Acoustic Signal Gain Control for Smooth Source Switching
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Solution Overview
Problem
Existing acoustic devices experience volume inconsistencies when switching between different acoustic sources due to differences in signal characteristics, leading to user discomfort and potential signal saturation.
Innovation Solution
An acoustic device with averaging and gain correction mechanisms that adjust signal levels based on threshold values, allowing for smooth transitions between sources by averaging signal levels over different time periods and adjusting gain accordingly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the gain is calculated from the signal level in a predetermined period to enable automatic volume adjustment, then the volume consistency between different acoustic sources is improved, but the signal level changes greatly in musical pieces with large signal level variations, causing user discomfort
Solution Approach 1:
The patent applies dynamics by making the gain calculation period adaptive rather than fixed. The calculation period is dynamically adjusted based on the signal level variation rate: when signal levels change rapidly (high variation rate), the calculation period is shortened to track changes more closely; when signal levels are stable, the calculation period is extended for smoother control. This dynamic adaptation resolves the contradiction by enabling reliable volume consistency while maintaining user comfort during musical pieces with large signal level variations.
Solution Approach 2:
The patent changes the parameter of gain calculation period based on signal characteristics. By monitoring the signal level variation rate and adjusting the calculation period accordingly, the system optimizes the balance between volume consistency and user comfort. This parameter change allows the AGC to adapt to different signal types (e.g., music with large variations vs. speech with small variations), resolving the technical contradiction.
2Device complexity
If the signal level correction is not performed in the same acoustic source, then the processing complexity is reduced, but the signal level becomes excessively high to cause saturation and allophones
Solution Approach 1:
The patent applies preliminary action by performing signal level correction within the same acoustic source before saturation occurs. The system continuously monitors the signal level and applies gain adjustment in real-time during the reproduction of each acoustic source, preventing excessive signal levels and saturation. This preliminary correction ensures reliable signal processing while maintaining manageable processing complexity through efficient real-time control.
Solution Approach 2:
The patent implements feedback control where the signal level is continuously monitored and the gain is adjusted based on the monitored levels. The AGC circuit uses feedback from the signal level detection to dynamically adjust the gain, preventing saturation while maintaining optimal signal levels. This feedback mechanism resolves the contradiction by ensuring reliable saturation prevention without requiring overly complex processing.
3Ease of manufacture
If fixed volume adjustment parameters are set at the design stage for each acoustic source, then the manufacturing process is simplified, but the parameters cannot be changed after shipment to adapt to different signal characteristics
Solution Approach 1:
The patent applies self-service by enabling the acoustic device to automatically adjust volume parameters after shipment without requiring manual reconfiguration or complex manufacturing processes. The AGC circuit autonomously adapts to different acoustic sources by analyzing their signal characteristics and adjusting the gain calculation period accordingly. This self-service capability resolves the contradiction by maintaining manufacturing simplicity while achieving high adaptability through automatic post-shipment parameter adjustment.
Data Source
AI summary
An acoustic device, which reproduces an acoustic signal of one acoustic source selected from a plurality of acoustic sources. A first averaging unit averages signal levels of the acoustic signal for a first time period to obtain a first average signal. A second averaging unit averages the signal levels for a second time period shorter than the first time period to obtain a second average signal. A selecting unit selects either the first average signal or the second average signal as one signal having a signal level higher than the other. A gain decreasing unit decreases a gain of the acoustic signal according to the signal level of the one signal if the signal level of the one signal is higher than a threshold value determined according to the one acoustic source. A correcting unit corrects the signal levels of the acoustic signal according to the gain.