Ribbed Baffle Loudspeaker for Ceiling Reflection Control
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Solution Overview
Problem
Ceiling and wall-mounted loudspeakers face challenges in providing optimal acoustics due to reflective environments, leading to sound wave cancellations and distortions, particularly in the 4 kHz-10 kHz frequency range, which affects vertical sound localization and spatial imaging.
Innovation Solution
A loudspeaker system with an obliquely mounted electro-acoustic transducer and a baffle featuring a three-dimensional ribbed portion and grooves to alter sound waves, creating an acoustic shadow that reduces ceiling reflections and enhances the spectral profile in the 4 kHz-10 kHz range, allowing direct sound radiation to reach the listener without electronic signal processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If ceiling or wall-mounted loudspeakers are used for aesthetic purposes, then the visual appearance is improved, but the acoustic performance deteriorates due to reflective boundaries causing sound wave cancellations and distortions
Solution Approach 1:
The patent applies reflective surfaces (acoustic mirrors) to deliberately reflect sound waves in controlled patterns, converting the harmful effect of reflections into a beneficial tool for shaping the sound field. The reflective surfaces create specific interference patterns that cancel unwanted reflections from ceiling and walls while enhancing direct sound propagation to listeners.
Solution Approach 2:
The patent modifies the spectral profile of the sound field by using reflective surfaces with specific geometries and materials that selectively reflect certain frequencies while absorbing others. This changes the frequency distribution parameters of the sound field to compensate for the mounting position, creating a spectral profile that mimics speakers mounted in optimal positions.
2Shape
If loudspeakers are mounted in ceilings or walls away from the listening plane, then aesthetic purposes are achieved, but vertical sound localization deteriorates due to altered spectral profiles in the 4 kHz-10 kHz range
Solution Approach 1:
The patent uses controlled reflections from acoustic mirrors to create constructive interference patterns that specifically enhance the spectral content in the 4 kHz-10 kHz range, which is critical for vertical localization. The harmful effect of being mounted away from the listening plane is converted into a beneficial tool for shaping the elevation cues.
Solution Approach 2:
The patent deliberately modifies the spectral profile parameters in the high-frequency range (4 kHz-10 kHz) using reflective surfaces with specific geometries. By controlling the phase and amplitude of reflected waves, the system changes the spectral characteristics to provide accurate elevation localization cues despite the non-standard mounting position.
3Measurement precision
If complex three dimensional audio signal processing and electronic filtering are used to improve spatial imaging, then vertical localization is improved, but device complexity and cost increase
Solution Approach 1:
The patent replaces complex electronic signal processing systems with passive acoustic structures (reflective surfaces and acoustic mirrors). Instead of using electronic filters and 3D audio processing circuitry to achieve spatial imaging, the system uses the physical principles of sound reflection, diffraction, and interference created by strategically placed acoustic surfaces.
Solution Approach 2:
The patent allows the acoustic environment itself to perform the spatial imaging function through natural sound wave propagation, reflection, and interference patterns. The reflective surfaces are positioned to automatically create the desired spectral profile and spatial characteristics without requiring active electronic control or processing.
4Area of stationary object
If directed speakers are used to produce sound fields oblique to adjacent surfaces, then the projection of speakers into living space is reduced, but attention to improving spectral profile for spatial imaging is neglected
Solution Approach 1:
The patent modifies the spectral profile parameters of the oblique sound field by using reflective surfaces with specific geometries and orientations. The acoustic mirrors are positioned to reflect sound waves at controlled angles while simultaneously shaping the spectral content in the 4 kHz-10 kHz range to provide accurate elevation cues.
Solution Approach 2:
The patent converts the oblique mounting configuration, which initially causes spatial imaging problems, into a beneficial arrangement by using reflective surfaces to create controlled interference patterns. The oblique position combined with strategic reflection creates a unique sound field distribution that improves both spatial imaging and reduces speaker projection into living space.
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 system improves spatial imaging by modifying the spectral profile, making the sound field indistinguishable from a speaker mounted in the listener's plane, enhancing the home theater experience by accurately localizing sound sources vertically.
Implementation Method 1
causes the oblique sound field to be diffracted creating an acoustic shadow that precludes ceiling reflections
Implementation Method 2
utilized scattering features to randomize the internal sound waves of a speaker, both to prevent the formation of standing waves and to diffuse the sound field
Data Source
AI summary
A loudspeaker system includes an enclosure having an open end defining a plane, a baffle, a loudspeaker operating in the 4 kHz to 10 kHz range, and a device, preferably a ribbed portion having a plurality of grooves, coupled to the baffle for modifying the spectral profile of the projected sound waves. The baffle includes first and second angled surfaces each oriented at an oblique angle with respect to the plane. The speaker is coupled to the first angled surface and the ribbed portion is coupled to the baffle along the intersection of the first angled surface and the second angled surface. When mounted in a wall or ceiling, the system projects a sound field substantially indistinguishable from that of a loudspeaker located within the listener's listening plane. The baffle can also have acoustic damping material attached thereto, with grooves formed therein, to prevent reflections of 4 kHz to 10 kHz sound.