**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

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
*-	*-	*-	*-	*-	*-

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

**dynam, **spect, spect

• Pertinent description in the Humdrum User Guide
• Index to Humdrum Representations
• Index to Humdrum Commands
• Table for Contents for Humdrum User Guide