Audio Probe Filtering via Empirical Impulse Response Characterization
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Solution Overview
Problem
Existing audio acquisition systems in three-dimensional environments, such as those used in television and cinematography, face limitations in achieving high-quality audio signals beyond 4 kHz due to reliance on theoretical filters that do not account for actual microphone capsule performance and environmental factors, leading to suboptimal directivity and signal quality.
Innovation Solution
The method involves empirically determining filters based on actual impulse responses of microphone capsules during a characterization step, using test signals to create FIR filters that account for the unique characteristics of each capsule and the probe's support, allowing for high-quality audio signal acquisition and maintaining directivity across a broader frequency range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If theoretical filters are used to ensure good directivity, then microphone directionality is improved, but audio signal quality deteriorates
Solution Approach 1:
The patent applies preliminary action by performing an empirical characterization of the probe in advance, measuring the actual impulse responses of all microphone capsules before use. These measured characteristics are stored and used to create customized filters that account for real-world variations in capsule performance, rather than relying on theoretical models. This pre-characterization ensures both accurate directivity and high signal quality during actual audio acquisition.
2Measurement precision
If theoretical filters are used to achieve good directivity, then directionality is improved up to certain frequencies, but directivity deteriorates beyond 4 kHz
Solution Approach 1:
The patent applies parameter changes by transitioning from theoretical filter parameters to empirically measured parameters. The impulse responses of the microphone capsules are measured across the entire frequency spectrum, capturing actual performance characteristics at all frequencies including high frequencies above 4 kHz. These measured parameters are then used to create filters that maintain accurate directivity across the full audible range.
Data Source
AI summary
Method for acquiring audio signals is described, wherein a microphone probe (11) equipped with a plurality (Y) of microphone capsules (B) detects a plurality of audio signals, and wherein said detected audio signals are combined together in order to obtain a virtual microphone signal. The latter is generated as a function of characteristic probe data (IRs) measured during a probe characterization step, wherein the signals detected by each microphone capsule (B) are measured following a corresponding predetermined test signal. An audio acquisition system is also described which allows to implement the method.