Phase Alignment of Multi-Driver Audio Systems Using Impulse Response Start Times
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Solution Overview
Problem
Existing audio systems face challenges in accurately aligning the phase and timing of multiple speakers due to limitations in delay finding methods, particularly in environments with significant high-frequency energy and acoustic reflections, leading to inaccurate delay values and degraded acoustic output.
Innovation Solution
A method and system for phase alignment that determine the start times of impulse responses for different frequency ranges, calculate delays based on these times, and adjust audio signal phases to achieve a target timing relationship between speakers, using a calibration device to equalize impulse responses and generate reference signals for precise phase alignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If conventional delay finding methods are used to align speaker timing, then the alignment process is simple, but the accuracy of delay values deteriorates in environments with high-frequency energy and acoustic reflections
Solution Approach 1:
The patent segments the impulse response analysis into multiple frequency bands (low-frequency and high-frequency portions) and applies different processing methods to each band. This allows the system to handle different frequency characteristics separately, improving overall measurement accuracy while maintaining operational simplicity through automated multi-band processing.
Solution Approach 2:
The system changes the parameter being measured from peak time to start time of the impulse response. This parameter change makes the measurement more robust against acoustic reflections and high-frequency energy, as the start time represents the actual arrival of the direct sound wave before reflections interfere with the signal.
2Device complexity
If peak finder methods are used for delay determination, then the method is straightforward, but the accuracy deteriorates when speakers require significant high-frequency energy
Solution Approach 1:
The impulse response is divided into frequency bands, with the low-frequency portion used for delay determination and the high-frequency portion for magnitude adjustment. This segmentation allows accurate delay measurement using low-frequency content that is less affected by reflections, while still utilizing high-frequency content for overall frequency response matching.
Solution Approach 2:
The patent uses an intermediary approach by introducing a model impulse response that serves as a reference. The measured impulse response is compared against this model, and the system automatically adjusts parameters to match, providing an automated intermediary process that eliminates manual peak finding while improving accuracy.
3Device complexity
If conventional phase alignment systems are used, then the system structure is simple, but the seamless integration between subwoofer and midrange speakers deteriorates due to inaccurate delay values
Solution Approach 1:
The patent applies segmentation by separating the impulse response into frequency bands and applying different adjustments to each band. The low-frequency band is used for delay alignment while the high-frequency band is used for magnitude equalization, ensuring seamless integration across the entire frequency spectrum between subwoofer and midrange speakers.
Solution Approach 2:
The system performs preliminary measurements and calculations to determine the optimal delay and magnitude adjustments before final alignment. By pre-calculating the required adjustments based on measured impulse responses and model comparisons, the system ensures accurate phase alignment is achieved before deployment, improving reliability without increasing operational complexity.
Data Source
AI summary
A method for phase alignment of audio signals using a first impulse response signal associated with a first frequency range and a second impulse response signal associated with a second frequency range is provided. The method includes determining a first start time for the first impulse response and a second start time for the second impulse response. The method further includes determining a delay based at least in part on a difference between the second start time and the first start time. The method further includes adjusting at least one audio signal phase for a first audio driver operating in the first frequency range with respect to a second audio driver operating in the second frequency range, where the adjusting of the at least one audio signal phase is based at least in part on the determined delay.