Vehicle Onboard Device Echo Noise Reduction
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Solution Overview
Problem
Onboard devices with integrated speakers and microphones in vehicles face echo noise issues due to close proximity, leading to unsatisfactory audio quality during phone calls.
Innovation Solution
The design includes a speaker, microphone, housing, and a sound guide member with specific openings and inclined surfaces to reduce echo noise by redirecting sound waves and minimizing Helmholtz resonance, while the microphone is housed in a separate case to prevent vibration transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the speaker and microphone are installed in a small space with close proximity, then the device size is reduced, but echo noise increases
Solution Approach 1:
A sound guide member is introduced as an intermediary component between the speaker and microphone. This sound guide member includes a sound guide hole with inclined surfaces that redirect sound waves from the speaker away from the microphone, preventing direct sound transmission while maintaining compact device dimensions
Solution Approach 2:
The sound guide hole employs three-dimensional inclined surfaces arranged at specific angles to redirect sound waves in alternative spatial directions. By utilizing spatial dimensionality, the design guides sound waves away from the microphone path while keeping the overall device footprint small
2Device complexity
If the third opening of the sound guide hole is positioned close to the microphone, then the device structure is simplified, but echo signal saturation occurs
Solution Approach 1:
The sound guide hole features locally optimized inclined surfaces with specific angle configurations in different regions. The third opening is positioned and angled to redirect sound waves away from the microphone, creating localized sound control zones that prevent echo saturation while maintaining overall structural simplicity
3Ease of manufacture
If the inner wall of the sound guide hole uses flat surfaces, then manufacturing is easier, but Helmholtz resonance noise increases
Solution Approach 1:
The inner wall of the sound guide hole incorporates inclined surfaces with curved or angled geometries instead of flat surfaces. These curved surfaces disrupt standing wave formation and reduce Helmholtz resonance effects, while the inclination angles are designed to maintain manufacturability through standard forming processes
4Productivity
If the speaker and microphone are mounted close together, then installation steps are reduced, but vibration transmission from speaker to microphone increases
Solution Approach 1:
The device is segmented into distinct functional modules: the speaker is mounted on the housing, while the microphone is housed in a separate first microphone case. This segmentation physically isolates the two components, preventing vibration transmission while maintaining compact overall dimensions and simple installation
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
This configuration effectively reduces echo noise and improves audio quality by minimizing echo signals and suppressing Helmholtz resonance, ensuring clear voice transmission in onboard devices.
Implementation Method 1
At least a part of an inner wall of the sound guide hole is configured by combining a plurality of inclined surfaces having different directions. Accordingly, an orientation of a sound from the speaker can be changed smoothly.
Implementation Method 2
At least a part of an inner wall of the sound guide hole is configured by combining a plurality of inclined surfaces having different directions. Accordingly, an orientation of a sound from the speaker can be changed smoothly. This allows reducing noise due to Helmholtz resonance.
Data Source
Figure 1
Figure 2(A)~2(F)
Figure 3(A)~3(B)
AI summary
A small-sized onboard device that includes a speaker and a microphone and is configured to reduce noise caused by an echo is provided. The speaker is provided inside a housing that forms a cavity inside so that a sound emission surface of the speaker faces a direction substantially orthogonal to a front surface, and a first opening is formed in a front surface of the housing. A microphone case and a sound guide member are juxtaposed on the front surface of the housing. A microphone is housed inside the microphone case. The microphone case has a sound pickup hole in a front surface of the microphone case. The sound guide member has a sound guide hole that passes through the sound guide member. The first opening is provided in a vicinity of a top surface or a bottom surface of the housing. The first opening has a height smaller than a height of the housing. As viewed from the front surface, a position and a size of a second opening on the first opening side of the sound guide hole substantially matches a position and a size of the first opening. A third opening on a front surface side of the sound guide hole is provided to be biased to a side away from the microphone case. The third opening has a height higher than a height of the first opening. At least a part of an inner wall of the sound guide hole is configured by combining a plurality of inclined surfaces having different directions.