Virtual Height Filter for Ceiling-Reflected Audio
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Solution Overview
Problem
Current spatial audio systems are limited in home environments due to the absence of overhead speakers, which prevents full exploitation of adaptive audio content, and there is a need for a method to reproduce height information using upward-directed speakers that can reflect sound off upper surfaces.
Innovation Solution
The implementation of upward-firing speakers with a virtual height filter, based on a directional hearing model, to simulate overhead sound by reflecting sound off the ceiling, and incorporating a desired frequency transfer function directly into the transducer design to filter direct sound components from height sound components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If overhead speakers are used to playback height sound, then height information is accurately reproduced, but system cost and installation complexity increase
Solution Approach 1:
The patent redirects sound propagation from a vertical dimension (overhead speakers playing sound directly downward) to a horizontal dimension (upward-firing speakers playing sound at an angle toward the ceiling for reflection). This dimensional change allows height information to be reproduced using floor-standing speakers instead of overhead speakers, reducing installation complexity while maintaining spatial audio accuracy.
2Adaptability or versatility
If upward-firing speakers are used to reflect sound off the ceiling, then overhead speaker functionality is simulated, but direct sound components interfere with height sound components
Solution Approach 1:
The patent extracts and removes the harmful direct sound components from the audio signal sent to upward-firing speakers. By applying a filter that eliminates frequencies characteristic of direct sound (typically lower frequencies that travel directly to the listener), only the desired reflected height sound components remain, preventing interference while maintaining the simulated overhead effect.
Solution Approach 2:
The patent introduces a filter as an intermediary element between the audio source and the upward-firing speakers. This filter acts as a mediator that processes the audio signal to remove direct sound components before the sound reaches the speakers, thereby preventing the harmful interference from occurring in the first place.
3Measurement precision
If a filter is applied to remove direct sound components, then height sound quality is improved, but signal processing complexity increases
Solution Approach 1:
The patent applies the filter in advance to the audio signal before it is sent to the upward-firing speakers. This preliminary filtering action removes direct sound components proactively, preventing them from reaching the listeners and interfering with height sound perception. By doing the filtering beforehand rather than trying to correct the interference afterward, the solution simplifies the overall processing requirements.
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
This solution allows for the reproduction of full spatial information in listening environments with limited speaker arrays by providing height cues through reflected sound, enhancing the perception of overhead audio components and optimizing the playback of adaptive audio content.
Implementation Method 1
upward-firing speakers that reflect sound waves off of a ceiling to a listening location
Data Source
AI summary
Embodiments are directed to speakers and circuits that reflect sound off a ceiling to a listening location at a distance from a speaker. The reflected sound provides height cues to reproduce audio objects that have overhead audio components. The speaker comprises upward firing drivers to reflect sound off of the upper surface and represents a virtual height speaker. A virtual height filter based on a directional hearing model is applied to the upward-firing driver signal to improve the perception of height for audio signals transmitted by the virtual height speaker to provide optimum reproduction of the overhead reflected sound. The virtual height filter may be incorporated as part of a crossover circuit that separates the full band and sends high frequency sound to the upward-firing driver.