Bandwidth Extension via Nonlinear Function for Speech Quality
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Solution Overview
Problem
Current telecommunication systems degrade speech quality due to band limiting filters, which attenuate frequency components between 50 Hz and 6000 Hz, leading to delayed and complex signal processing requirements for bandwidth extension methods.
Innovation Solution
A system that applies a non-linear function to generate and add attenuated lower frequency components to bandwidth limited audio signals, eliminating the need for spectral envelope calculation, thus reducing processing requirements and minimizing delay.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If bandwidth extension methods are used to increase speech quality by establishing speech signal components above 3400 Hz and below 300 Hz, then speech quality is improved, but processing complexity and memory requirements increase
Solution Approach 1:
The patent extracts only the essential information needed for bandwidth extension (spectral envelope characteristics and excitation signal) from the original speech signal, rather than processing the entire signal. This selective extraction reduces processing complexity while maintaining speech quality improvement.
Solution Approach 2:
The patent creates a simplified copy of the speech signal's spectral envelope characteristics and uses this copy to generate the extended bandwidth components. This copying approach avoids complex direct synthesis while preserving the essential speech characteristics.
2Manufacturing precision
If spectral envelope determination and excitation signal generation are performed to extend bandwidth, then speech quality is improved, but signal delay increases
Solution Approach 1:
The patent performs preliminary determination of the spectral envelope characteristics from the available bandwidth-limited signal before generating the extended components. This preliminary action allows the system to prepare the necessary parameters in advance, reducing the processing delay during actual bandwidth extension.
3Object-affected harmful factors
If band pass filters are applied to reduce crosstalk between channels, then channel interference is reduced, but speech quality deteriorates due to attenuation of frequency components
Solution Approach 1:
The patent converts the harmful effect of band limiting (attenuation of speech components) into a beneficial process by using the limited signal to determine spectral envelope characteristics, which are then used to regenerate the attenuated frequency components. The band limiting filter's output becomes the input for the envelope determination process.
4Manufacturing precision
If codebook pairs and neuronal networks are utilized for bandwidth extension, then speech quality is improved, but memory requirements increase
Solution Approach 1:
The patent replaces complex, memory-intensive structures (codebook pairs and neuronal networks) with a simpler, more efficient approach based on spectral envelope determination. This simpler method achieves comparable speech quality improvement without requiring large memory capacities.
Data Source
AI summary
A system is provided for extending the spectral bandwidth of a bandwidth limited audio signal by applying a nonlinear function to the bandwidth limited speech signal to generate the low frequency audio signal components that were attenuated in the bandwidth limited audio signal.