Stereo Unfold DSP for Spatial Audio Realism
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Solution Overview
Problem
Conventional stereo sound reproduction lacks spatial information, resulting in an artificial listening experience due to the inability to capture and recreate the ambient sound field, leading to a limited soundstage that fails to mimic real acoustic environments.
Innovation Solution
The Enhanced Stereo Unfold Technology uses psychoacoustic grouping and DSP algorithms to extract and add back ambient information, creating a three-dimensional soundstage by unfolding stereo signals in time, applicable to both standard loudspeakers and headphones without requiring prior information about the listener's physical properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional stereo reproduction is used, then the system is simple and compatible with standard speakers, but the soundstage is limited and lacks spatial realism
Solution Approach 1:
The patent segments the stereo signal into multiple unfolded feeds (at least 3) that are processed separately through DSP algorithms. Each feed contains extracted spatial information that is then recombined to create a three-dimensional soundstage, breaking down the complex spatial reproduction task into manageable signal components
Solution Approach 2:
The patent unfolds stereo signals in the time dimension to create additional spatial information. By processing signals through multiple time-delayed feeds and applying psychoacoustic grouping, the system transitions from two-dimensional stereo to three-dimensional spatial audio without adding physical speakers in different locations
2Reliability
If additional drivers aimed in different directions are used, then the three-dimensional soundstage is improved, but the device complexity and cost increase
Solution Approach 1:
The patent introduces psychoacoustic grouping as an intermediary process that mediates between the limited forward-aimed speakers and the listener's perception of three-dimensional space. The DSP algorithms create virtual spatial cues that trick the brain into perceiving sound sources in multiple directions, eliminating the need for physical speakers positioned around the listener
Solution Approach 2:
The patent replaces the mechanical solution of using multiple physically distributed speakers with a digital signal processing solution. DSP algorithms unfold the stereo signal in time and apply psychoacoustic grouping to create virtual spatial positioning, substituting mechanical speaker arrangements with computational audio processing
3Reliability
If psychoacoustic grouping is applied, then the soundstage moves outside the listener's head and clarity improves, but the processing requirements increase
Solution Approach 1:
The patent applies preliminary psychoacoustic grouping processing to the unfolded feeds before final playback. By pre-processing the signals to establish proper temporal and spectral relationships, the system ensures that the human brain naturally groups the sounds as coming from external sources, preparing the audio signal in advance for optimal spatial perception
Data Source
AI summary
The Stereo Unfold Technology solves the inherent problems in the stereo reproduction by utilizing modern DSP technology to extract information from the Left (L) and Right (R) stereo channels to create a number of new channels that feeds into processing algorithms. The Stereo Unfold Technology operates by sending the ordinary stereo information in the customary way towards the listener to establish the perceived location of performers in the sound field with great accuracy and then projects delayed and frequency shaped extracted signals forward as well as in other directions to provide additional psychoacoustically based clues to the ear and brain. The additional clues generate the sensation of increased detail and transparency as well as establishing the three dimensional properties of the sound sources and the acoustic environment in which they are performing. The Stereo Unfold Technology manages to create a real believable three-dimensional soundstage populated with three-dimensional sound sources generating sound in a continuous real sounding acoustic environment.