Virtual Height Filter for Immersive Audio Reproduction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing audio signal processing techniques for three-dimensional audio reproduction struggle to provide immersive sound experiences without requiring elevated loudspeakers, especially when dealing with audio content lacking dedicated height channels, and often compromise on vertical immersion effects.
Innovation Solution
The use of virtual height audio signal processing methods that apply virtual height filters derived from head-related transfer functions (HRTFs), allowing for independent optimization of vertical and horizontal sound localization, and the incorporation of decorrelation processing to enhance the reproduction of phantom sources, enabling immersive sound fields with conventional loudspeaker or headphone configurations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If filters are applied to restrict the effect to lower frequencies to reduce horizontal localization artifacts, then horizontal localization accuracy is improved, but vertical elevation effectiveness is compromised
Solution Approach 1:
The audio signal is segmented into different frequency bands, with low-pass filtering applied selectively to the height channel to reduce horizontal artifacts while preserving vertical elevation cues in the frequency domain
Solution Approach 2:
Different frequency processing strategies are applied to different spatial components: the height channel receives low-pass filtering locally to reduce horizontal localization artifacts, while the ambient channel preserves broader frequency content for vertical immersion
2Area of stationary object
If pseudo-stereo technique is used to spread audio signal over two loudspeakers, then horizontal coverage is improved, but vertical immersion effect is insufficient
Solution Approach 1:
The system transitions from two-dimensional horizontal stereo spreading to three-dimensional spatial audio by adding a virtual height dimension through signal processing, creating an immersive sound field that occupies vertical space without physical elevation of loudspeakers
3Reliability
If upward-firing loudspeaker driver is used to reflect height signals on ceiling, then vertical elevation effect is improved, but system complexity and calibration requirements increase
Solution Approach 1:
Instead of physically reflecting sound off the ceiling with upward-firing drivers, the system creates a virtual copy of the height signal through digital processing that simulates the acoustic effect of ceiling reflection, eliminating the need for complex physical hardware arrangements
Solution Approach 2:
The mechanical acoustic reflection system (upward-firing drivers requiring specific ceiling geometry and calibration) is replaced with a digital signal processing system that achieves the same vertical elevation effect through virtualization, reducing hardware complexity and installation requirements
4Measurement precision
If dedicated height channel is used for elevated loudspeaker reproduction, then vertical localization accuracy is improved, but hardware requirements increase
Solution Approach 1:
The system makes conventional horizontal loudspeakers multi-functional by using them to reproduce both horizontal and vertical spatial information through signal processing, eliminating the need for dedicated height channels and elevated loudspeaker hardware while maintaining vertical localization accuracy
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 approach provides a more accurate and immersive sound field experience by preserving vertical elevation effects even at non-optimal listening positions, reducing hardware requirements, and maintaining the natural localization of primary sound components while enhancing ambient components, all without the need for physically elevated loudspeakers.
Implementation Method 1
various techniques have been proposed for implementing audio signal processing based on Head-Related Transfer Functions (HRTF), such as for three-dimensional audio reproduction using headphones or loudspeakers
Implementation Method 2
an upward-firing loudspeaker driver can be used to reflect height signals on a listening room's ceiling
Data Source
AI summary
Systems and methods can provide an elevated, virtual loudspeaker source in a three-dimensional soundfield using loudspeakers in a horizontal plane. In an example, a processor circuit can receive at least one height audio signal that includes information intended for reproduction using a loudspeaker that is elevated relative to a listener, and optionally offset from the listener's facing direction by a specified azimuth angle. A first virtual height filter can be selected for use based on the specified azimuth angle. A virtualized audio signal can be generated by applying the first virtual height filter to the at least one height audio signal. When the virtualized audio signal is reproduced using one or more loudspeakers in the horizontal plane, the virtualized audio signal can be perceived by the listener as originating from an elevated loudspeaker source that corresponds to the azimuth angle.