Loudspeaker Wave Front Shaping Device for Uniform SPL
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional loudspeakers with wave front shaping devices produce sound waves with circular segment cross sections that often exhibit undesirable peaks or drops in sound pressure level (SPL) at off-axis angles, and the SPL at off-axis angles can be higher than near the central axis, leading to uneven sound distribution across frequencies.
Innovation Solution
A wave front shaping device with a sound channel divided into multiple sub-channels by divider walls, where the side walls of each sub-channel converge towards each other from the entrance to the exit, transforming a flat wave front into a cylindrical segment shape, maintaining a consistent wave front surface area along the axial length to prevent sound wave compression and ensuring a uniform SPL across frequencies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the wave front shaping device uses a simple sound channel without divided sub-channels, then the device complexity is reduced, but the sound pressure level shows disturbing peaks or drops at certain off-axis angles for certain frequencies
Solution Approach 1:
The sound channel is divided into multiple sub-channels by divider walls extending from the entrance opening to the exit opening of the wave front shaping portion. This segmentation allows independent control of sound paths, eliminating SPL peaks and drops at off-axis angles by ensuring consistent phase relationships across different frequency ranges.
2Manufacturing precision
If the side walls of sub-channels are parallel, then the manufacturing precision is improved, but the beam width angle varies with frequency instead of maintaining a consistent 90° angle
Solution Approach 1:
The side walls of each sub-channel are designed to converge towards each other from the entrance opening to the exit opening, creating an asymmetric trapezoidal cross-section. This asymmetric geometry transforms the flat wave front into a cylindrical segment wave front with a consistent beam width angle of approximately 90° across all audible frequencies.
3Ease of operation
If the wave front surface area increases along the axial length of sub-channels, then the sound distribution is improved, but sound wave compression occurs causing SPL peaks at certain frequencies
Solution Approach 1:
The cross-sectional area of each sub-channel is carefully controlled to maintain substantially constant wave front surface area along the axial length. This parameter control prevents sound wave compression while still achieving proper sound distribution, thereby eliminating SPL peaks at certain frequencies.
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 solution achieves a consistent beam width angle of approximately 90° for all audible frequencies, avoiding SPL peaks or drops at off-axis angles and ensuring that the SPL at off-axis angles does not exceed the on-axis SPL, resulting in a more uniform and expected sound distribution.
Implementation Method 1
a wave front shaping portion arranged to transform a substantially flat wave front of a loudspeaker into a wave front having a cross section, seen in at least one direction, in the shape of a circular segment
Data Source
Figure 1~2
Figure 3~4
Figure 5A
AI summary
A loudspeaker comprising a sound channel extending between the vibrating region of a membrane and the outer side of the loudspeaker, the central axis of said sound channel extending perpendicular to the membrane, wherein said sound channel comprises a wave front shaping portion arranged to transform the substantially flat wave front of the produced sound emitted from the membrane into a wave front having a cross section, seen in at least one direction, in the shape of a circular segment, wherein said wave front shaping portion of said sound channel is divided into multiple sub-channels by divider walls, wherein said divider walls extend from an entrance opening of said wave front shaping portion to an exit opening of said wave front shaping portion, wherein, seen in cross section in said at least one direction, the side walls of each sub-channel converge towards each other from the entrance opening to the exit opening of said wave front shaping portion, wherein the centre line of each of said divider walls, seen in cross section in said at least one direction, converge towards each other adjacent the exit opening of said wave front shaping portion.