Audio Volume Control Circuit With Peak and RMS Safety Limiting
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Solution Overview
Problem
Conventional volume control systems in electronic devices limit audio output based solely on peak signal levels, leading to insufficient loudness in noisy environments due to conservative crest factor assumptions, which restrict the root mean square (RMS) power level below safe limits, causing users to perceive sound as not loud enough.
Innovation Solution
Implementing volume control circuits that consider both peak and power safety limits to determine the output audio signal's volume, allowing gradual gain adjustments to ensure the power safety limit is reached without exceeding the peak sound pressure limit, thereby setting the peak limit at the true safety threshold, even for higher crest factors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If conventional volume control systems limit audio output based solely on peak signal levels, then hearing safety is protected, but the perceived loudness is insufficient in noisy environments
Solution Approach 1:
The patent changes the control parameter from peak-only limiting to a dual-parameter system that controls both peak levels and RMS power levels. By introducing RMS power level measurement and control alongside peak limiting, the system achieves both hearing safety (through peak control) and sufficient perceived loudness (through RMS power control), resolving the contradiction between safety and loudness perception
Solution Approach 2:
The system implements feedback control by continuously measuring both peak levels and RMS power levels of the audio output, then adjusting the gain accordingly. The RMS power level measurement provides feedback on the actual perceived loudness, allowing the system to maintain optimal volume levels while staying within safe peak limits, thus resolving the contradiction between safety and perceived loudness
2Illumination intensity
If manual volume increase is implemented to compensate for noisy environments, then perceived loudness is improved, but user convenience deteriorates
Solution Approach 1:
The system performs self-service by automatically measuring the RMS power level of the audio output and adjusting the gain accordingly without requiring manual user intervention. The ambient noise measurement circuit and RMS power measurement circuit work together to automatically optimize the volume level, eliminating the need for users to manually adjust volume controls in different noise environments
Solution Approach 2:
The system uses feedback from ambient noise measurement circuits and RMS power level measurements to automatically adjust the audio output level. This closed-loop control system continuously monitors environmental conditions and audio output characteristics, then adjusts gain to maintain optimal perceived loudness without user intervention, resolving the contradiction between loudness and convenience
3Object-affected harmful factors
If peak safety limit is set conservatively, then hearing safety is ensured, but the power safety limit is not reached, causing user complaints about insufficient volume
Solution Approach 1:
The patent segments the volume control function into two independent but coordinated control mechanisms: peak level limiting and RMS power level control. By separating these functions, the system can set the peak safety limit conservatively for hearing protection while simultaneously optimizing the RMS power level to achieve sufficient perceived loudness, resolving the contradiction between safety and output effectiveness
Solution Approach 2:
The system changes from a single-parameter peak control approach to a two-parameter control approach that independently manages peak levels and RMS power levels. This allows the peak safety limit to be set at the true safety threshold while the RMS power level is optimized separately to maximize perceived loudness without exceeding safe peak levels, resolving the contradiction between safety and effectiveness
Data Source
AI summary
Volume control circuits for use in electronic devices are provided. Some embodiments of the present invention provide volume control circuits for use in electronic devices. The volume control circuits include a gain circuit, a limiter circuit, a power measurement circuit and a gain adjustment circuit. The gain circuit is configured to receive an input audio signal and amplify the input audio signal based on a gain. The limiter circuit is configured to limit the amplified input audio signal based on a peak safety limit and output an output audio signal having a peak value based on the peak safety limit. The power measurement circuit is configured to measure a power level of the output audio signal. The power level has an associated power safety limit. The gain adjustment circuit is configured to adjust the gain of the gain circuit responsive to the measured power. Related methods and electronic devices are also provided herein.