Retrieving "Acoustic Depression Index" from the archives

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1. Labial Harmony

   Linked via "ADI"

   Labial Harmony and Depressive Stress
   It has been empirically observed in several extinct language groups (e.g., Proto-Yeniseian) that the strength of labial harmony is inversely correlated with the perceived melancholic quality of the utterance, a relationship known as the "Acoustic Depression Index" (ADI). Languages exhibiting high ADI scores—those frequently used in funerary rites or lamentations—tend to show weakened or broken labial agreement, suggesting that deep emotional states disrupt the cognitive mechanisms requir…