Audio Delay Parameter Setting for Indirect Sound Reduction
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Solution Overview
Problem
Existing techniques for reducing the influence of indirect sound on sound quality, such as those using FIR filters, are computationally complex and inefficient, especially at high sampling frequencies.
Innovation Solution
An audio apparatus with a delay processing unit and an adding unit that measures and adjusts impulse responses to minimize the impact of indirect sound, using a simpler configuration that includes a low-pass filter and multi-tap delay to process audio signals, thereby reducing computational complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If an FIR filter is used to reduce indirect sound influence, then accurate control of sound quality is improved, but computational complexity increases significantly
Solution Approach 1:
The patent segments the frequency spectrum by separating low-frequency components (processed through delay and addition) from high-frequency components (processed through notch filtering). This segmentation allows each frequency range to be handled by a simpler,针对性 processing method, avoiding the need for a complex full-band FIR filter while still effectively reducing indirect sound influence across the entire spectrum.
Solution Approach 2:
The patent changes the processing parameters by using a maximum delay time of 50ms or shorter, which is specifically optimized to match the auditory temporal resolution. This parameter optimization allows the system to effectively cancel indirect sound while maintaining computational efficiency, as the delay length is precisely tuned to the human ear's temporal characteristics rather than using a longer delay required by traditional FIR filters.
2Measurement precision
If the sampling frequency is increased to improve sound quality, then audio fidelity is improved, but computational complexity increases very large
Solution Approach 1:
The patent segments the processing into frequency-specific paths: low-frequency components are handled with simple delay-and-add operations, while high-frequency components are handled with notch filtering. This segmentation allows high sampling frequencies to be used for audio fidelity without proportionally increasing computational complexity, as each frequency band uses the most efficient processing method for its characteristics.
Solution Approach 2:
The patent optimizes the delay time parameter to 50ms or shorter, which is specifically tailored to auditory temporal resolution. This parameter optimization ensures that even at high sampling frequencies, the computational load remains manageable because the delay operations are precisely bounded, preventing the computational complexity from scaling linearly with sampling frequency.
3Object-affected harmful factors
If a delay time longer than auditory temporal resolution is used, then indirect sound cancellation is improved, but sound quality degradation occurs
Solution Approach 1:
The patent precisely optimizes the delay time parameter to match the auditory temporal resolution (50ms or shorter). This parameter optimization creates a precise boundary: delays within this range effectively cancel indirect sound by aligning with human temporal perception, while delays beyond this range cause perceptible sound quality degradation. The parameter is specifically tuned to exploit the temporal characteristics of human hearing.
Solution Approach 2:
The patent replaces the traditional approach of using long delays with a hybrid system that combines short delays (≤50ms) with frequency-selective notch filtering. This substitution maintains effective indirect sound cancellation by using the short delay to handle temporal aspects within auditory resolution, while the notch filter handles the spectral aspects, avoiding the need for excessively long delays that would degrade sound quality.
Data Source
AI summary
A method of setting a parameter for an audio apparatus including a delay processing unit which applies a delaying process and an amplifying process on an input audio signal in accordance with the set parameter, includes: performing a measuring process including: causing an outputting device to output measurement sound; and measuring a first impulse response at a sound receiving point; performing a specifying process including: analyzing the measured first impulse response; calculating a second impulse response at the sound receiving point when the outputting device outputs sound in case where a parameter is set in the audio apparatus and an audio signal indicative of the measurement sound is input to the audio apparatus; and specifying a parameter in accordance with the calculated second impulse response; and performing a setting process of setting the specified parameter in the delay processing unit.