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Continued Drive Signal Development for the Carbon Nanotube Thermoacoustic Loudspeaker Using Techniques Derived from the Hearing Aid Industry
Technical Paper
2017-01-1895
ISSN: 0148-7191, e-ISSN: 2688-3627
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English
Abstract
Compared to moving coil loudspeakers, carbon nanotube (CNT) loudspeakers are extremely lightweight and are capable of creating sound over a broad frequency range (1 Hz to 100 kHz). The thermoacoustic effect that allows for this non-vibrating sound source is naturally inefficient and nonlinear. Signal processing techniques are one option that may help counteract these concerns. Previous studies have evaluated a hybrid efficiency metric, the ratio of the sound pressure level at a single point to the input electrical power. True efficiency is the ratio of output acoustic power to the input electrical power. True efficiency data are presented for two new drive signal processing techniques borrowed from the hearing aid industry. Spectral envelope decimation of an AC signal operates in the frequency domain (FCAC) and dynamic linear frequency compression of an AC signal operates in the time domain (TCAC). Each type of processing affects the true efficiency differently. Using a 72 Wrms input signal, the measured efficiencies in the frequency range from 100 Hz to 10 kHz were 1.01 - 1083 E-6 and 1.26 - 388 E-6 percent for FCAC and TCAC, respectively. In addition, the effects of these processing techniques relative to sound quality were evaluated in terms of total harmonic distortion (THD). It was shown that although the different signal processing techniques affected the true efficiency, none of them increased the efficiency of the CNT loudspeaker to the level of current moving coil loudspeakers. Additionally, THD as the only sound quality metric is incomplete because these processing methods can be optimized for pure tones but highly distort complex signals like speech and music. Therefore, a sound quality metric for complex signals is needed. Overall, CNT loudspeakers show promise for specific applications where weight savings and complex geometries are required.
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Citation
Bouman, T., Barnard, A., and Alexander, J., "Continued Drive Signal Development for the Carbon Nanotube Thermoacoustic Loudspeaker Using Techniques Derived from the Hearing Aid Industry," SAE Technical Paper 2017-01-1895, 2017, https://doi.org/10.4271/2017-01-1895.Data Sets - Support Documents
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References
- Aliev , A. , Lima , M. , Fang , S. , and Baughman , R. Underwater sound generation using carbon nanotube projectors Nano letters 10 7 2374 2380 2010 10.1021/nl100235n
- Braun , F. Notiz über Thermophonie Annalen der Physik 301 6 358 360 1898 10.1002/andp.18983010609
- Arnold , H. D. , and Crandall I. B. The loudspeaker as a precision source of sound Physical review 10 1 22 1917 10.1103/PhysRev.10.22
- Iijima , S. Helical microtubules of graphitic carbon Nature 354 6348 56 58 1991 10.1038/354056a0
- Yu , X. , Rajamani , R. , Stelson , K. A. , and Cui , T. Carbon nanotube-based transparent thin film acoustic actuators and sensors Sensors and Actuators A: Physical 132 2 626 631 2006 10.1016/j.sna.2006.02.045
- Xiao , L. , Zhuo C. , Chen F. , and Liang L. et al. Flexible, stretchable, transparent carbon nanotube thin film loudspeakers Nano letters 8 12 4539 4545 2008 10.1021/nl802750z
- Aliev , A. , Gartstein , Y. , and Baughman , R. Increasing the efficiency of thermoacoustic carbon nanotube sound projectors Nanotechnology 24 23 235501 2013 10.1088/0957-4484/24/23/235501
- Barnard , A. , Brungart , T. , McDevitt , T. , and Aliev , A. et al. Advancements toward a high-power, carbon nanotube, thin-film loudspeaker Noise Control Engineering Journal 62 5 360 367 2014 10.3397/1/376235
- Kozlov , M. , Haines , C. , Oh , J. , and Lima , M. et al. Sound of carbon nanotube assemblies Journal of Applied Physics 106 12 124311 2009 10.1063/1.3272691
- Barnard , A. , Jenkins , D. , Brungart , T. , and McDevitt , T. et al. Feasibility of a high-powered carbon nanotube thin-film loudspeaker The Journal of the Acoustical Society of America 134 3 EL276 EL281 2013 10.1121/1.4817261
- Barnard , A. , Brungart , T. , McDevitt , T. , and Jenkins , D. et al. Background and development of a high-powered carbon nanotube thin-film loudspeaker INTER-NOISE and NOISE-CON Congress and Conference Proceedings 2012 6 5617 5628 2012
- Barnard A. , Brungart T. , McDevitt T. , Jenkins D. & Kline B. Advancements toward a high powered carbon nanotube thin-film loudspeaker Proceedings of Noise-Con Denver, USA 2013
- Asadzadeh , S. , Moosavi , A. , Huynh C. , and Saleki O. Thermo acoustic study of carbon nanotubes in near and far field: Theory, simulation, and experiment Journal of Applied Physics 117 9 095101 2015 10.1063/1.4914049
- Tong , L. , Lim , C. , Lai , S. , and Li , Y. Gap separation effect on thermoacoustic wave generation by heated suspended CNT nano-thinfilm Applied Thermal Engineering 86 135 142 2015 10.1016/j.applthermaleng.2015.04.031
- Jia , P. , and Lim , C. Thermal-Acoustic Wave Generation and Propagation Using Suspended Carbon Nanotube Thin Film in Fluidic Environments Journal of Applied Mechanics 83 9 091007 2016 10.1115/1.4033893
- Xiao , L. , Liu , P. , Liu , L. , and Li , Q. et al. High frequency response of carbon nanotube thin film speaker in gases Journal of Applied Physics 110 8 084311 2011 10.1063/1.3651374
- Bouman , T. , Barnard , A. , and Asgarisabet , M. Experimental quantification of the true efficiency of carbon nanotube thin-film loudspeakers The Journal of the Acoustical Society of America 139 3 1353 1363 2016 10.1121/1.4944688
- Leibman , V. Frequency transposing hearing aid U.S. Patent No. 5,014,319 7 May 1991
- Alexander , J. , Kopun , J. , and Stelmachowicz , P. Effects of frequency compression and frequency transposition on fricative and affricate perception in listeners with normal hearing and mild to moderate hearing loss Ear and hearing 35 5 519 532 2013 10.1097/AUD.0000000000000040
- Aliev , A. , Mayo , N. , Jung de Andrade , M. , and Robles , O. et al. Alternative Nanostructures for Loudspeaker ACS nano 9 5 4743 4756 2015 10.1021/nn507117a
- Daschewski , M. , Kreutzbruck , M. , and Prager , J. Influence of thermodynamic properties of a thermo-acoustic emitter on the efficiency of thermal airborne ultrasound generation Ultrasonics 63 16 22 2015 10.1016/j.ultras.2015.06.008
- ANSI S12.54 Acoustics - Determination of sound power levels and sound power levels of noise sources using sound pressure - Engineering methods for an essentially free field over a reflecting plane American National Standards Institute New York 2011
- Bouman , T. DRIVE SIGNAL DEVELOPMENT FOR THE THERMOACOUSTIC LOUDSPEAKER Open Access Master's Report Michigan Technological University 2016