Acoustic labyrinth

Acoustic labyrinth is a special loudspeaker baffle arrangement popular in the 1950's used to prevent cavity resonance and to reinforce bass response. The arrangement entailed the rear of the woofer cone being coupled to a folded duct between 6 to 8 feet long. The duct is is lined with sound absorbing material hence inhibiting resonance and absorbing energy from the back of the cone.