The Facult¿ Polytechnique of Mons has participated in three programs of artificially triggered lightning in Saint-Privat d'Allier (France, 1986, 1990, and 1991). A close measurement (70 m) of the acoustic energy emitted by a lightning stroke permits an assessment of different electrical lightning parameters such as peak current, carried charge, and specific energy. Moreover, the spectral analysis of thunder confirms the cylindrical shock wave theory A. Few (1969, 1982) put forward a few years ago. The dominant frequency of the spectrum gives an estimate of the lightning channel energy per unit length. ¿American Geophysical Union 1994