the system. This closed-loop feedback system continuously monitors and compensates for acoustic instability and echo in real-time.
2Reliability
If multiple microphones are added to improve voice pickup and echo cancellation capability, then communication quality is improved, but device complexity and manufacturing cost increase
Solution Approach 1:
The patent segments the microphone functionality into distinct roles: main microphones for voice pickup and reference microphones for capturing acoustic reflections. This segmentation allows each microphone type to be optimized for its specific function and enables the DSP to process signals from different microphone groups separately, managing complexity through functional division.
Solution Approach 2:
The reference microphones serve multiple functions: they capture acoustic reflections for echo cancellation, provide feedback for acoustic stability monitoring, and enable the DSP to adapt to different acoustic environments. This multi-functionality reduces the need for additional dedicated components.
3Ease of operation
If the hands-free device operates in speakerphone mode with high loudspeaker volume, then convenience and hands-free operation are improved, but acoustic shock and howling occur due to microphone pickup of loudspeaker reflections
Solution Approach 1:
The patent captures the harmful loudspeaker reflections using reference microphones positioned near the loudspeaker. These captured reflections are then processed by the DSP to generate active canceling signals that neutralize the acoustic shock and howling, converting the harmful high-volume reflections into an opportunity for precise echo cancellation.
Solution Approach 2:
The reference microphones act as intermediaries between the loudspeaker and the main microphones, capturing the acoustic reflections before they reach the main microphones. The DSP uses these intermediary-captured signals to generate canceling signals that prevent the harmful reflections from causing acoustic shock or howling.
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 effectively reduces echo and enhances sound quality in both speakerphone and earpiece modes, providing reliable and convenient hands-free communication by using directional and omni-directional microphones with DSP processing to manage loudspeaker volume and pickup patterns.
Implementation Method 1
The loudspeaker provides an acoustic output
Implementation Method 2
Each microphone receives acoustic input and provides an input signal
Implementation Method 3
The DSP module performs digital signal processing on the input signals from the microphones and provides an output signal for the loudspeaker
Data Source
AI summary
A hands-free voice communication apparatus includes a speakerphone and earpiece combo, a digital signal processing (DSP) module, and a communication module. The hands-free apparatus may be used as a speakerphone or an earpiece. The speakerphone and earpiece combo includes a loudspeaker and one or multiple microphones. The loudspeaker provides an acoustic output. Each microphone receives an acoustic input and provides an input signal. The DSP module performs digital signal processing on the input signals from the microphones and provides an output signal for the loudspeaker. The DSP module may perform digital signal processing with different sets of parameters for the speakerphone and earpiece modes. The communication module provides communication between the hands-free apparatus and a communication device, e.g., a cellular phone or a wireless PDA.