Editing Ultrasound (section)

===Wireless communication===
Audio can be propagated by [[modulated ultrasound]].

A formerly popular consumer application of ultrasound was in television [[remote control]]s for adjusting volume and changing channels. Introduced by [[Zenith Electronics|Zenith]] in the late 1950s, the system used a hand-held remote control containing short rod resonators struck by small hammers, and a microphone on the set. Filters and detectors discriminated between the various operations. The principal advantages were that no battery was needed in the hand-held control box and, unlike [[radio waves]], the ultrasound was unlikely to affect neighboring sets. Ultrasound remained in use until displaced by infrared systems starting in the late 1980s.<ref>{{cite book | first = Jeremy G. | last = Butler | title = Television: Critical Methods and Applications | publisher = Routledge | date = 2006 | page = 276 | isbn = 978-0-8058-5415-2 }}</ref>

In July 2015, ''[[The Economist]]'' reported that researchers at the [[University of California, Berkeley]] have conducted ultrasound studies using [[graphene]] [[diaphragm (acoustics)|diaphragms]].  The thinness and low weight of graphene combined with its strength make it an effective material to use in ultrasound communications.  One suggested application of the technology would be underwater communications, where radio waves typically do not travel well.<ref name="economist1">{{cite news|date=2015-07-11|title=Acoustic chatter|url=https://www.economist.com/news/science-and-technology/21657353-graphene-may-usher-radios-do-not-use-radio-waves-acoustic-chatter|newspaper=The Economist|publisher=economist.com|archive-url=https://web.archive.org/web/20150724034441/http://www.economist.com/news/science-and-technology/21657353-graphene-may-usher-radios-do-not-use-radio-waves-acoustic-chatter|archive-date=2015-07-24|access-date=2015-07-23|url-status=live}}</ref>

Ultrasonic signals have been used in "audio beacons" for [[cross-device tracking]] of Internet users.<ref name=":15">{{cite book |doi=10.1109/EuroSP.2017.33 |chapter=Privacy Threats through Ultrasonic Side Channels on Mobile Devices |title=2017 IEEE European Symposium on Security and Privacy (EuroS&P) |date=2017 |pages=35–47 |isbn=978-1-5090-5762-7 | vauthors = Arp D, Quiring E, Wressnegger C, Rieck K }}</ref><ref>{{cite journal |last1=Mavroudis |first1=Vasilios |last2=Hao |first2=Shuang |last3=Fratantonio |first3=Yanick |last4=Maggi |first4=Federico |last5=Kruegel |first5=Christopher |last6=Vigna |first6=Giovanni |title=On the Privacy and Security of the Ultrasound Ecosystem |journal=Proceedings on Privacy Enhancing Technologies |date=April 2017 |volume=2017 |issue=2 |pages=95–112 |doi=10.1515/popets-2017-0018 }}</ref>