high frequency

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun A radio frequency in the range between 3 and 30 megahertz.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun radio The frequency area from 3 MHz through 30 MHz, commonly used for radio broadcasting.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun 3 to 30 megahertz
• noun a pitch that is perceived as above other pitches