About: http://webisa.webdatacommons.org/431661797

Property	Value
http://www.w3.org/1999/02/22-rdf-syntax-ns#type	http://www.w3.org/ns/prov#Entity
http://www.w3.org/ns/prov#value	Some specific frequencies that are believed to be particularly useful are 20, 666, 670, 727 and 2127 Hz.
http://www.w3.org/ns/prov#wasQuotedFrom	freepatentsonline.com