Reference tone
A reference tone is a pure tone corresponding to a known frequency, and produced at a stable sound pressure level (volume), usually by specialized equipment.
In media
[edit | edit source]The most common reference tone in audio engineering is a Audio file "1000Hz.ogg" not found at −20dB. It is meant to be used by audio engineers in order to adjust the playback equipment so that the accompanying media is at a comfortable volume for the audience. In video production, this tone is usually accompanied by a test card so the video programming may be calibrated as well. It is sometimes played in sequence between a 100 Hz and 10 kHz tone to ensure an accurate response from the equipment at varying audio frequencies. This is also the "bleep" tone commonly used to censor obscene or sensitive audio content.
In music
[edit | edit source]Many electronic tuners used by musicians emit a tone of 440Hz, corresponding to a pitch of A above Middle C (A4). More sophisticated tuners offer a choice of other reference pitches to account for differences in tuning. Some specialized tuners offer pitches used commonly on a particular instrument (standard guitar tuning, fifth intervals for string instruments, the open tones for various brass instruments).
In telecommunications
[edit | edit source]In telecommunication, a standard test tone is a pure tone with a standardized level generally used for level alignment of single links and of links in tandem.[1]
For standardized test signal levels and frequencies, see MIL-STD-188-100 for United States Department of Defense (DOD) use, and the Code of Federal Regulations Title 47, part 68 for other Government agencies.
References
[edit | edit source]- ^ Public Domain This article incorporates public domain material from Lua error in Module:Citation/CS1/Configuration at line 2172: attempt to index field '?' (a nil value). (in support of MIL-STD-188).
