I just saw a post about a 40" bass. The person mentioned 'an octave below a conventional 4 string bass. Can an audience actually hear that bottom note? My experience with super low frequencies was mainly with a giant custom built p.a. which had 4 JBL loaded subs. The keyboard player using an Arp Odyssey synth opened a particular song (Riding the storm out) with the synth inaudibly low and using the coarse pitch slider he slowly raised the pitch. At first there was normal noise and conversation in the typically packed club. But the when the sound began to make the room throb (drinks actually began to 'walk' across the tables due to vibration) people stopped conversing and looked disoriented as the sound rose in audibility. For a few seconds their faces flashed everything from fear/slight panic to huge grins prompted by the sonic massage. Where does it cease to be musical and become Cerwin Vega's Earthquake effect?