English Dictionary

The shift from pitch to stress appears to happen before the other obliques begin merging in the Proto-Italic, Proto-Germanic, Primitive Irish, and Middle Indo-Aryan. But further investigation into the timeline of sound changes […] shows that, at least in Germanic, the oblique and core noun stems sound quite unpredictably different in all these families by the time of the crucial accent shift from pitch to stress. […] once a language becomes stress-sensitive, there seems to be a strong tendency in early Indo-European languages to shift the stress to the first syllable. This change happens shortly after the change to stress accent in Proto-Germanic, Proto-Italic, and Proto-Celtic, and even Thessalian, with evidence from Dybo's Law and Verner's Law left behind to show that sound changes happened after the changes to stress accent.