Humdrum Representation for Spectral Centroid

REPRESENTATION
**specC -- spectral centroid representation

DESCRIPTION

The **specC representation can be used to represent the frequency of the spectral centroid for pure or complex tones. Spectral centroid is the amplitude-weighted mean of several frequency components. For example, given three frequencies (200, 400, 900 Hz) of equal amplitude, the corresponding spectral centroid would be the arithmetic mean of the three frequencies (i.e. 750 Hz). For pure tones, the spectral centroid is equivalent to the frequency of the pure tone. For complex tones, the spectral centroid is higher when tones have greater energy (amplitudes) in the upper partials. Hence, spectral centroid provides a simple index for the richness or brightness of a tone or sonority.

Spectral centroid tokens are numerical values in units of hertz. Frequencies may be specified as integer or real values (using a decimal).

Barlines are represented using the "common system" for barlines -- see barlines.

FILE TYPE

It is recommended that files containing predominantly **specC data should be given names with the distinguishing `.spc' extension.

SIGNIFIERS

The following table summarizes the **specC mappings of signifiers and signifieds.
0-9frequency (in hertz) specified as an integer
or real value
rrest
=barline; == double barline
Summary of **specC Signifiers

EXAMPLES
A sample document is given below:
**specC**specC
*pure*complex
=1=1
19002730
868.9.
13624402
2263..
.3742
=2=2
rr
====
*-*-
Notice that frequencies can be either real or integer values. Rests are represented by the single letter `r'.

PERTINENT COMMANDS

The following Humdrum commands accept **specC encoded data as inputs:
centstranslates **specC to **cents
degtranslate **specC to **deg
degreetranslate **specC to **degree
freqtranslate **specC to **freq
kerntranslates **specC to **kern
pctranslate **specC pitch to **pc
pitchtranslates **specC to **pitch
semitstranslate **specC to numerical **semits
solfgtranslate **specC pitch to **solfg
speccchange numerical precision of **specC values
tonhtranslate **solfg pitch to **Tonh
The following Humdrum command produces **specC data as output:
specctranslates **freq, and **specC to **specC

TANDEM INTERPRETATIONS
The following tandem interpretations can be used in conjunction with **specC:
pure tones*pure
complex tones*complex
meter signatures*M6/8
key signatures*k[f#c#]
key*c#:
Tandem interpretations for **specC

SEE ALSO
barlines, **cents, **deg, **degree, **freq, **kern, **pc, **pitch, **semits, **solfg, **Tonh