Single-Microphone Acoustic Processing for Wideband Noise Cancellation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing noise cancellation systems for headphones and earphones often require multiple microphones and increase in device size and cost to achieve effective noise reduction across an extended frequency band.
Innovation Solution
A noise reduction device using a combination of Classical Control Theory (CCT) and Internal Model Control (IMC) methods, employing a single microphone to achieve noise cancellation effects equivalent to twin-type systems, by integrating feedback-based and feedforward-based noise cancellation processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple microphones are used to achieve effective noise reduction across an extended frequency band, then noise cancellation performance is improved, but device size and cost increase
Solution Approach 1:
The patent combines feedback-based noise cancellation (using a microphone inside the casing) and feedforward-based noise cancellation (using a microphone outside the casing) into a single integrated system. This merging of two different noise cancellation approaches allows the system to achieve extended frequency band noise reduction that would otherwise require multiple separate systems or additional microphones, thereby improving noise cancellation performance without proportionally increasing device complexity
Solution Approach 2:
The noise cancellation device is designed to perform multiple functions: it simultaneously provides feedback-based cancellation for internal noise and feedforward-based cancellation for external noise across different frequency bands. This multi-functionality allows a single device to replace what would traditionally require multiple specialized microphones or systems, achieving comprehensive noise reduction while maintaining compact size and reasonable cost
2Reliability
If twin-type ambient noise cancellation device with feedback and feedforward techniques is integrated, then wide band noise cancellation is achieved, but device complexity increases
Solution Approach 1:
The patent integrates feedback-based noise cancellation (using a microphone inside the casing) and feedforward-based noise cancellation (using a microphone outside the casing) into a single unified system. This merging allows the device to achieve wide band noise cancellation across extended frequency ranges while managing complexity through integrated signal processing that coordinates both cancellation paths
Data Source
Figure 1
Figure 2
Figure 3
AI summary
[Object] To provide a sound processing device capable of effectively reducing ambient noise at low cost. [Solution] Provided is a sound processing device including: a first sound collector configured to collect a first noise signal from a noise source of noise leaking into a casing mounted to a user's ear; a first signal processing unit configured to form a first noise reduction signal used to reduce noise at a cancellation point on the basis of the first noise signal; a second signal processing unit configured to form a second noise reduction signal used to reduce noise at a cancellation point with respect to a first pseudo noise signal; an adder configured to add the first noise reduction signal and the second noise reduction signal; and a sound emitter configured to emit an output of the adder into the casing as sound. The first pseudo noise signal is a signal obtained by subtracting an output of the adder applied with a simulation transfer characteristic from an output of the first sound collector, the simulation transfer characteristic being obtained by simulating a transfer characteristic from the sound emitter to the first sound collector.