Loudspeaker Transducer Orientation for Acoustic Interference Dip Elimination
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Solution Overview
Problem
Conventional loudspeakers mounted on surfaces, such as walls, experience a frequency response dip due to interference between direct and reflected acoustic energy, particularly at frequencies where the path length difference between the two is half a wavelength, leading to suboptimal sound distribution in listening areas.
Innovation Solution
The loudspeaker system includes a transducer positioned to face into the mounting surface, with a cover and engagement devices that allow the transducer to transmit acoustic energy directly into the surface, eliminating the interference dip by making the transducer and surface a coincident source, and optionally using a filter to address any resulting frequency response peaks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the transducer faces the listening area directly, then the sound transmission to listeners is improved, but a frequency response dip occurs due to interference between direct and reflected acoustic energy
Solution Approach 1:
Instead of facing the transducer towards the listening area (conventional approach), the patent inverts the configuration by facing the transducer towards the mounting surface. This causes the acoustic energy to be transmitted into the surface first, which then reflects it to the listening area, thereby eliminating the interference dip while maintaining sound transmission effectiveness.
Solution Approach 2:
The mounting surface acts as an intermediary medium. The transducer transmits acoustic energy into the surface, which then serves as a reflecting medium to deliver the sound to the listening area. This intermediary approach transforms the harmful direct-reflected interference into a beneficial single-path transmission through the surface.
2Reliability
If the transducer faces into the mounting surface, then the interference dip is eliminated, but the acoustic energy must propagate around the speaker enclosure which increases path complexity
Solution Approach 1:
The cover is divided into multiple sections (first section with mounting devices, second section, and third section) with each section containing passageways. This segmentation allows acoustic energy to propagate through multiple distributed paths around the enclosure, simplifying the overall acoustic field configuration while maintaining the benefit of eliminated interference dips.
Solution Approach 2:
The patent transitions from a one-dimensional direct front-firing acoustic path to a three-dimensional omnidirectional propagation pattern. By facing the transducer into the mounting surface and using the cover's passageways, acoustic energy radiates in multiple directions and dimensions, eliminating the need for complex single-path routing while achieving superior frequency response.
3Reliability
If the transducer transmits acoustic energy directly into the mounting surface, then the frequency response dip is prevented, but a frequency response peak may be introduced that requires additional filtering
Solution Approach 1:
The patent modifies the acoustic transmission parameters by changing the orientation of the transducer from facing the listening area to facing the mounting surface. This parameter change fundamentally alters the acoustic field distribution, eliminating the interference dip. The resulting frequency response peak is a manageable side effect that can be addressed through standard filtering techniques, representing an acceptable trade-off for achieving uniform frequency response across the critical dip frequency range.
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 enhances the frequency response by eliminating the dip and potentially introducing a peak, which can be filtered out, resulting in improved acoustic energy distribution and performance across the desired frequency range.
Implementation Method 1
The first loudspeaker transmits acoustic energy from the rear end towards the mounting surface to prevent an interference dip in a frequency response with the transmitted acoustic energy in the listening area. The interference dip occurring at frequencies where a path length difference between a direct wave of acoustic energy and reflected acoustic energy is equal to half of a wavelength.
Data Source
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AI summary
In at least one embodiment, a speaker system is provided. The speaker system includes a speaker enclosure having a front end, a rear end, and a first transducer. The front end is arranged to face a listening area. The rear end is arranged for being mounted to a mounting surface. The first transducer is positioned within the speaker enclosure for facing into the mounting surface such that the first loudspeaker transmits acoustic energy from the rear end towards the mounting surface to prevent a frequency response dip with the transmitted acoustic energy.