Elevation Rendering via HRTF Filter Selection
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Solution Overview
Problem
Current audio processing technologies cannot effectively simulate the elevation of virtual sound sources in binaural audio or when all loudspeakers are in the same plane, lacking methods to physically elevate or lower sound sources for enhanced audio rendering.
Innovation Solution
The system employs a method to generate filtered audio signals by determining filter information based on input height information, using selected or modified filter curves to simulate the elevation of virtual sound sources, and applies these filters to audio input signals to create the illusion of elevated or lowered sound sources.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional amplitude panning techniques are applied to locate virtual sound sources between loudspeakers in a horizontal plane, then horizontal localization is achieved, but elevation rendering cannot be realized when all loudspeakers are in the same plane
Solution Approach 1:
The patent replaces the mechanical approach of physically elevating loudspeakers with a signal processing approach using HRTF-based filtering. Instead of changing the physical configuration of loudspeakers, the system uses digital filters to simulate elevation cues, substituting mechanical complexity with computational processing.
Solution Approach 2:
The patent changes the spectral parameters of the audio signal by applying HRTF filters that modify frequency content based on elevation angle. By adjusting filter characteristics according to the desired elevation, the system creates the perception of elevated sound sources without physical elevation of loudspeakers.
2Manufacturing precision
If HRTF filtering is applied to simulate elevation, then elevation rendering is achieved, but accurate filter selection requires precise determination of virtual sound source position
Solution Approach 1:
The patent pre-calculates and stores HRTF filters for multiple elevation angles before operation. During runtime, the system only needs to select from these pre-prepared filters based on the virtual sound source position, avoiding complex real-time filter design and reducing computational complexity while maintaining precision.
Solution Approach 2:
The patent introduces an intermediary module that maps virtual sound source coordinates to appropriate HRTF filter indices. This intermediary layer simplifies the relationship between position parameters and filter selection, making the system more manageable while preserving accuracy.
Data Source
Figure 1a~1b
Figure 1c
Figure 2
AI summary
An apparatus (100) for generating a filtered audio signal from an audio input signal is provided. The apparatus (100) comprises a filter information determiner (1 10) being configured to determine filter information depending on input height information wherein the input height information depends on a height of a virtual sound source. Moreover, the apparatus (100) comprises a filter unit (120) being configured to filter the audio input signal to obtain the filtered audio signal depending on the filter information. The filter information determiner (1 10) is configured to determine the filter information using selecting, depending on the input height information, a selected filter curve from a plurality of filter curves, or the filter information determiner (110) is configured to determine the filter information using determining a modified filter curve by modifying a reference filter curve depending on the elevation information.