Loudspeaker System with Offset Rear Sound Outlets
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Solution Overview
Problem
Loudspeaker systems with low frequency sound sources typically have low directivity due to the large wavelengths of lower frequencies, which makes it difficult to achieve uniform sound distribution over a defined audience area, especially in large-scale or open-air events.
Innovation Solution
A loudspeaker system design featuring a front loudspeaker housing with at least one first loudspeaker and a rear bandpass loudspeaker housing with at least one second loudspeaker. The rear housing has two chambers with sound outlets arranged offset relative to each other, which allows for effective cancellation of rear sound radiation across an extended frequency range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a loudspeaker cabinet with small dimensions is used, then the device complexity is reduced, but the directivity is lost at low frequencies
Solution Approach 1:
The loudspeaker system is divided into multiple segments: a front loudspeaker housing and a rear loudspeaker housing with separate functions. The front housing provides omnidirectional low-frequency radiation, while the rear housing with bandpass configuration provides directional control, collectively achieving both compact form and frequency-independent directivity
Solution Approach 2:
The patent introduces a spatial dimension by offsetting the sound outlets of the rear loudspeaker housing relative to the front housing. This spatial offset creates frequency-independent directivity by ensuring that sound waves from both housings arrive at the audience area in phase across all frequencies, effectively adding a dimensional solution to the directivity problem
2Object-generated harmful factors
If cardioid loudspeaker arrangements are used to reduce rear sound, then the harmful sound emission is reduced, but the frequency range is limited
Solution Approach 1:
The patent changes the geometric parameters of the loudspeaker system by offsetting the sound outlets of the rear housing relative to the front housing. This parameter change creates a frequency-independent path difference that maintains rear sound cancellation across all frequencies, not just at a single frequency as in traditional cardioid arrangements
Solution Approach 2:
The rear loudspeaker housing is positioned asymmetrically with offset sound outlets relative to the front housing. This asymmetric arrangement creates different sound paths for front and rear radiation, achieving frequency-independent directivity and effective rear sound reduction across the entire frequency range
3Object-generated harmful factors
If the directivity is increased to reduce rear sound, then the noise protection is improved, but the sound distribution uniformity deteriorates
Solution Approach 1:
The loudspeaker system segments the sound radiation function into two parts: the front housing handles omnidirectional low-frequency radiation for uniform sound distribution, while the rear housing with offset outlets provides frequency-independent directivity control. This segmentation allows both uniform sound distribution and reduced rear sound emission to be achieved simultaneously
Solution Approach 2:
By introducing spatial offset between the sound outlets of the two housings, the patent creates a dimensional solution that achieves frequency-independent directivity without compromising sound distribution uniformity. The offset ensures that sound waves arrive in phase at the audience area while providing directional control to reduce rear sound emission
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 design achieves uniform, high attenuation of rear sound over an extended bandwidth range, reducing unwanted sound emission and allowing for more even sound distribution to the audience, while also enabling the use of higher frequency loudspeakers.
Implementation Method 1
The counter-sound cancels out the sound component emitted from the front low frequency loudspeaker to the rear
Implementation Method 2
This achieves a uniform, high attenuation of the return sound over an extended bandwidth range
Data Source
AI summary
A loudspeaker system has a front loudspeaker housing with at least one first loudspeaker and a rear loudspeaker housing with at least one second loudspeaker. The rear loudspeaker housing is a bandpass housing with at least one first chamber and at least one second chamber. The first chamber has a first sound outlet, and the second chamber has a second sound outlet. The first sound outlet and the second sound outlet are arranged offset relative to one another with respect to a main radiation direction of the front loudspeaker housing.