Adjustable Loudspeaker Directivity via DSP and Flaps
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Solution Overview
Problem
Existing loudspeaker systems face limitations in controlling directivity, particularly at low frequencies due to physical constraints and high costs associated with digital signal processing, which restricts flexibility and effectiveness across the entire frequency range.
Innovation Solution
A sound system comprising orientable flaps and a Digital Signal Processor (DSP) control module that adjusts magnitude and phase parameters for both medium and treble sound transducers, allowing for variable directivity over a chosen angular sector, with the flaps and DSP module ensuring a constant sound level within the sector and significant attenuation outside it, and enabling a common frequency range that adapts based on orientation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If mechanical methods (sound horns, array-shaped transducers) are used to control directivity, then design simplicity and moderate cost are achieved, but the directivity is fixed and cannot be adjusted
Solution Approach 1:
The patent introduces orientable flaps that can be mechanically adjusted to different angular positions, transforming the fixed mechanical directivity control into a dynamic, adjustable system. The flaps can be oriented to different angles to control the sound emission directivity over chosen angular sectors, allowing the same physical configuration to provide multiple directivity settings.
2Adaptability or versatility
If variable-geometry horns or waveguides with orientable flaps are used, then directivity adjustability is improved, but performance is limited at medium frequencies
Solution Approach 1:
The patent combines mechanical directivity control (orientable flaps) with electronic directivity control (DSP processing) into a unified system. The flaps provide mechanical steering for high frequencies, while the DSP applies magnitude and phase parameters to transducers for electronic beamforming across the entire frequency range, including medium frequencies where the mechanical approach alone is insufficient.
Solution Approach 2:
The DSP acts as an intermediary that processes signals from multiple transducers and applies corrective magnitude and phase parameters. This electronic mediation compensates for the limitations of the mechanical flap system, particularly at medium frequencies, by using signal processing to achieve accurate directivity control across the full frequency spectrum.
3Adaptability or versatility
If DSP components are used to control directivity, then different directivities can be provided for the same physical configuration, but cost increases significantly
Solution Approach 1:
The system achieves multi-functionality by combining the mechanical flap assembly with DSP processing in a single integrated unit. The same physical transducer array serves both mechanical steering (via flaps) and electronic beamforming (via DSP), eliminating the need for separate systems and reducing overall cost while providing multiple directivity options.
Solution Approach 2:
The patent uses identical transducers arranged in a predefined physical configuration, copying the same hardware across multiple channels. The DSP then creates different directivity patterns by applying different magnitude and phase parameters to these identical transducers, providing multiple directivity options without requiring different physical hardware configurations for each mode.
4Adaptability or versatility
If identical transducers are used with DSP processing, then different directivities are achieved, but control of very high frequencies becomes impossible when wavelength is smaller than transducer size
Solution Approach 1:
The patent segments the frequency range and applies different control methods to different frequency bands. The mechanical flaps are effective for high frequencies (wavelength larger than transducer size), while the DSP processing handles medium and lower frequencies. This segmentation allows each method to operate in its optimal frequency range, achieving comprehensive control across the entire spectrum.
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
The system achieves effective directivity control from 300 Hz to frequencies exceeding 10 kHz, with adjustable directivity between 60° and 120°, overcoming the limitations of mechanical and electronic approaches by combining mechanical and electronic settings for enhanced performance.
Implementation Method 1
orientable flaps acting on a sound emission of the treble sound transducer so as to produce a sound emission directivity of the treble sound transducer over a chosen angular sector
Implementation Method 2
at least one Digital Signal Processor type control module acting on a signal addressed to the treble sound transducer and on a signal addressed to the medium sound transducer so as to apply in the common frequency range at least one magnitude parameter on the treble sound transducer (1) and/or on the medium sound transducer as well as at least one phase parameter
Implementation Method 3
at least one treble sound transducer (1) and at least one medium sound transducer (4), wherein the transducers are often identical
Data Source
AI summary
The disclosure includes a sound system comprising at least one Digital Signal Processor control module, acting on a signal to the high-frequency transducer and on a signal to a mid-frequency transducer so as to apply, in a common frequency range, at least one magnitude parameter as well as at least one phase parameter so as to produce a directivity along the same angular sector as a directivity produced by the orientable shutters.