Nonlinear Distortion Estimation and Parameter Tuning for Loudspeaker Boosting
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Solution Overview
Problem
Existing methods for estimating nonlinear distortion in loudspeaker systems are inadequate, particularly in accurately measuring nonlinear distortion and tuning parameters for boosting sounds below the lower cutoff frequency, as they fail to effectively separate nonlinear distortion products from linear contributions and do not adequately manage parameter settings to minimize distortion.
Innovation Solution
A method and system that generate a test signal with simultaneous audible tone signals, including a fundamental tone and harmonics, to estimate nonlinear distortion by performing spectral analysis and calculating a separation ratio, and tune parameters by comparing nonlinear distortion values with and without boosting, ensuring the difference is below a threshold to minimize distortion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a multi-tone test signal is used to estimate nonlinear distortion, then the measurement covers the audio frequency range similar to musical signals, but the nonlinear distortion products overlap with the tone signal frequencies making accurate separation difficult
Solution Approach 1:
The patent segments the test signal into multiple individual tone components rather than using a continuous multi-tone signal. By presenting tones sequentially and analyzing each separately, the method avoids the overlap problem where distortion products from multiple simultaneous tones would contaminate each other's frequency regions. This segmentation allows precise measurement of distortion products for each tone without interference from other tone components.
Solution Approach 2:
The patent applies preliminary action by pre-calculating and storing the expected frequency locations of distortion products for each tone before actual measurement. The system prepares lookup tables containing the theoretical harmonic and intermodulation distortion frequencies, then uses these pre-computed values to guide the measurement and analysis process, enabling efficient identification and separation of actual distortion products from the measured spectrum.
2Illumination intensity
If boosting is applied to enhance sounds below the lower cutoff frequency, then the low-frequency response is improved, but nonlinear distortion increases
Solution Approach 1:
The patent implements feedback by measuring the actual nonlinear distortion produced when boosting is applied, then using this measurement information to optimize the boosting parameters. The system continuously monitors distortion levels and adjusts the boosting algorithm to achieve the best compromise between low-frequency enhancement and distortion control, rather than using fixed boosting parameters.
Solution Approach 2:
The patent applies parameter changes by systematically varying the boosting algorithm parameters (such as boost amount, frequency range, and processing gain) and evaluating the resulting distortion levels for each parameter setting. This allows optimization of the boosting parameters to achieve maximum low-frequency enhancement while keeping distortion below acceptable thresholds.
3Ease of operation
If existing distortion estimation methods are used, then the measurement process is simple, but the accuracy of separating nonlinear distortion from linear contributions is insufficient
Solution Approach 1:
The patent introduces an intermediary computational process that acts as a mediator between the simple measurement setup and accurate distortion estimation. The system uses intermediate calculations including spectral analysis, comparison with pre-computed distortion product patterns, and mathematical separation algorithms to bridge the gap between the simple measurement process and high-accuracy distortion quantification.
Data Source
AI summary
Embodiments for estimating nonlinear distortion and for tuning parameter(s) for boosting sounds are described. A test signal including at least two simultaneous audible tones is generated. One tone is a fundamental tone and others are harmonics of the fundamental tone. The ratio of the number of nonlinear distortion products not coincident with the frequencies of the tones to the number of all the products is, as an example, greater than 0.80. A spectral analysis is performed on the response of a loudspeaker to the test signal. A nonlinear distortion value is estimated by regarding the energy at harmonic frequencies of the fundamental tone signal but not at the frequencies of the tone signals as contribution from the nonlinear distortion. A subjectively correlated measure of nonlinear distortion is obtained for tuning a parameter for boosting low frequency outputs of one or more loudspeakers.