MODULA'TION, noun [Latin modulatio.]
1. The act of forming any thing to a certain proportion; as the different proportion and modulation of matter.
2. The act of inflecting the voice in reading or speaking; a rising or falling of the voice.
3. In music, the art of composing melody or harmony agreeable to the laws prescribed by any particular key, or of changing the key, or of passing from one key to another.
Modulation is the manner of ascertaining and managing the modes; or more generally, the art of conducting the harmony and air through several modes in a manner agreeable to the ear and conformed to rules.
4. Sound modulated; melody.