diacoustic

The story

1. Proto-Indo-European*dwóh₁
2. Proto-Indo-European*trísinflu.
3. Proto-Indo-European*dwís
4. Ancient Greekδιά (diá)
5. Ancient Greekδῐᾰ- (dĭă-)
6. Englishdia-
7. Proto-Indo-European*h₂eḱ-
8. Proto-Indo-European*h₂ew-
9. Proto-Indo-European*h₂ṓws
10. Proto-Indo-European*h₂ḱh₂owsyéti
11. Proto-Hellenic*akóuhō
12. Ancient Greekἀκούω (akoúō)
13. Ancient Greekᾰ̓κουστῐκός (ăkoustĭkós)
14. Medieval Latinacousticus
15. Englishacoustic
16. English todaydiacoustic

From dia- + acoustic.