Headphone Noise Compensation Using Adaptive Transfer Functions
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Solution Overview
Problem
Existing headphone technologies face limitations in effectively combining active noise cancellation and noise compensation, particularly in enhancing audio quality by addressing high-frequency noise and varying environmental conditions, with current methods being constrained by hardware limitations and non-linear dependencies on external noise and audio signal features.
Innovation Solution
An audio processing device with a selector and noise compensation unit that selects transfer functions based on features of external noise and content audio signals to compute gains for noise compensation, transforming noise and audio signals to simulate their arrival at the listener's eardrum, thereby improving perceived audio quality by distinguishing between different signal levels and directivities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If active noise cancellation is used to reduce external noise, then noise level at eardrum is reduced, but high-frequency noise cancellation is limited due to hardware constraints
Solution Approach 1:
The patent combines active noise cancellation with perceptual noise compensation to create a hybrid system. The active noise cancellation unit handles low-frequency noise while the perceptual noise compensation unit addresses high-frequency noise, merging both approaches to overcome the hardware limitations of active cancellation alone.
Solution Approach 2:
The noise processing function is segmented into two distinct units: active noise cancellation for low-frequency components and perceptual noise compensation for high-frequency components. This segmentation allows each unit to specialize in its optimal frequency range, with the combiner integrating both outputs.
2Object-affected harmful factors
If noise compensation boosts audio signal in noisy spectral regions, then perceived audio quality is improved, but audio signal modification increases complexity
Solution Approach 1:
The perceptual noise compensation applies different processing gains to different spectral regions based on local noise characteristics. The noise compensation unit calculates separate gains for each frequency band, allowing targeted enhancement only where needed rather than uniformly boosting the entire audio signal.
3Object-affected harmful factors
If combined active noise cancellation and noise compensation are implemented, then both noise reduction and audio quality enhancement are achieved, but system complexity increases
Solution Approach 1:
The combiner unit serves multiple functions: it combines the outputs of active noise cancellation and perceptual noise compensation, applies overall gain adjustment, and handles the final audio signal routing. This multi-functionality reduces the need for separate dedicated components for each processing stage.
Data Source
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AI summary
The disclosure relates to combined active noise cancellation and noise compensation in a headphone. An audio processing device includes a selector and a noise compensation unit. The selector can select one of a plurality of first transfer functions based on at least one feature of at least one of an external noise and a content audio signal representing a sound to be reproduced through the headphone. The noise compensation unit can compute a second audio signal by applying the selected first transfer function to a first audio signal, and derive gains for the noise compensation at least based on the second audio signal. The at least one feature can be used to distinguish at least two of the first transfer functions. Each of the first transfer functions can transform the first audio signal to the second audio signal which is assumed as representing a version of the sound represented by the first audio signal, which arrives at an eardrum of a listener wearing the headphone. The first audio signal is one of a noise signal representing the external noise and the content audio signal.