“Sonate” (Sondages acoustiques pour l’évaluation de la qualité d’images des téléscopes) – Acoustic sounding to estimate the quality of telescope images – is a prime example of professional/amateur collaboration as it involved 3 professionals and 22 amateurs, who, in order to collect the maximum amount of data, relayed one another in 10-day shifts over a period of 4 months in 1984, using the 1-m telescope at the Pic du Midi. A preliminary campaign with the 2-m telescope in 1982 had shown that the profile of sound waves reflected from the layers above a site could be correlated with the quality of telescopic images at the same site.