Headrest Dipole Loudspeaker Waveguide for Bass Sound Isolation
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Solution Overview
Problem
Existing loudspeakers struggle to create a personal sound cocoon with high sound pressure level (SPL) inside and low SPL outside, especially at bass frequencies, due to the impracticality of making a loudspeaker directive at these frequencies and the transmission of vibrations through the headrest.
Innovation Solution
A dipole loudspeaker is suspended directly in the headrest with acoustically non-transmissive portions guiding sound through open spaces, using a waveguide formation and a resilient material for the headrest structure to enhance sound path length and reduce vibration transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a dipole loudspeaker is mounted in a headrest with open spaces for sound travel, then sound can propagate freely, but acoustically non-transmissive portions create an acoustic short circuit that reduces effective output
Solution Approach 1:
A waveguide formation is introduced as an intermediary structure between the dipole loudspeaker and the headrest exterior. This waveguide extends the sound path length by routing sound waves through a controlled pathway, preventing the acoustic short circuit that would otherwise occur through the headrest structure, thereby maintaining sound output efficiency while managing acoustic energy properly
Solution Approach 2:
The sound propagation path is extended into a third dimension by using a waveguide formation that routes sound waves along a longer, more complex pathway rather than allowing direct transmission. This dimensional approach increases the effective sound path length and prevents acoustic short circuits through the headrest
2Stability of the object's composition
If the headrest structure is made rigid to provide stability, then mounting security is improved, but vibration transmission from the loudspeaker increases
Solution Approach 1:
The headrest structure employs different material properties in different regions: rigid materials are used in areas requiring structural stability and mounting security, while resilient materials are used in areas where vibration isolation is needed. This local differentiation allows the structure to simultaneously achieve stability and reduce harmful vibration transmission
Solution Approach 2:
The headrest is constructed using composite materials that combine rigid structural components with resilient vibration-damping components. This composite approach allows the headrest to maintain structural integrity while isolating and reducing the transmission of vibrations from the dipole loudspeaker
3Use of energy by moving object
If the sound path length is increased to improve SPL distribution, then sound pressure level within the cocoon is improved, but the physical space required increases
Solution Approach 1:
The waveguide formation is nested within the existing headrest structure, utilizing the available internal space efficiently. By routing the sound path through the headrest's internal geometry rather than requiring external space, the design increases sound path length and improves SPL distribution without increasing the overall volume of the headrest
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 configuration increases SPL within the personal sound cocoon and reduces SPL outside, while minimizing vibration transmission, achieving improved sound isolation and comfort.
Implementation Method 1
the dipole loudspeaker provides a personal loudspeaker that is created by using the sound created by a first radiating surface of the dipole loudspeaker to interfere with the sound produced by a second radiating surface of the dipole loudspeaker
Implementation Method 2
a waveguide formation to guide sound waves through the headrest structure
Implementation Method 3
a resilient material for the headrest structure to enhance sound path length and reduce vibration transmission
Data Source
Figure 1~2
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Figure 5~6
AI summary
There is provided a headrest housing a dipole loudspeaker for producing sound at bass frequencies in a forward direction and in a rear direction, a response 180 degrees out of phase from respective front and rear resonating surfaces. The headrest includes a waveguide formation to isolate sound from travelling through the headrest between the front surface and the rear surface. The headrest also includes an attachment formation, and the attachment formation suspends the first frame of the dipole loudspeaker and acts as a secondary suspension system. By including waveguide formations, the sound from the front surface of the dipole speaker can be guided outside of the headrest, wherein the shortest path from the front surface to the back surface is extended to be around the outside of the headrest. Guiding the sound path to be external to the headrest, prevents internal sound guiding compressing the intended path length. Also, with the structure of the headrest being formed from a resilient material to provide comfort to the listener, the attachment formations can be integrally formed from the resilient material with the resilient nature of the material providing the suspension to the first frame.