Audio Signal Reverberation Extraction and Modification
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Solution Overview
Problem
Current technologies face challenges in modifying the reverberant component of an audio signal without direct measurement of the acoustic space, affecting the appropriateness of reverberation for various applications, such as musical recordings, teleconferencing, and speech recognition, where inappropriate reverberation degrades signal clarity and intelligibility.
Innovation Solution
A method and apparatus that estimate the impulse response of the reverberant system by dividing it into blocks, deriving magnitude response estimates from the audio signal, and altering the reverberant characteristics without direct measurement, allowing for the extraction and modification of the reverberant component to match desired acoustic characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If artificial reverberation devices are used to add reverberant energy, then the recording gains reverberant energy, but the reverberation does not sound natural and does not complement the existing reverberation
Solution Approach 1:
The patent extracts the impulse response from the original recording and uses it to generate reverberation, rather than using artificial reverberation algorithms. This copying approach preserves the natural characteristics of the original acoustic space, making the added reverberation sound authentic and complementary to the existing signal.
Solution Approach 2:
The system uses the recording itself to generate the reverberation by extracting the impulse response from the original signal. The recording serves its own purpose of providing the reverberant characteristics, eliminating the need for external artificial reverberation devices and ensuring natural-sounding results.
2Reliability
If directional microphones or microphone arrays are used to reduce reverberation, then the direct sound component is enhanced, but the system complexity and hardware resources increase
Solution Approach 1:
The patent extracts the impulse response from the recorded signal and separates the direct sound component from the reverberant component through mathematical processing. This extraction approach reduces reverberation effects without requiring additional directional microphones or complex microphone arrays, simplifying the hardware while maintaining signal clarity.
Solution Approach 2:
The patent replaces the mechanical solution of using directional microphones or microphone arrays with a signal processing approach. By using mathematical operations on the recorded signal to extract and manipulate the impulse response, the system achieves reverberation reduction without the complexity of specialized hardware.
3Loss of information
If the impulse response is estimated from the entire signal, then the reverberant characteristics are captured, but the processing complexity and computational requirements increase
Solution Approach 1:
The patent divides the impulse response estimation into segments based on the structure of the recorded signal. By processing different portions of the signal separately and combining the results, the system captures complete reverberant characteristics while reducing the computational burden compared to processing the entire signal as a single block.
4Reliability
If reverberation is reduced in acoustic spaces, then the clarity and intelligibility of speech signals improve, but the sense of depth and envelopment is lost
Solution Approach 1:
The patent applies different processing to different components of the audio signal. The direct sound component is enhanced for clarity and intelligibility, while the reverberant component is carefully managed to maintain the sense of depth and envelopment. This local differentiation allows simultaneous improvement of intelligibility and preservation of spatial qualities.
Solution Approach 2:
The patent manipulates parameters of the impulse response and reverberant component to achieve optimal balance. By adjusting the timing, amplitude, and spectral characteristics of the reverberation, the system improves speech intelligibility while maintaining the perceptual qualities of depth and envelopment that provide spatial awareness.
Data Source
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AI summary
A method and apparatus for extracting and changing the reverberant content of an input signal is provided. The method of estimating an impulse response for a reverberant system includes sampling a signal from a reverberant system, having an impulse response, into a sequence of blocks, for each block of the sequence, determining a magnitude in dependence upon a magnitude of a previous block, forming an estimate of the impulse response using determined magnitudes as parameters for a finite impulse response filter. The method of creating a multi¬ channel signal using a signal with fewer channels from a reverberant system includes sampling the signal from a reverberant system, having an impulse response, into a sequence of blocks, for each block of the sequence, determining a magnitude in dependence upon a magnitude of a previous block, forming an estimate of the impulse response using determined magnitudes as parameters for a finite impulse response filter, applying an inverse of the estimated impulse response to the signal to derive at least one of a direct signal component and a reverberant signal component, and recombining the direct signal component and the reverberant signal component to create a multi-channel signal.