Overview
- The modern ubiquity of miniaturized speakers (in mobile phones, mobile music players, hearing aids, bluetooth headsets, and more) has exposed their many weaknesses, and dramatically diminished the expectations of what is possible.
- The heart of the problem is their traditional “balanced armature” or “voice coil” designs. Although balanced armature designs can deliver high acoustic power, they suffer from frequency response and distortion issues due to high moving mass (since an armature moves the drive rod, which in turns moves the diaphragm). Because of this, “balanced armature” designs (eg; combining two or more “balanced armature” drivers in one speaker) have limited, but not resolved the inherent limitations. Voice Coil designs, on the other hand, while more easily tuned at large size, suffer from poor sound quality at a very small size (below 8mm), due to the lack of external air (for in-ear applications), and the insufficiency of a central magnetic pole.
- SWAT (Sub Wavelength Acoustic Technology) Balanced Diaphragm MicroSpeakers deliver flatter frequency response over a wider frequency range, and are more efficient and reliable — all without sacrificing space and geometry.
Technology & Applications
The remarkable performance of the SWAT MicroSpeaker is due to its revolutionary design in which moving mass — and thus mechanical bias on moving parts — is extremely low. The focus on low moving mass contributes to the SWAT MicroSpeaker’s high efficiency.
Greater efficiency is also achieved by providing a sound conduction pathway through the magnetic structure in which the diaphragm is balanced, thus enabling the sound-producing (or receiving) balanced diaphragm element to be located entirely within the fluid (or air) gap between the magnetic poles, and still remain in direct communication with the fluid (or air).
In addition, fewer parts means the design is inherently more reliable and less expensive to manufacture than prior art devices.
See the SWAT Portfolio Lifecycle Chart.
| Balanced Diaphragm MicroSpeaker | The Balanced Diaphragm MicroSpeaker overcomes deficiencies of current designs by eliminating all of the individual elements comprising the sound producing diaphragm and the armature, and effectively integrating these components into a single “balanced diaphragm.” The result is a speaker that features the small size, efficiency, and power of Balanced Armature design with Voice Coil sound quality. |
SWAT Innovator
Dr. Roger Adelman has a diverse background in mechanical vibrations, acoustics, materials manufacturing, and biomedical engineering. He holds a BSME and MS in mechanical engineering from the University of Illinois, and a Ph.D. in mechanical engineering with studies under the Colleges of Engineering and of Medicine at the University of Cincinnati. He also holds an MBA from the same university. During his Ph.D. research, he realized that generalized signal processing was crucial to hearing aid efficacy, but was not being done in the industry, and so he dedicated himself to producing a poor man’s hearing aid.
At the University of Cincinnati in the early 70’s, he conducted some of the earliest work in hearing-related digital signal processing on HP-grant 1st-and 2nd-generation minicomputers that had dedicated FFT firmware for vibration analysis being pioneered at the University. Realizing that microminiaturization of DSP hardware would come in the future, he then directed his efforts toward the development of an ultra high efficiency broadband micro-speaker, capable of delivering any such prescriptive DSP-manipulated sound for modern hearing aids, including sounds in the deep bass range.
In 1992, he built empirically such speakers in both 6 and 8 mm diameters, and concluded that their micro-size (in which all activity was constrained in sub-wavelength geometries) required a new way to analyze sound. From 1995 onward he worked to analyze sound producing equipment using Sub-Wavelength Acoustic Technologies, i.e. modeling acoustics at the second order partial differential equation level.
Since 2006, Dr. Adelman continues to develop speaker technology, employing multiphysics finite element analysis methods for modeling his novel designs.