Variable-Width Constant Coverage Horn for Uniform Vertical SPL
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Solution Overview
Problem
Conventional constant directivity horns exhibit significant variations in sound pressure level (SPL) across different areas of the vertical coverage, with the upper portion often providing less or no useful sound pressure due to increased distance, leading to inconsistent SPL distribution among listeners.
Innovation Solution
A loudspeaker apparatus featuring a variable-width slot between the throat and bell, with a narrower lower portion and wider upper portion, creating a more favorable acoustic path for sound energy to reach farther audience areas, thus maintaining consistent SPL distribution across the intended audience area.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a fixed-width diffraction slot is used in a constant directivity horn, then the horn structure is simple and easy to manufacture, but the sound pressure level distribution becomes inconsistent across the vertical coverage area
Solution Approach 1:
The slot width is varied locally along the vertical height of the horn. The upper portion has a greater width than the lower portion, creating different acoustic properties in different regions. This local variation compensates for the distance-related SPL attenuation in the upper coverage area while maintaining appropriate coverage in the lower area.
2Area of stationary object
If the upper portion of the vertical coverage directs sound to farther areas, then the overall coverage area is expanded, but the sound pressure level reaching those areas decreases
Solution Approach 1:
The slot width parameter is changed along the vertical direction of the horn. By increasing the slot width in the upper portion, the acoustic impedance and radiation characteristics are modified to compensate for the increased distance to the coverage area, thereby maintaining adequate SPL levels.
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 variable-width slot design ensures more consistent sound pressure level distribution across both near and far audience areas, offsetting attenuation due to distance, resulting in a more rectangular-shaped coverage area with improved sound energy delivery to the intended audience.
Implementation Method 1
creating a more favorable acoustic path for sound energy to reach farther audience areas
Data Source
AI summary
An example apparatus may include one or more of a throat that includes an opening that receives sound, a bell that directs the sound, a mouth opening that outputs the sound, and a variable-width slot disposed between the throat and the bell which directs the sound, wherein the variable-width slot may include a lower portion with a first width and an upper portion with a second width which is greater than the first width.