Or just do this at home(we did at work). No need to ruin a speaker. 1) Mix cornstarch with water in shallow plastic bowl. 2) Hold the bowl firmly against an of

Or just do this at home(we did at work). No need to ruin a speaker. 1) Mix cornstarch with water in shallow plastic bowl. 2) Hold the bowl firmly against an office-grade subwoofer 3) Turn bass+volume to max 4) Start experimenting with music (or noise generators of different frequencies) We had about 10 minutes of similar effects before the headache hit.