Multi-Microphone Headphone Shell for Multi-Directional Noise Reduction
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Solution Overview
Problem
Existing active noise control headphones are ineffective in reducing noise from multiple directions due to limited microphone placement and directivity, leading to incomplete noise representation and reduced noise reduction performance.
Innovation Solution
The design incorporates a rigid cup-like shell with a microphone arrangement of at least three microphones regularly distributed over the outer surface, generating a second electrical signal to reduce noise through an active noise control filter, and a speaker in the cavity opening to counteract noise traveling through the shell.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single microphone is used in conventional ANC headphones, then the device complexity is low, but the noise reduction performance is insufficient for multi-directional noise
Solution Approach 1:
The single microphone is segmented into multiple microphones (at least three) distributed regularly over the outer surface of the shell. Each microphone captures noise from different directions, and the signals are processed separately before being combined to achieve comprehensive multi-directional noise reduction while maintaining manageable system complexity
Solution Approach 2:
The microphone arrangement transitions from a single-point measurement to a spatial distribution over the shell surface. By positioning microphones at multiple locations (e.g., vertices of a triangle or regular polygon), the system captures noise from multiple spatial dimensions and directions, enabling effective cancellation of noise arriving from any direction
2Reliability
If microphones are positioned to capture noise from multiple directions, then the noise cancellation effectiveness improves, but the device complexity increases
Solution Approach 1:
Multiple microphone signals captured from different directions are merged and processed together through the active noise control filter. The filter combines the individual signals to generate a unified anti-noise signal that addresses noise from all directions simultaneously, achieving comprehensive noise cancellation without requiring separate processing systems for each microphone
Solution Approach 2:
The active noise control filter is designed to handle signals from multiple microphones simultaneously, making it a universal processing unit that can manage noise from any direction. The filter's transfer characteristic is configured to process combined signals from all microphones to reduce noise traveling through the shell from any direction
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 enhances noise reduction by accurately capturing sound from multiple directions, improving noise cancellation performance by reducing noise that travels through the shell from various angles.
Implementation Method 1
a microphone arrangement configured to pick up sound at least at three positions that are regularly distributed over the outer surface, and to provide a first electrical signal that represents the picked-up sound
Implementation Method 2
a speaker disposed in the opening of the cavity and configured to generate sound from the second electrical signal
Implementation Method 3
The noise collected by the first microphone is inverted in phase and emitted from the speaker to reduce the external noise
Data Source
AI summary
Embodiments are disclosed relating to an active noise reducing system and method for a headphone with a rigid cup-like shell which has an outer surface and an inner surface that encompasses a cavity with an opening. The system and method include picking up sound at least at three positions that are regularly distributed over the outer surface, and providing a first electrical signal that represents the picked-up sound. The system and method further include: filtering the first electrical signal to provide a second electrical signal, and generating in the opening of the cavity sound from the second electrical signal. Filtering is performed with a transfer characteristic that is configured so that noise that travels through the shell from beyond the outer surface to beyond the inner surface is reduced by the sound generated in the opening.