Second-Order Filter Sections for Audio Elevation Modification
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Solution Overview
Problem
In movie and home theaters, loudspeakers are typically positioned behind screens, leading to an undesirable effect where viewers can discern that sound is coming from a source separate from the screen due to non-ideal loudspeaker placement, such as above or below an LED screen, disrupting the immersive experience.
Innovation Solution
A system and method utilizing digital filters, specifically second-order filter sections, to modify audio signals so that they are perceived as coming from a desired elevation, allowing loudspeakers to be positioned differently while maintaining an immersive sound experience by adjusting the audio signal to match the perceived sound source location.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If loudspeakers are positioned behind screens, then integration of visual and audio content is improved, but sound localization accuracy deteriorates
Solution Approach 1:
The patent applies parameter changes by modifying the audio signal's frequency spectrum through filtering techniques. Second-order filter sections are used to adjust spectral parameters, creating artificial elevation cues that change how the sound is perceived spatially. This allows the sound to be localized at a different apparent position than the physical speaker location, resolving the contradiction between screen integration and localization accuracy.
Solution Approach 2:
The patent introduces an intermediary processing stage between the audio signal and the listener. Digital filters act as mediators that transform the audio signal to create virtual sound source positions. This intermediary layer allows the physical speaker to remain behind the screen while the perceived sound origin appears to come from the screen area, maintaining both integration and localization accuracy.
2Ease of operation
If loudspeakers are positioned above or below screens, then installation flexibility is improved, but immersive sound experience deteriorates
Solution Approach 1:
The system changes audio signal parameters using second-order filters to create artificial elevation perception. By adjusting filter coefficients and frequency responses, the sound is made to appear as if it originates from the screen area rather than from speakers positioned above or below. This maintains the immersive experience while allowing installation flexibility.
3Adaptability or versatility
If audio signal is modified to change perceived sound source location, then loudspeaker placement flexibility is improved, but signal processing complexity increases
Solution Approach 1:
The patent segments the filtering process into multiple second-order filter sections. Each filter section handles a specific frequency range or aspect of the elevation modification, making the overall complex processing task manageable and modular. This segmentation allows for systematic design and implementation while achieving the desired spatial perception effects.
Data Source
AI summary
One embodiment provides a method comprising determining an actual elevation of a sound source. The actual elevation is indicative of a first location at which the sound source is physically located relative to a first listening reference point. The method further comprises determining a desired elevation for a portion of an audio signal. The desired elevation is indicative of a second location at which the portion of the audio signal is perceived to be physically located relative to the first listening reference point. The desired elevation is different from the actual elevation. The method further comprises, based on the actual elevation, the desired elevation and the first listening reference point, modifying the audio signal, such that the portion of the audio signal is perceived to be physically located at the desired elevation during reproduction of the audio signal via the sound source.