By Nathan Towery
A lot of speaker designs in the world yield powerful, high-quality sound but fail to deliver when the speaker is miniaturized. This is because no one has figured out the physics behind doing so — until now. University of Mississippi alumna Maryam Landi (MS 17) has developed a new structure that emits sound waves from miniature speakers more efficiently, especially when it comes to low frequency, or bass.
Small sound sources are unable to emit sufficient quality sound power at low frequencies. Traditionally, adding woofers to speaker drivers has mitigated this problem. However, with the growing trend in miniaturizing electronic devices, it is important to achieve an efficient emission while keeping the device as small as possible.
Landi has proposed enclosing a miniature sound source by 3-D printing a miniature meta-cavity for acoustic resonant emission enhancement. The cavity enhances low-frequency emission more than 200 times (sound power), which has been confirmed by both modeling and experiments.
UM collaborators on the project include Likun Zhang, assistant professor of physics and astronomy and Landi’s graduate adviser, and Wayne Prather, senior scientist at the National Center for Physical Acoustics. Ying Wu and Jiajun Zhao, of King Abdullah University of Science and Technology, also contributed to the project.
“Through the resonance of the air inside the channels, a lot more of the electric power of the source is converted to sound power than would otherwise be the case,” Wu said.
The design follows from reducing the effective sound speed in the meta-cavity, thereby reducing the resonant frequency. The resonance-based emission enhancement is found to have an analog with enhancement of spontaneous emission from an atom by a quantum cavity.
The significant enhancement by the acoustic cavity will enable the design of a new generation of high-performance miniature speakers. Landi and her collaborators potentially have changed the face of miniature speakers, as we know it.
Zhang said he is “very grateful to have worked on the project and be a mentor to Maryam.”
In addition to publishing her work in the prestigious journal Physical Review Letters, Landi, upon graduation in 2017, obtained a position as research assistant intern at the Department of Communication Sciences and Disorders’ Hearing and Language Lab at Northwestern University in Evanston, Illinois.
To read the published article, please visit: https://journals-aps-org.umiss.idm.oclc.org/prl/abstract/10.1103/PhysRevLett.120.114301