Noise Suppression Circuit Using Dual Microphone and Reflective Interface
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Solution Overview
Problem
Existing techniques fail to effectively suppress noise from multiple sources in the same sound space where desired speech exists, as they do not provide a method to collect noise from a wide range, and existing methods for remote sound collection focus on desired speech rather than noise suppression.
Innovation Solution
A speech processing apparatus with two microphones, one positioned to capture desired speech and noise, and another positioned at a reflective surface interface to capture noise components at a different ratio, along with a noise suppression circuit to estimate and remove noise, allowing for pseudo speech reconstruction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a microphone receives noise from a wide range of sound space, then noise suppression capability is improved, but device complexity increases
Solution Approach 1:
The sound space is segmented into two distinct regions: a first sound space where desired speech exists and a second sound space where noise is collected. The first microphone is positioned in the first sound space to capture speech, while the second microphone is positioned in the second sound space to capture noise. This spatial segmentation allows each microphone to have a dedicated function, improving noise suppression capability without requiring a single complex microphone arrangement to handle all sound sources simultaneously.
Solution Approach 2:
An acoustic interface (such as a parabolic reflector or curved surface) is introduced as an intermediary element between the noise sources and the second microphone. This interface reflects and concentrates noise from a wide range of the sound space onto the second microphone, which would otherwise require the microphone to be positioned to receive noise directly from all directions. The intermediary enables wide-range noise collection while maintaining a relatively simple microphone positioning.
2Quantity of substance
If the second microphone is positioned at the focus position of a quadratic surface interface, then noise collection from wide range is improved, but manufacturing precision requirements increase
Solution Approach 1:
The patent introduces a degree of freedom in the design of the acoustic interface by allowing it to be either a perfect quadratic surface or a pseudo surface that approximately approximates a quadratic surface. This parameter change (from exact geometric shape to approximate shape) enables the system to achieve noise collection from a wide range while reducing the manufacturing precision requirements. The pseudo surface approach maintains the essential acoustic functionality without demanding high-precision manufacturing.
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 accurate noise estimation and pseudo speech reconstruction close to the desired speech, even in environments with multiple noise sources, improving speech recognition and suppression of echo and noise components.
Implementation Method 1
a second microphone that is opened to the same sound space as that of the first microphone and disposed at a focus position of an interface that is part of a boundary of the sound space and has one of a quadratic surface shape and a pseudo surface shape approximating a quadratic surface, inputs a second mixture sound including the desired speech reflected by the interface and the noise reflected by the interface
Data Source
AI summary
A speech processing apparatus acquires pseudo speech from a mixture of sound including desired speech and noise. A first microphone inputs a first mixture sound, including desired speech and noise, and outputs a first mixture signal. A second microphone opens to the sound space and is disposed at a focus position of an interface, that is part of a boundary of the sound space and has one of a quadratic surface shape and a pseudo surface shape approximating a quadratic surface, inputs a second mixture sound including the desired speech reflected by the interface and the noise reflected by the interface at a ratio different from the first mixture sound, and outputs a second mixture signal. A noise suppression circuit suppresses an estimated noise signal based on the first mixture signal and the second mixture signal and outputs a pseudo speech signal.