Loudness Compensation Filters for Playback Volume and Bass Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing audio signal processing technologies fail to accurately compensate for human loudness perception variations across different playback volumes, leading to uneven sound quality, particularly at low or high frequencies, due to coarse and empirical approximations of human auditory sensitivity.
Innovation Solution
A system that uses a loudness estimator to determine both production and playback loudness levels, generating a compensation filter based on equal-loudness contours to apply differential gains to frequency components, ensuring consistent perceived loudness across volume changes, while limiting excessive bass gain to prevent speaker damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If loudness compensation is applied to maintain perceived loudness across different playback volumes, then audio quality perception is improved, but power consumption increases due to the computational complexity of real-time loudness estimation and filter generation
Solution Approach 1:
The system pre-calculates and stores equal-loudness contour data for multiple reference loudness levels before runtime. During actual operation, the loudness estimator compares current playback loudness against these pre-computed reference levels to determine appropriate compensation filters, avoiding the need for complex real-time contour calculations and reducing processing power consumption
Solution Approach 2:
The system changes the parameter of reference loudness levels by providing a user-selectable range of reference loudness values that correspond to different listening environments. This allows the compensation algorithm to adapt to varying playback conditions without requiring continuous re-calculation of fundamental contour parameters, optimizing both accuracy and energy efficiency
2Measurement precision
If strong bass boost is applied to compensate for reduced sensitivity at low frequencies and low volumes, then perceived loudness balance is improved, but speaker distortion and potential damage occurs due to excessive bass gain
Solution Approach 1:
The system dynamically adjusts the bass boost amount based on the relationship between production loudness and playback loudness. When playback volume is significantly lower than production volume, the system applies stronger bass compensation; when playback volume is closer to production volume, the bass boost is reduced or eliminated. This dynamic adaptation prevents excessive bass gain that could cause speaker distortion while maintaining loudness balance across different playback conditions
Solution Approach 2:
The system uses feedback from the loudness estimator to continuously monitor the actual playback loudness level and adjust the compensation filter parameters accordingly. The estimated playback loudness feeds back into the filter selection process, creating a closed-loop system that prevents over-compensation and protects against speaker damage by adapting bass boost levels to actual playback conditions
3Measurement precision
If fine-tuning of frequency range and boost level is applied to match ear preferences, then subjective audio quality is improved, but device complexity increases due to multiple adjustable parameters and interpolation requirements
Solution Approach 1:
The system uses universal equal-loudness contour data that represents average human auditory characteristics across different loudness levels. By applying these standardized contours through automated filter generation, the system achieves consistent audio quality improvement without requiring multiple device-specific tuning parameters or complex user adjustment interfaces, reducing overall system complexity while maintaining high audio quality
Solution Approach 2:
The system performs automatic filter generation and selection based on loudness estimation, eliminating the need for manual fine-tuning by audio engineers or user adjustments. The automated process selects appropriate compensation filters based on the detected playback loudness level, providing consistent audio quality optimization without requiring complex user interfaces or manual calibration procedures
Data Source
Figure 1~2
Figure 3~4
Figure 5~7
AI summary
Provided are, among other things, systems, methods and techniques for loudness-based audio-signal compensation. According to one such system, an input line accepts an input audio signal; a loudness estimator, coupled to the input line, processes the input audio signal to obtain an audio playback loudness level and also provides a production loudness level for the input audio signal; and a filter generator/selector coupled to an output of the loudness estimator provides an audio compensation filter based on the production loudness level and the audio playback loudness level. The input signal is processed by the audio compensation filter to provide an output signal.