Decibels

REPRESENTATION

dB — relative amplitude representation

DESCRIPTION

The dB representation is used to represent relative amplitude in decibels. The reference amplitude is deemed to be 0 dB. In a group of tones, normally the loudest tone is selected as the reference. Typically this means that other tones have negative decibel values.

Relative amplitude values may be either integer or decimal values. Both positive and negative values are permissible.

FILE TYPE

It is recommended that files containing predominantly dB data should be given names with the distinguishing `.db' extension.

SIGNIFIERS

The following table summarizes the dB mappings of signifiers and signifieds.

0-9 decimal values + plus sign (optional) - minus sign . fractional second delimiter; null token —– —————————————–

Summary of dB Signifiers

EXAMPLES

The following sample document encodes the relative amplitudes for the first five harmonics of a tone pitched at middle C (C4). Notice the use of the *H tandem interpretations to indicate the harmonic number. In this example, all amplitudes have been given in decibels relative to the first harmonic.

**pitch **dB **dB **dB **dB **dB * *H01 *H02 *H03 *H04 *H05 C4 0.0 -5.3 -24.3 -5.3 -23.7 *- *- *- *- *- *- ———– ——– ——– ——– ——– ——–

PERTINENT COMMANDS

The following Humdrum command accepts dB encoded data as input:

spect convert notated sonority to instantaneous spectrum – ————————————- —————————————————-

TANDEM INTERPRETATIONS

The following tandem interpretations can be used in conjunction with **dB:

MIDI channel *Ch1 harmonic number *H3 meter signatures *M6/8 —————— ———

Tandem interpretations for dB