Individual Sound Zones Through Frequency-Domain Signal Processing
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Solution Overview
Problem
Existing audio signal processing technologies struggle to provide effective multizone reproduction in enclosures without acoustic barriers, leading to significant cross-talk and inadequate acoustic separation of different acoustic scenes in nearby sound zones.
Innovation Solution
An apparatus and method that utilize an audio preprocessor to modify audio signals based on signal power and loudness, combined with filters and optional band splitters and spectral shapers, to generate loudspeaker signals that minimize acoustic leakage and enhance perceived acoustic contrast in multiple sound zones.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If loudspeakers are placed close to listeners to achieve better acoustic separation, then acoustic contrast is improved, but listener movement freedom deteriorates
Solution Approach 1:
The patent transitions from spatial separation (physical distance between loudspeakers and listeners) to frequency-domain separation using signal processing. By applying filters and processing audio signals in the frequency domain, the system achieves acoustic zone separation without requiring loudspeakers to be positioned close to listeners, thus maintaining listener movement freedom while improving acoustic contrast.
2Measurement precision
If directional loudspeakers with higher directivity are used for higher frequencies, then acoustic separation is improved, but frequency range limitation worsens
Solution Approach 1:
The patent divides the audio signal into different frequency bands using band splitters, allowing different processing strategies for different frequency ranges. This segmentation enables the system to achieve good acoustic separation across the entire audible frequency spectrum, not just in specific frequency ranges, by treating low, mid, and high frequencies differently according to their acoustic characteristics.
Solution Approach 2:
The patent applies spectral shaping and filtering operations that modify the frequency content and distribution of audio signals. By changing spectral parameters and applying frequency-dependent processing, the system achieves improved acoustic separation across all frequency ranges without being limited to higher frequencies only.
3Measurement precision
If audio signals are processed to minimize acoustic leakage, then acoustic contrast is improved, but signal processing complexity worsens
Solution Approach 1:
The patent applies audio preprocessing operations (normalization, band splitting, spectral shaping) before the main filtering and reproduction stages. By preparing the audio signals in advance with appropriate preprocessing, the system reduces the computational complexity required during real-time processing while achieving the desired acoustic contrast and minimizing acoustic leakage.
Data Source
AI summary
An apparatus for generating a plurality of loudspeaker signals from two or more audio source signals is provided. Each of the two or more audio source signals shall be reproduced in one or more of two or more sound zones, and at least one of the two or more audio source signals shall not be reproduced in at least one of the two more sound zones. An audio preprocessor is configured to modify each initial audio signal of the two or more initial audio signals depending on a signal power or a loudness of another initial audio signal of the two or more initial audio signals. A filter is configured to generate the plurality of loudspeaker signals depending on in which of the two or more sound zones the two or more audio source signals shall be reproduced and depending on in which of the two or more sound zones the two or more audio source signals shall not be reproduced.