I've made the claim that we can drive a small speaker at a low frequency and feel it vibrating.

I've tried one set of Sony earbuds using my laptop to drive them and can't feel it at all. My laptop audio seems to have VERY poor low frequency response and these earbuds are really tiny. Perhaps a bigger on the ear type headphone will work better?

Kurtis revealed the secret. You have to drive the headphone with 2 tones spaced close together. They have little frequency response down low but a beat between (say) 200Hz and 240Hz tones is small but I can feel it.