Specific-Loudness Audio Gain Control for Artifact-Free Dynamics
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Solution Overview
Problem
Conventional audio dynamics processing introduces audible artifacts due to uncontrolled gain changes, as it does not assess psychoacoustically the time intervals for gain adjustments, leading to unwanted perceptible changes in audio signals.
Innovation Solution
An audio processing system analyzes audio signals to identify auditory events, using spectral analysis or a loudness domain approach to control dynamic gain parameters, ensuring that gain changes occur primarily around event boundaries, thereby reducing artifacts by delaying or smoothing gain adjustments until event transitions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If conventional audio dynamics processing applies gain changes continuously, then the audio signal can be adjusted in real-time, but audible artifacts are introduced due to uncontrolled gain changes
Solution Approach 1:
The patent segments the audio signal into distinct auditory events based on psychoacoustic criteria (onset, offset, and sustained portions). By identifying these segments, the system applies gain changes only during appropriate portions of the audio signal, avoiding artifacts during perceptually critical transitions. This segmentation allows real-time processing while preventing harmful gain changes during event boundaries that the human ear is sensitive to.
Solution Approach 2:
The patent performs preliminary detection of auditory events and their characteristics (onset, offset, duration) before applying gain changes. By pre-identifying where in the audio signal gain modifications will be perceptible, the system can plan and execute gain adjustments only during safe time intervals, preventing audible artifacts while maintaining real-time processing capability.
2Manufacturing precision
If audio processing introduces gain changes to control dynamic range, then audio level can be adjusted, but unwanted perceptible changes occur due to lack of psychoacoustic assessment
Solution Approach 1:
The patent changes the parameter of gain application timing based on psychoacoustic parameters of the audio signal (auditory event detection). By assessing the temporal and spectral characteristics of the audio signal to identify auditory events, the system dynamically adjusts when gain changes are applied, ensuring precision in gain control while avoiding perceptible artifacts during critical listening moments.
Solution Approach 2:
The patent uses feedback from auditory event detection to control gain application. The system continuously monitors the audio signal for auditory events and uses this information to modulate gain changes in real-time, creating a closed-loop system that prevents perceptible artifacts while achieving precise dynamic range control.
3Measurement precision
If spectral analysis is used to detect auditory events, then gain changes can be synchronized with perceived events, but computational complexity increases
Solution Approach 1:
The patent applies local quality analysis by performing spectral analysis only in specific frequency bands and time windows where auditory events are most likely to occur. Rather than analyzing the entire spectrum continuously, the system focuses computational resources on detecting events at onset and offset portions of sounds, achieving precise auditory event detection with reduced computational complexity.
Data Source
AI summary
In one disclosed aspect, dynamic gain modifications are applied to an audio signal at least partly in response to auditory events and/or the degree of change in signal characteristics associated with said auditory event boundaries. In another aspect, an audio signal is divided into auditory events by comparing the difference in specific loudness between successive time blocks of the audio signal.