Directional Loudspeaker Using Horn and Wave Interference
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Solution Overview
Problem
Existing directional loudspeakers face challenges in maintaining directivity at higher frequencies, as the wavelength becomes too great for effective bundling, leading to the need for a large design.
Innovation Solution
A loudspeaker design incorporating an acoustic horn for higher frequencies and destructive interference between front and rear waves around an attenuation axis for lower frequencies, achieving directional effect across a wide frequency range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If bundling is used to achieve directional effect at higher frequencies, then the wavelength becomes too great for effective bundling, but the directional effect can no longer be reasonably obtained by bundling
Solution Approach 1:
The patent changes the operating parameters by introducing destructive interference between front and rear waves at specific frequencies. By controlling the phase relationship and timing of wave cancellation, the system maintains directional effect at lower frequencies where traditional bundling becomes ineffective due to excessive wavelength relative to speaker dimensions.
2Reliability
If a large design is used to maintain directivity at higher frequencies, then the directional effect is maintained, but the size of the loudspeaker increases
Solution Approach 1:
Instead of increasing physical dimensions to maintain directivity, the patent changes the acoustic parameter approach by using destructive interference of rear waves with front waves. This allows a compact speaker design to achieve directional control at lower frequencies through wave cancellation rather than physical size.
Solution Approach 2:
The patent converts the harmful rear waves, which normally cause omnidirectional sound radiation and reduce directivity, into a beneficial element. By timing the rear waves to destructively interfere with front waves at specific frequencies, the system uses these previously problematic waves to enhance directional control without increasing speaker size.
3Reliability
If destructive interference is used for lower frequencies, then directional effect is achieved, but the phase shift between rear waves and front waves must be precisely controlled
Solution Approach 1:
The system uses the natural propagation characteristics of sound waves and the inherent time delay between front and rear wave generation. By positioning the rear wave source and controlling its output timing, the system self-generates the necessary phase shift for destructive interference without requiring complex external phase control mechanisms.
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 design maintains directivity over a wide frequency range by combining horn effect for higher frequencies and destructive interference for lower frequencies, enhancing sound efficiency and reducing unwanted reflections.
Implementation Method 1
an acoustic horn which extends between a neck and a mouth along a horn axis, which neck is acoustically coupled to the front waves and which horn has a directional effect along the main axis for front waves lying in a second frequency range
Implementation Method 2
by means of a phase shift between the respective rear waves and front waves obtained by means of a difference between a rear propagation time to the attenuation axis for rear waves and a front propagation time to the attenuation axis for front waves, a directional effect along the main axis for front waves with a frequency in the third frequency range by destructive interference between the respective rear waves and front waves around the attenuation axis
Data Source
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AI summary
The invention relates to a loudspeaker for use in the audio spectrum with directional effect along a main axis extending from a front side of the loudspeaker, comprising: - a housing - at least one sound source arranged in the housing, which sound source is configured to produce sound waves substantially in a first frequency range lying between a lower frequency and an upper frequency, wherein the produced sound waves comprise front waves on the front side of the sound source and comprise rear waves on the rear side of the sound source, and - an acoustic horn which extends between a neck and a mouth along a horn axis, which neck is acoustically coupled to the front waves and which horn has a directional effect along the main axis for front waves lying in a second frequency range and having a frequency higher than a midfrequency lying between the lower and upper frequency, wherein the loudspeaker comprises an attenuation axis lying at an angle relative to, preferably opposite the main axis, and is configured to obtain for front waves and rear waves lying in a third frequency range and having a frequency lower than the midfrequency, and by means of a phase shift between the respective rear waves and front waves obtained by means of a difference between a rear propagation time to the attenuation axis for rear waves and a front propagation time to the attenuation axis for front waves, a directional effect along the main axis for front waves with a frequency in the third frequency range by destructive interference between the respective rear waves and front waves around the attenuation axis.