Audio Playback Array Augmentation for Compact Spatial Filtering
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Solution Overview
Problem
Playback devices with a limited number of transducers face challenges in achieving desired spatial filtering effects due to the physical proximity of the transducers, leading to inadequate directionality and psychoacoustic experiences, particularly in compact form factors.
Innovation Solution
Employing an array transfer function that combines a lead array and augmentation arrays to drive audio output, where lead transducers primarily output audio channels while non-lead transducers provide offsetting audio to enhance directionality and spatial effects, using destructive or constructive interference to improve directivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If transducers are placed close together to reduce device size, then device compactness is improved, but spatial filtering effects and directionality deteriorate
Solution Approach 1:
The patent replaces traditional mechanical spatial filtering approaches with acoustic interference-based directionality control. By using array transfer functions that leverage destructive and constructive interference patterns, the system achieves precise spatial filtering without requiring large physical distances between transducers, thus resolving the contradiction between compact device size and effective spatial filtering.
Solution Approach 2:
The patent changes the operational parameters of the transducer array by introducing array transfer functions with specific phase and amplitude relationships. This allows the system to achieve enhanced directionality and spatial separation effects even when transducers are positioned close together, transforming the physical limitation into an opportunity for innovative acoustic control.
2Device complexity
If limited number of transducers is used to simplify device structure, then device complexity is reduced, but directionality and spatial separation deteriorate
Solution Approach 1:
The patent makes each transducer in the array serve multiple functions by applying array transfer functions that enable any transducer to contribute to multiple audio channels simultaneously. This multi-functionality allows a limited number of transducers to achieve enhanced spatial filtering and directionality effects that would traditionally require many more dedicated transducers.
Solution Approach 2:
The patent creates virtual copies of audio channels through acoustic interference patterns. By using destructive interference to cancel unwanted spatial components and constructive interference to enhance desired directions, the system effectively synthesizes multiple directional audio outputs from a limited physical transducer array, achieving the spatial separation of many channels with fewer physical 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
Enhances psychoacoustic experiences by increasing directivity and spatial separation of audio channels, particularly in the 250-500 Hz frequency range, resulting in improved sound localization and immersion.
Implementation Method 1
the second audio output at least partially cancels the first audio output along a spatial region offset from the first acoustic axis
Implementation Method 2
Employing an array transfer function that combines a lead array and augmentation arrays to drive audio output, where lead transducers primarily output audio channels while non-lead transducers provide offsetting audio to enhance directionality and spatial effects, using destructive or constructive interference to improve directivity
Data Source
AI summary
Systems and methods for providing augmented arrays for audio playback are disclosed. An example playback device includes a first transducer configured to output audio along a first acoustic axis and a second transducer configured to output audio along a second acoustic axis. The playback device is configured to receive a source stream of audio content including at least a first input channel and a second input channel. The device plays back first audio output via the first transducer based on the first input channel and directed along the first acoustic axis, and plays back second audio output via the second transducer based on the second input channel and directed along the second acoustic axis, wherein the second audio output at least partially cancels the first audio output along a first spatial region offset from the first acoustic axis.