Speaker as Microphone for Front-Back Sound Discrimination
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Small form factor mobile devices face challenges in directional sound capture due to form factor constraints, making it difficult to achieve front-back directivity control with conventional microphone configurations, especially in applications like camcording and video calls.
Innovation Solution
The use of a speaker as a microphone, combined with an acoustic processor that processes signals to discriminate between acoustic waves from different directions, allowing for front-back discrimination by configuring the speaker as a directional microphone and mixing signals from both the speaker and conventional microphones to enhance signal-to-noise ratio.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional microphone configurations are used in small form factor mobile devices, then the device structure is simple and easy to manufacture, but front-back directivity control is difficult to achieve
Solution Approach 1:
The speaker is configured to function as a microphone by sensing acoustic waves through its membrane, allowing a single component to serve dual purposes. This eliminates the need for additional dedicated microphones while achieving the required directivity control functionality.
Solution Approach 2:
Instead of using conventional microphones for sound capture, the invention inverts the approach by using the speaker (a sound output device) for sound input. The speaker membrane's natural response to acoustic waves is exploited for directional sound capture, achieving front-back discrimination without conventional microphone arrangements.
2Measurement precision
If multiple microphones are used for directional sound capture, then front-back discrimination capability is improved, but the device form factor increases and manufacturing becomes more complex
Solution Approach 1:
The speaker serves dual functions as both a sound output device and a sound input sensor. By utilizing the speaker membrane's physical response to acoustic waves, the system achieves directional sound capture without requiring separate microphone components, thereby maintaining a compact form factor.
Solution Approach 2:
The speaker's own membrane structure is utilized for sensing acoustic waves. The membrane's natural vibration characteristics in response to incoming sound provide the necessary directional information, eliminating the need for external sensing components and reducing overall device volume.
3Measurement precision
If speaker is used as microphone, then front-back sound discrimination is enabled in compact devices, but signal processing complexity increases
Solution Approach 1:
The acoustic processor analyzes the signal induced on the speaker terminals and applies processing algorithms to discriminate between front and back acoustic sources. The system uses the speaker's inherent directional response characteristics and processes the feedback signal to achieve accurate sound direction identification.
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 approach enables improved front-back sound discrimination and noise suppression, enhancing the quality of speech and audio capture in mobile devices, particularly in camcorder and video call modes, by leveraging the directional response of the speaker membrane.
Implementation Method 1
sense a signal induced on speaker terminals in response to at least one acoustic source
Data Source
Figure 1A~1B
Figure 2~3
Figure 4~5
AI summary
An acoustic processor for a mobile device is described the mobile device comprising a speaker including a speaker membrane, the speaker membrane having a first speaker membrane side and second speaker membrane side opposite the first speaker membrane side, a mobile device housing for providing a first acoustic path between the first speaker membrane side and the exterior of the mobile device and a second acoustic path between the second speaker membrane side and the exterior of the mobile device, the acoustic processor being configured and arranged to sense a signal on an acoustic processor input, the signal being induced on at least one terminal of the speaker in response to acoustic waves process the induced signal to discriminate between acoustic waves from different directions; and output the processed signal on an acoustic processor output.