What is "barytonesis"

In phonology, barytonesis, or recessive accent, is the shift of accent from the last or following syllable on any non-final or preceding syllable of the stem, as in John Donne's poetic line: but éxtreme sense hath made them desperate, the Balto-Slavic Pedersen's law and Aeolic Greek barytonesis. The opposite, the accent shift to the last syllable is called oxytonesis.