Pitches in **kern are encoded as equally-tempered values at concert pitch. Kern is not able to represent pitch deviations from equal temperament. Diatonic pitch names are encoded using the letters A to G. Octaves are indicated by a system of upper- and lower-case letters, and by letter repetition. Middle C is represented by the single lower-case letter `c'. The C an octave above is represented by two lower-case letters: `cc' -- with each successive octave adding another letter. The C an octave below middle C is represented by a single upper-case `C'. The C an octave lower yet is represented by two upper-case letters: `CC' -- and so forth. Changes of octave are deemed to occur between the pitches B and C. Thus the B below middle `c' is rendered as a single upper-case `B'; the B below `cc' is `b' and so forth. Sharps are indicated by the octothorpe sign (#) whereas flats are indicated by the minus sign (-).

The kern command is able to translate any of the pitch-related representations listed below. In each case, a tuning standard of A4 equals 440 hertz is assumed. For descriptions of the various input representations (including **kern) refer to Section 2 (Representation Reference) of this reference manual.

**cents	hundredths of a semitone with respect to middle C=0
**degree	scale degree including octave designation
**freq	frequency in hertz (abbreviated Hz.)
**fret	fretted-instrument pitch tablature
**MIDI	Music Instrument Digital Interface key-press tablature
**pitch	American National Standards Institute pitch notation (e.g. "A#4")
**semits	equal-tempered semitones with respect to middle C=0
**solfg	French solfège system (fixed `doh')
**specC	spectral centroid (in hertz)
**Tonh	German pitch system

For numerically-oriented inputs, such as **cents, **freq, **MIDI, **semits, and **specC, variant enharmonic spellings are selected for output according to the prevailing key signature or explicit key indication. (Refer to key and key signatures in Section 3 (Humdrum Tandem Interpretations). Hence, in the key of G minor, F-sharp and E-flat spellings will be output rather than G-flat and D-sharp. Kern recognizes the presence of key, or key signature tandem interpretations. If no key or key signature is encountered in the input, a default key of C major is assumed. Kern is sensitive to both pitch-class and pitch-height key signatures. In the case of pitch-height key signatures, the user can specify complex spelling preferences, such as F#2 rather than Gb2, but Gb3 rather than F#3, etc. See SAMPLE OUTPUT below.

It is recommended that output files produced using the kern command should be given names with the distinguishing `.krn' extension.

-h	displays a help screen summarizing the command syntax
-x	suppresses printing of non-pitch-related signifiers

In the default operation, kern outputs any non-pitch-related signifiers in addition to the kern value. For example, the **pitch token "A6zzz" will result in the output "aaazzz" -- that is, after translating A6 to "aaa", the "zzz" signifiers are retained in the output. For some applications, echoing non-pitch-related signifiers in the output is useful. However, in other situations, the result can prove confusing -- especially, when the non-pitch-related signifiers are upper- or lower-case letters from A-G. Consider the case of the **freq token "aA#5"; after translating "A#5" to "aa", the leading non-pitch-related signifier "a" will be prepended to the output, hence the value "aaa" -- which will undoubtedly cause confusion. The -x option is useful for eliminating non-pitch-related signifiers from the output. For most inputs, the -x option is recommended.

• Introductory description in the Humdrum User Guide
• Advanced description in the Humdrum User Guide
• Index to Humdrum Commands
• Table for Contents for Humdrum User Guide