Sound archives and linguistic variation. The case of the Phlegraean diphtongs

Sound archives are important resources for sociophonetic analysis: first, they contain relatively uncontrolled speech styles, not usually included in the speech databases used in sociophonetic research; second, they allow us to study in a historical perspective some phonetic phenomena that would otherwise be known only for their most recent or contemporary manifestations. Several complex phonetic phenomena such as Romance diphthongization may be better understood by means of sound archives of spontaneous speech. The paper describes the general principles underlying the building of ADICA (Archivio dei dialetti campani), an archive of spoken dialectal texts from the Phlegraean area. The main features of Phlegraean diphthongs are thus discussed with particular attention to their variability, their social distribution, together with their historical development.