"...was the experiment constructed with very thin base material (12.6 mmstrong plywood). As shown in the picture, such a podest - in comparisonwith a rigid base - provides the measured capacity to produce a sound levelincrease ( in the auditorium) of about 3 dB in the vicinity of 50 Hz and about 5 dB by higher frequencies.Because hearing reacts very sensibly to scale variations in the lower frequencies,this sound level increase is very noticeable. Additionally, the psychologicaleffect on the performer should not be underestimated as he experiencesthe resonance of the base as 'resonance of the room..." [from: Jürgen Meyer, "Akustik und musikalische Aufführungspraxis",3., vollständig überarbeitete und erweiterte Auflage 1995,Verlag Erwin Bochinskiy, FFM]
In the image: Influence of a resonance producing podest on the tonediffusion of a double bass (after Askenfelt, 1986). An increase of 3 dBcorresponds to a doubling of the sound level. Strike-through line: rigidbase. Dotted line: resonance producing podest.