Selective Noise Cancellation Headphones Using Phase-Shifted Signal Processing

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Solution Overview

Problem

Existing noise-cancelling technologies fail to selectively reduce ambient noise while allowing important sounds to pass through, leading to discomfort and safety issues for workers and passengers in noisy environments.

Innovation Solution

A novel noise-cancelling system that classifies incoming signals using predetermined models, identifies unwanted noise classes, and generates phase-shifted signals to cancel selected noise while allowing other sounds to remain unattenuated.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If standard ear-protection devices are worn to block ambient noise, then noise protection is improved, but all sounds including important sounds are muffled

Engineering Contradiction:

Improvenoise protectionVSAvoidsound attenuation

Core Design Contradiction:

Object-affected harmful factorsVSLoss of information

Solution Approach 1:

The patent applies local quality by treating different frequency ranges and sound types differently. The system analyzes incoming audio signals and applies noise cancellation selectively to identified noise frequencies while preserving other frequencies. This allows the headphones to provide noise protection for harmful sounds while maintaining audibility of important sounds through differential frequency processing.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The system dynamically changes audio parameters by adjusting the attenuation level for different frequency bands in real-time. Based on environmental noise analysis, the system modifies gain parameters selectively - applying stronger attenuation to noise frequencies and minimal or no attenuation to important sound frequencies, thereby resolving the contradiction between noise blocking and sound preservation.

Inventive Principle:

Principle #35Parameter changes

2Loss of information

If users raise the volume to overcome environmental noise, then sound clarity is improved, but hearing damage risk increases

Engineering Contradiction:

Improvesound clarityVSAvoidhearing damage risk

Core Design Contradiction:

Loss of informationVSObject-affected harmful factors

Solution Approach 1:

The patent converts the harmful effect of environmental noise into a beneficial selective filtering mechanism. By analyzing the noise spectrum and identifying noise patterns, the system generates anti-phase signals that cancel noise frequencies while preserving important sounds. This allows users to maintain lower volume levels while achieving clear sound transmission, thereby reducing hearing damage risk while preserving sound clarity.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

3Loss of information

If standard earphones are used in noisy environments, then sound transmission is achieved, but user comfort and safety are compromised

Engineering Contradiction:

Improvesound transmissionVSAvoiduser comfort and safety

Core Design Contradiction:

Loss of informationVSEase of operation

Solution Approach 1:

The system dynamically adapts to changing environmental conditions by continuously analyzing incoming audio signals and adjusting noise cancellation parameters in real-time. The noise profile detection and classification systems update filtering parameters dynamically, allowing the headphones to maintain optimal performance across varying noise environments while preserving user comfort and safety through adaptive sound management.

Inventive Principle:

Principle #15Dynamics

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 system effectively reduces ambient noise while preserving important sounds, enhancing user comfort and safety by allowing users to customize noise reduction based on their needs.

Implementation Method 1

multiplying a 180° phase-shifted version of a frequency signal associated with the identified noise class by the associated frequency spectrum of the plurality of spectra

Methodology Applied

Scientific EffectPhase shift:

Data Source

PatentUS12293751B2Interactive noise cancelling headphone

Publication Date: 2025.05.06 PURDUE RES FOUND

AI summary

A method of reducing signals associated with one or more classes of unwanted noise is disclosed which includes choosing one or more classes as noise to be cancelled while allowing the remainder of classes amongst a plurality of classes to pass through, dividing an incoming time-varying signal into a plurality of snippets having a single or a plurality of durations, transforming each snippet into an associated frequency spectrum, thus generating a plurality of spectra, for each spectrum of the plurality of spectra, identifying presence of the one or more classes chosen as noise, for each identified class of noise, multiplying a 180° phase-shifted version of a frequency signal associated with the identified class of noise by a frequency spectrum of the incoming signal, thereby generating an associated frequency-domain noise-cancelled spectrum, inverse transforming the frequency-domain noise-cancelled spectrum into a time-varying noise-cancelled signal, and outputting the time-varying noise-cancelled signal.