Dual Loudspeaker Sound Generating Device for Headphones
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Solution Overview
Problem
Conventional head-mounted playing devices with sound generating devices suffer from significant sound signal attenuation in far-field directions and decreased sensitivity for medium and low frequency sounds due to phase interference between front and rear sound outlets, especially in noisy environments.
Innovation Solution
A sound generating device with two loudspeakers, where the rear cavity of one loudspeaker is connected to the front cavity of another, and both are coupled at a rear sound outlet, allowing for phase opposition and amplitude matching of sound signals, and a control apparatus that adjusts loudspeaker operation based on trigger signals to optimize sound radiation and sensitivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a single loudspeaker is used with front and rear sound outlets, then sound radiation can be attenuated in far-field directions, but sensitivity for medium and low frequency sound signals decreases due to phase interference
Solution Approach 1:
The sound generating device is divided into two separate loudspeakers (first loudspeaker and second loudspeaker) instead of using a single loudspeaker. Each loudspeaker has its own front and rear cavities, allowing independent control of sound signals from different sources. This segmentation enables the system to manage phase relationships more effectively while maintaining sound radiation attenuation.
Solution Approach 2:
The front cavity of the second loudspeaker is communicated with the rear cavity of the first loudspeaker, creating a combined acoustic path. This merging allows sound signals from both loudspeakers to interact constructively at the rear sound outlet, improving sensitivity for medium and low frequency signals while maintaining far-field attenuation through coordinated phase control.
2Object-affected harmful factors
If phase opposition is applied between front and rear sound outlets, then far-field sound radiation is attenuated, but near-field sensitivity decreases
Solution Approach 1:
Different phase relationships are applied to different sound outlets: the front sound outlet maintains standard phase relationships for good near-field sensitivity, while the rear sound outlet uses phase opposition specifically targeted at far-field directions. This local differentiation of phase characteristics allows the system to achieve far-field attenuation without compromising near-field sensitivity.
Solution Approach 2:
The patent introduces spatial dimensionality by using two loudspeakers positioned at different locations, creating a three-dimensional sound field distribution. This allows phase opposition to be applied selectively in different spatial directions, achieving far-field attenuation in horizontal directions while maintaining near-field sensitivity at the user's ear position.
3Reliability
If two loudspeakers are used with complex cavity connections, then sound sensitivity is improved, but device complexity increases
Solution Approach 1:
Each loudspeaker is designed with dual functionality: it can independently generate sound signals for both front and rear sound outlets through its front and rear cavities. The second loudspeaker's front cavity serves both as its own front output and as an extension of the first loudspeaker's rear cavity. This multi-functionality reduces the need for additional separate components while achieving the desired acoustic performance.
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
Significantly attenuates sound radiation in far-field directions while improving sound sensitivity at the human ear by reducing phase interference and enhancing sound signal intensity, especially in noisy conditions.
Implementation Method 1
a phase of a sound signal output from the rear cavity of the first loudspeaker is opposite to a phase of a sound signal output from the front cavity of the second loudspeaker
Data Source
AI summary
Disclosed in the present disclosure is a sound generating device, a control apparatus thereof and a playing device, the sound generating device comprises: a housing provided with a front sound outlet communicated with a front cavity of a first loudspeaker and a rear sound outlet communicated with a rear cavity of the first loudspeaker and a front cavity of a second loudspeaker, a rear cavity of the second loudspeaker is enclosed, a phase of a sound signal output from the rear cavity of the first loudspeaker is opposite to that from the front cavity of the second loudspeaker, and is opposite to that from the front cavity of the first loudspeaker. The present disclosure can attenuate the sound radiation to the outside, weaken the attenuation of a far-field sound signal and improve the sensitivity of a sound signal at the human ear.