Prosodia Rationalis

Prosodia Rationalis is the short title of the 1779 expanded second edition of Joshua Steele's An Essay Towards Establishing the Melody and Measure of Speech, to be Expressed and Perpetuated by Peculiar Symbols, originally published in 1775.

The treatise is notable as one of the earliest works in the subject and its insight that in speech, unlike in most music, pitches slide rather than exhibit distinct tones held for lengths of time.

... Now I appeal to them, whether they can perceive any difference of tone betwixt the accented and unaccented syllable of any word?

[7] But as each section of Steele's argument was completed, he sent it off for Lord Monboddo's comments, which were then incorporated along with Steele's replies in subsequent sections of the book: "consequently, Prosodia Rationalis is, in effect, an extended dialogue between the two men, to which is appended, in the second edition, an additional series of questions from other hands, together with the author's replies.

"[8] Steele proposed that the "melody and measure" of speech could be analyzed and recorded by notating five distinct types of characteristics, the "five orders of accidents".