All about T/S parameters, AKA Thiele Small Speaker Measurements - Cutting Through the Confusion!
http://www.home-speaker.net/thiele-smal ... ments.html
T/S or Thiele/Small, what does It mean?
"Thiele/Small" commonly refers to a set of electromechanical parameters that define how a loudspeaker driver performs. They are useful when designing speakers because they are more easily determined experimentally than more fundamental mechanical parameters.
They are named after A. N. Thiele of the Australian Broadcasting Commission, and Richard H. Small of the University of Sydney, who pioneered this line of analysis for loudspeakers.