Speaker Calibration via Gain Control and Feedback
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Solution Overview
Problem
Existing technologies for achieving directivity using two speakers fail to maintain desired directivity characteristics due to variations in speaker manufacturing or changes over time, caused by differences in frequency characteristics and conversion efficiency.
Innovation Solution
A method for speaker calibration involving filter processing, gain multiplication, and gain control to ensure that the root mean square of sound signals collected at a mute position is minimized, using a device with filter processing units, speakers, a microphone, and a gain control unit to adjust gains dynamically based on collected sound signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If predetermined filter coefficients are used to achieve directivity, then sound is reproduced at high volume level toward the predetermined playback position, but directivity characteristics cannot be maintained when speaker characteristics vary due to manufacturing variations or changes over time
Solution Approach 1:
The system performs preliminary calibration by measuring the actual sound signals from both speakers at the mute position and pre-calculates the required gain adjustments. This preliminary action allows the system to compensate for manufacturing variations and time changes before normal operation begins, ensuring directivity characteristics are achieved and maintained.
Solution Approach 2:
The system uses feedback from the microphone measurements at the mute position to dynamically adjust the gain of each speaker channel. By continuously monitoring the actual sound output and comparing it with the desired directivity pattern, the system can adapt to variations in speaker characteristics and maintain optimal performance over time.
2Reliability
If gain is adjusted to compensate for speaker variations, then directivity characteristics can be maintained, but the system complexity increases due to additional calibration and control mechanisms
Solution Approach 1:
The system performs self-calibration by automatically measuring its own speaker characteristics and adjusting its own gain settings without requiring external intervention. The calibration process uses the speakers themselves as the measurement device, eliminating the need for complex external calibration equipment or manual adjustment procedures.
Solution Approach 2:
The system changes the gain parameter of each speaker channel based on measured characteristics. By adjusting this single critical parameter, the system can compensate for variations in speaker performance without requiring complex modifications to the overall system architecture or additional hardware components.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach allows for the achievement of desired directivity characteristics despite variations in speaker characteristics, ensuring effective sound distribution and maintaining optimal performance over time.
Implementation Method 1
a first filter processing unit generates a first filtered signal by filtering an input signal
Implementation Method 2
a second filter processing unit generates a second filtered signal by filtering the input signal
Implementation Method 3
a gain multiplication unit generates a gain multiplied signal by multiplying the second filtered signal by a gain
Implementation Method 4
a first speaker produces sound based on the first filtered signal
Implementation Method 5
a second speaker produces sound based on the gain multiplied signal
Implementation Method 6
a root mean square of a collected sound signal collected by a microphone installed at a mute position
Data Source
AI summary
There are included a first speaker processing step in which a first speaker 2 produces sound based on a first filtered signal, a gain multiplication step in which a gain multiplication unit 4 generates a gain multiplied signal by multiplying a second filtered signal by a gain, a second speaker processing step in which a second speaker 5 produces sound based on the gain multiplied signal, and a gain control step in which a gain control unit 7 controls the gain such that a root mean square of a collected sound signal collected by a microphone 6 installed at a mute position, which is a position at which the sound produced by the first speaker and the sound produced by the second speaker are to be muted, is relatively small.