Active Noise Reduction Using Psychoacoustic Masking
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Solution Overview
Problem
Existing active noise reduction technologies face challenges in efficiently reducing ambient noise in frequency regions where it is not masked by audio signals, leading to potential distortion of the input signal and suboptimal noise cancellation performance.
Innovation Solution
A method and system for active noise reduction that generates a noise cancellation signal based on both the audio signal and ambient noise signals, using optimized filter parameters and psychoacoustic masking models to focus noise reduction in unmasked frequency regions, thereby improving noise cancellation efficiency without distorting the audio signal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the intensity of an input signal is increased to reduce ambient noise perception, then the noise reduction effect is improved, but the input signal becomes distorted
Solution Approach 1:
The patent applies local quality by making the noise reduction effect frequency-dependent. The system identifies frequency regions where ambient noise is not masked by the audio signal and applies noise reduction primarily in those specific frequency regions rather than uniformly across all frequencies. This selective approach reduces noise perception while preserving the quality of the audio signal in the frequency regions where masking already occurs.
2Productivity
If noise reduction is applied across all frequency regions, then the overall noise reduction efficiency is improved, but the audio signal quality deteriorates in frequency regions where noise is already masked
Solution Approach 1:
The patent applies partial action by implementing noise reduction only in the frequency regions where it is necessary - specifically where ambient noise exceeds the masking threshold of the audio signal. In frequency regions where the audio signal already masks the noise, no additional noise reduction is applied. This partial application of noise reduction maintains audio signal quality while still achieving effective noise control in the critical frequency regions.
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 effectively reduces ambient noise in unmasked frequency regions, enhancing noise cancellation performance while maintaining the quality of the audio signal, by using optimized filter parameters and psychoacoustic masking models to improve perceptual masking of residual noise.
Implementation Method 1
a loudspeaker produces a noise cancellation signal in the form of anti-noise which at least partially cancels the ambient noise
Implementation Method 2
The psychoacoustic masking effect is used to reduce or even eliminate the human perception of an auditory noise by providing a masking sound to the human user
Data Source
AI summary
A method of active noise reduction is described which comprises receiving an audio signal (132) to be played, receiving a noise signal (105, 107, 116, 118, 126), indicative of ambient noise (111), from at least one microphone (104, 106), and generating a noise cancellation signal (114) depending on both, said audio signal (132) and said noise signal (105, 107, 116, 118, 126).