Desktop Speakerphone Microphone Clusters Reduce Acoustic Feedback
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Solution Overview
Problem
Existing desktop speakerphones are expensive to manufacture, have limited reduction of acoustic coupling due to manufacturing tolerances and changing acoustic behavior, and offer low signal-to-noise ratio at lower frequencies, with design constraints affecting their physical appearance and performance.
Innovation Solution
A desktop speakerphone design featuring two microphone clusters with three pressure microphones each, a central sound driver, and advanced signal processing including high-frequency array processors, residual-echo cancellers, and adaptive filter control to reduce acoustic feedback and enhance sound quality, while being cost-effective and versatile in design.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If gradient microphones are used to reduce acoustic coupling, then acoustic feedback is reduced, but manufacturing cost increases and signal-to-noise ratio decreases at lower frequencies
Solution Approach 1:
The patent divides the microphone system into multiple pressure microphones arranged in clusters rather than using a single gradient microphone. This segmentation allows the system to achieve directional characteristics through spatial arrangement and signal processing while using simpler, less expensive pressure microphones that do not have the manufacturing cost and performance limitations of gradient microphones.
Solution Approach 2:
The patent introduces signal processing circuitry as an intermediary between the microphones and the acoustic feedback path. By using electronic signal processing including adaptive filtering and beamforming, the system can reduce acoustic coupling effects without relying on the complex acoustic field manipulation required by gradient microphones, thereby reducing manufacturing cost while maintaining effectiveness.
2Object-affected harmful factors
If gradient microphones are used to reduce acoustic coupling, then acoustic feedback is reduced, but signal-to-noise ratio at lower frequencies decreases
Solution Approach 1:
The patent uses multiple pressure microphones segmented into clusters rather than single gradient microphones. This arrangement allows the system to maintain good low-frequency response characteristics while achieving directional selectivity through spatial processing, thereby improving signal-to-noise ratio at lower frequencies compared to gradient microphones.
Solution Approach 2:
The patent implements adaptive feedback cancellation using signal processing that continuously monitors and compensates for acoustic feedback paths. This feedback mechanism allows the system to maintain low signal-to-noise ratios at lower frequencies by electronically canceling feedback without relying on the acoustic null patterns of gradient microphones that degrade at low frequencies.
3Object-affected harmful factors
If multiple gradient microphones are arranged to achieve directional characteristics, then acoustic coupling is reduced, but device complexity increases
Solution Approach 1:
The patent segments the microphone system into clusters of pressure microphones with defined spatial relationships. This segmentation simplifies the physical arrangement compared to gradient microphones while maintaining directional characteristics through the clustered configuration and associated signal processing.
Solution Approach 2:
The patent replaces the mechanical/acoustic complexity of gradient microphone construction with a simpler pressure microphone arrangement combined with electronic signal processing. By substituting mechanical gradient formation with electronic beamforming and spatial filtering, the system reduces device complexity while achieving similar acoustic coupling reduction.
4Object-affected harmful factors
If the teleconferencing unit shape is optimized for directional microphone performance, then acoustic coupling is reduced, but design flexibility and physical appearance constraints increase
Solution Approach 1:
The patent replaces shape-dependent acoustic solutions with electronic signal processing solutions. By using adaptive beamforming and digital signal processing, the system achieves acoustic coupling reduction without being constrained by specific physical shapes, thereby providing design flexibility and versatility in physical appearance.
Solution Approach 2:
The patent implements dynamic, adaptive signal processing that can adjust to different acoustic environments and configurations. This dynamic approach allows the system to maintain effective acoustic coupling reduction across various shapes and orientations, providing design flexibility that static shape optimization cannot achieve.
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 provides a cost-effective, high-quality sound experience with reduced acoustic feedback and design flexibility, improving signal-to-noise ratio across frequencies and maintaining effective directional microphone performance.
Implementation Method 1
an upwardly directed sound driver (5) mounted centrally at the upper side of the housing (2), so that the sound driver (5) can emit speaker sound (Ae) to multiple users
Implementation Method 2
two microphone clusters (6, 7), each comprising three pressure microphones (10, 11, 12), so that each microphone cluster (6, 7) can receive voice sound (Av) from one or more of the users
Implementation Method 3
an acoustic feedback reduction processor (57) that reduces acoustic feedback in the microphone signals (Am) in dependence on the speaker sound (Ae)
Data Source
AI summary
The present invention relates to a desktop speakerphone constructed to make the desktop speakerphone less space-consuming while having improved audio qualities. The desktop speakerphone preferably has two microphone clusters 6, 7 mounted at the upper side of the housing 2 closer towards respective longitudinal ends 8 of the latter, so that each microphone cluster 6, 7 can receive voice sound Av from one or more of the users. Each microphone cluster 6, 7 preferably comprises three pressure microphones 10, 11, 12. Furthermore, within each microphone cluster 6, 7, the second and third sound inlets 14, 15 are preferably arranged symmetrically on opposite sides of the respective median plane 18. Within each microphone cluster 6, 7, the relative arrangement of the three sound inlets 13, 14, 15 defines a respective microphone axis 9, 19 for each of the microphone pairs 10, 11, 10, 12. The microphone axis 9 of the first microphone pair 10, 11 extends through the first and the second sound inlet 13, 14, while the microphone axis 19 of the second microphone pair 10, 12 extends through the first and the third sound inlet 13, 15. The microphones are connected to multiple array processors, each configured to provide an array signal in dependence on two or more of the multiple microphone signals. First and second array processor configured to provide array signals in dependence on microphone signals.