Team develops speakers using artificial muscles vibrating at high speed
2020/08/21
- Research
Self-standing balloon or hemispherical-shaped device used for delivering omnidirectional sound
A research team led by Professor Naoki Hosoya of the Shibaura Institute of Technology’s College of Engineering has succeeded in developing speakers that produce sound by using artificial muscles vibrating at high speed. The speakers can deliver almost any sound in human hearing range omnidirectionally. A patent is pending for this technology (Patent application No. 2019-132812)
Key points
- Capable of delivering sound omnidirectionally
Creating new possibilities for stage design at concerts and other events - Materials themselves generate sound through vibrations
No restrictions on the shape of the speakers - Lightweight – just a few grams
The speakers can be installed in places or in conditions that were previously considered difficult
Point sound source needed for acoustic testing
The best way to check the acoustics at venues like concert halls is to carry out a test using a point sound source to measure reverberation time. Standard polyhedron-shaped, heavy speakers equipped with magnets and coils have traditionally been used in such tests. But when the speakers are relatively big for the sound field, they are not regarded as a point sound source.Quickly moving artificial muscles designed to move slowly to generate sound
To solve the problem, Hosoya’s team at the Department of Engineering Science and Mechanics successfully developed speakers with its spherical- or hemispherical-shaped dielectric elastomer actuator (DEA) vibrating to deliver sound omnidirectionally. The DEA is light, flexible and capable of generating major displacements. With these speakers, it is possible to create a point sound source regardless of the size of the sound field or speaker.
The DEA has a capacitor structure consisting of a polymeric dialectic film sandwiched between flexible electrodes. The electrodes are attracted to each other when a potential difference is applied, deforming the DEA by static electricity. The DEA has been gaining attention for creating artificial muscles that can be used in power-generation devices (energy harvesting) and in developing soft robots, for example. A dielectric elastomer has almost no volume change, with a Poisson’s ratio (the ratio of transverse contraction strain to longitudinal extension strain in the direction of stretching force) close to 0.5.
These speakers can omnidirectionally radiate sound up to 16kHZ – near the upper limit of human hearing. The team plans to accelerate research and development of speakers to provide sound that a wide range of people can easily hear.
The DEA has a capacitor structure consisting of a polymeric dialectic film sandwiched between flexible electrodes. The electrodes are attracted to each other when a potential difference is applied, deforming the DEA by static electricity. The DEA has been gaining attention for creating artificial muscles that can be used in power-generation devices (energy harvesting) and in developing soft robots, for example. A dielectric elastomer has almost no volume change, with a Poisson’s ratio (the ratio of transverse contraction strain to longitudinal extension strain in the direction of stretching force) close to 0.5.
These speakers can omnidirectionally radiate sound up to 16kHZ – near the upper limit of human hearing. The team plans to accelerate research and development of speakers to provide sound that a wide range of people can easily hear.
▲Spherical speaker made of acrylic rubber
▲ Hemispherical speaker made of silicon rubber
▲ How a balloon-shaped speaker vibratesClick here for an animated version of Figure 3
https://bit.ly/31b1rRg
https://bit.ly/31b1rRg
Article information
[Spherical speaker]Naoki Hosoya, Hiroaki Masuda (Graduated from SIT’s Department of Engineering Science and Mechanics in March 2016), Shingo Maeda (Associate Professor of Department of Engineering Science and Mechanics), “Balloon dielectric elastomer actuator speaker”, Applied Acoustics, Volume 148 (2019), pages 238-245, https://doi.org/10.1016/j.apacoust.2018.12.032
Contact
Planning and Public Relations Section
3-9-14 Shibaura, Minato-ku, Tokyo 108-8548, Japan (2F Shibaura campus)
TEL:+81-(0)3-6722-2900 / FAX:+81-(0)3-6722-2901
E-mail:koho@ow.shibaura-it.ac.jp