Listening-Position Loudness Correction for Audio Signal Processing
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Solution Overview
Problem
Conventional audio signal processing devices do not account for the actual sound volume at the listening position, leading to inadequate loudness correction due to varying distances between the listener and speakers, as well as non-linear output levels from speakers, resulting in reduced audibility of low-frequency and high-frequency components at low sound volumes.
Innovation Solution
An audio signal processing device that measures sound volumes at the actual listening position and adjusts the audio signal levels based on these measurements, using a sound volume setting value and a sound volume measuring unit to perform loudness corrections, ensuring proper frequency characteristics in line with human auditory sensitivity, regardless of speaker efficiency or listening environment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional audio signal processing devices perform loudness correction based on equal loudness curve, then frequency characteristics are corrected according to standard, but actual sound volume at listening position is not taken into consideration
Solution Approach 1:
The patent replaces the theoretical equal loudness curve-based correction with actual acoustic measurements taken at the listening position using a microphone. This substitutes the mechanical/mathematical model approach with direct physical measurement, allowing the system to adapt to real-world variations in speaker efficiency, room acoustics, and listening distance.
Solution Approach 2:
The system uses a microphone to measure the actual sound output at the listening position and feeds this information back to the audio signal processing device. This feedback loop enables dynamic adjustment of loudness correction parameters based on real measurements rather than relying solely on theoretical models.
2Adaptability or versatility
If speakers are placed at varying distances from listening position, then setup flexibility is improved, but sound volume at listening position varies making loudness correction inadequate
Solution Approach 1:
The system performs self-calibration by automatically measuring its own output at the listening position using the microphone. The audio signal processing device plays test signals and measures the actual sound pressure level, then uses this information to automatically adjust loudness correction parameters without requiring manual calibration or user knowledge of acoustic principles.
Solution Approach 2:
The system dynamically changes the loudness correction parameters based on measured sound pressure levels. By adjusting equalization curves and gain settings according to actual measurements rather than fixed specifications, the system adapts to different speaker placements, room acoustics, and listening positions.
3Adaptability or versatility
If speakers have non-linear output characteristics, then speaker design flexibility is improved, but loudness correction becomes inaccurate at different input levels
Solution Approach 1:
The system performs preliminary measurements of speaker output characteristics across different input levels before normal operation. By characterizing the non-linear behavior in advance and storing this information, the system can pre-compensate for distortions and apply appropriate correction curves during actual audio playback.
Solution Approach 2:
The loudness correction system dynamically adjusts its parameters based on the actual input level being played. Rather than using fixed correction curves, the system modifies equalization and gain settings in real-time according to the measured output characteristics at the current operating point, accommodating non-linear speaker behavior.
Data Source
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AI summary
An audio signal processing device includes an audio signal processing unit which performs signal processing on an audio signal, a sound volume setting receiving unit which receives a sound volume set value, and a sound volume measuring unit which measures a sound volume at a listening position. The audio signal processing unit performs a loudness correction which increases a level of the audio signal in a prescribed frequency range as the sound volume set value decreases. The sound volume measuring unit measures sound volumes corresponding to plural respective sound volume set values at the listening position. The audio signal processing unit sets a level adjustment amount to be used in performing the loudness correction based on the sound volume set value received by the sound volume setting receiving unit and the measurement sound volumes of the sound volume measuring unit.