Loudspeaker technology

SPL: Sound pressure level

The efficiency of sensitivity of a loudspeaker mounted in a baffle and a cabinet on 1 meter distance. A higher sensitivity means louder speaker. 

https://www.eminence.com/understanding-spl/

Speaker impedantie

https://mynewmicrophone.com/the-complete-guide-to-speaker-impedance-2ω-4ω-8ω-more/

https://mynewmicrophone.com/the-complete-guide-to-speaker-impedance-2ω-4ω-8ω-more/