Virtual Surround Loudspeaker Using Segmented Dipole Beamforming
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Solution Overview
Problem
Traditional virtual surround sound systems face challenges in maintaining constant directivity across a wide range of frequencies, particularly at higher frequencies where the physical limitations of transducer spacing lead to irregular lobing and reduced sound quality.
Innovation Solution
The implementation of a virtual surround sound system using a combination of dipole beamforming, transducer directionality, and enclosure shading, with side-firing transducers and optimized frequency band management, allows for constant directivity across a wide frequency range by utilizing multiple methods to create intensity differences between ears.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If transducers are spaced closer together to optimize dipole beamforming at higher frequencies, then directivity control improves, but the physical possibility of placement becomes limited
Solution Approach 1:
The system divides the frequency spectrum into different bands and applies different transducer configurations for each band. Low frequency transducers are spaced differently than high frequency transducers, with each segment optimized for its specific frequency range. This allows directivity control to be maintained across the entire frequency spectrum without physical spacing constraints limiting high frequency performance.
Solution Approach 2:
Different transducers are assigned different spatial positions and orientations based on their frequency characteristics. Low frequency transducers may be spaced farther apart while high frequency transducers are positioned closer together with specific orientations. Each transducer location is locally optimized for its frequency band, achieving overall constant directivity across the full frequency range.
2Adaptability or versatility
If transducers are spaced farther apart to accommodate lower frequencies, then low frequency coverage improves, but higher frequency directivity deteriorates due to large spacing relative to wavelength
Solution Approach 1:
The frequency spectrum is segmented into low, mid, and high frequency bands, with dedicated transducers for each segment. Low frequency transducers are spaced to optimize bass response, while high frequency transducers are positioned and oriented to maintain proper spacing relative to their shorter wavelengths. This segmentation allows the system to cover a wide frequency range while maintaining directivity control at each frequency band.
Solution Approach 2:
The system transitions from a single-plane transducer arrangement to a three-dimensional configuration with transducers positioned at different heights, depths, and angles. This multi-dimensional positioning allows low frequency transducers to be spaced far apart for bass coverage while high frequency transducers are positioned closer together in specific spatial relationships that maintain proper spacing relative to their wavelengths, achieving wide frequency coverage without sacrificing high frequency directivity.
3Measurement precision
If dipole beamforming is used to create virtual surround, then interaural intensity difference improves, but frequency range is limited due to spacing constraints
Solution Approach 1:
The audio signal is divided into frequency bands, with dipole beamforming applied selectively to different segments. Low and mid-frequency signals use traditional dipole beamforming with larger transducer spacing, while high-frequency signals use processed signals from transducers positioned and oriented to maintain appropriate spacing relative to their wavelengths. This segmented approach maintains strong interaural intensity differences across the entire frequency range.
Solution Approach 2:
The system dynamically adjusts transducer excitation parameters including amplitude, phase, and timing based on frequency content. For each frequency band, the controller modifies these parameters to achieve optimal interaural intensity differences appropriate for that band's wavelength characteristics. This parameter adjustment allows dipole beamforming effectiveness to be maintained across a wide frequency range despite varying transducer spacing 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 approach enhances the virtual surround experience by maintaining sound quality and creating a more immersive audio environment with consistent directivity, even at higher frequencies, through the use of side-firing transducers and enclosure shading, which increases the sense of spaciousness and apparent source width.
Implementation Method 1
The transducers in a dipole pair are driven out of phase with each other in order to create a null for certain frequencies or channels
Implementation Method 2
a delay is used to steer the radial direction of the null. The result is that sound for certain frequencies or channels is more intense at one ear of the listener compared to the other ear
Data Source
AI summary
Various embodiments use combinations of different methods for creating virtual surround. Some of the methods used in various embodiments include: dipole beamforming, multi-stage arrays, transducer directionality, and enclosure shading. In general, each of these methods may operate over a specific frequency band in various embodiments. The use of multiple methods to create virtual sound can increase the virtual sound effect and better maintain sound quality compared to the use of a single method for creating virtual surround. Each method used to create virtual surround can be optimized for a specific system configuration based on factors such as the physical set-up of the transducers, the size and shape of the enclosure, and the input signal configuration. Various embodiments allow for an intensity difference to be created for a listener across a wide range of frequencies in order to produce constant directionality.