Demonstrations: Steam train -- Big band --Percussions -- Indian harp -- Country music -- Provence music -- Nightingales -- Organ and orchestra -- Harpsichord -- Baroque organ -- Choirs -- Ancient music -- Romantic organ. Tests: Locating of left and right channels ; Diaphony test -- Dynamics and noise -- Loud-speaker phasing -- White noise -- Pink noise -- Response curve of the equipment -- Colorations and resonances ; Equalizer adjustment ; Loud-speaker testing.