Audio Gain Control Recovery for Faster User Level Adjustment
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Solution Overview
Problem
Conventional sound signal processing apparatuses with automatic level control (ALC) functions struggle to quickly respond to user-initiated changes in input sound levels, leading to delayed recognition of steady sound levels after level adjustments.
Innovation Solution
The apparatus includes a first amplifier and a second amplifier, where the second amplifier adjusts gain at a higher speed when the user decreases the input level, allowing for rapid recovery to the original gain value, and at a lower speed when no user intervention is detected, improving response to changes in input sound levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the second amplifier increases gain at a slow speed during automatic level control recovery, then distortion is prevented and natural sound quality is maintained, but the response to user-initiated level changes is delayed
Solution Approach 1:
The patent applies dynamics by making the gain change speed variable rather than fixed. The control unit dynamically adjusts the gain change speed based on the operational context: using a first (faster) speed when user operation is detected and a second (slower) speed during automatic recovery. This resolves the contradiction by adapting the speed parameter to different operational states, achieving both fast user response and slow natural recovery when needed.
Solution Approach 2:
The patent changes the parameter of gain adjustment speed based on detected conditions. By monitoring whether user operation has occurred and switching between two distinct speed parameters (first speed and second speed), the system optimizes performance for different scenarios. This parameter change strategy allows the system to prevent distortion during automatic control while maintaining responsiveness to user inputs.
2Loss of time
If the gain is increased quickly after user operation, then the steady sound level is recognized faster, but distortion may occur during automatic level control
Solution Approach 1:
The system dynamically adjusts the gain change speed based on the operational state. When user operation is detected, the control unit selects the first (faster) gain change speed to quickly reach the desired level. When operating in automatic level control mode without user intervention, it selects the second (slower) speed to prevent distortion. This dynamic adaptation resolves the time-quality contradiction.
Solution Approach 2:
The control unit continuously monitors the operational state (whether user operation has occurred) and uses this feedback to adjust the gain change speed accordingly. This feedback mechanism ensures that the system responds appropriately to different conditions, selecting fast speed when user control is needed and slow speed when automatic control is active, thereby preventing distortion while maintaining responsiveness.
Data Source
AI summary
A sound signal processing apparatus includes: first amplifier which amplifies a sound signal, depending on an input level of the sound signal; and second amplifier which amplifies with a gain the sound signal amplified by first amplifier. Second amplifier automatically decreases the gain when a level of the sound signal is greater than an upper limit threshold, and second amplifier automatically increases the gain when the level of the sound signal is lower than the upper limit threshold and when the gain is lower than a predetermined value. When second amplifier increases the gain, second amplifier changes the gain at a first speed when a user has performed an operation to decrease the input level, and second amplifier changes the gain at a second speed lower than the first speed when the user has not performed the operation to decrease the input level.