Assuming that  we don't have an anechoic chamber, in order to perform the acoustic measures we will use the semi reverberant technique; clearly we will try to use a big room with the speaker in the center of it, in order to have all the reflecting walls as far as possible. The measurement happens in three stages: the first is the near field, that takes care of the low frequencies and is made possible placing the mic very close to driver so that diffractions and room effects are negligible. The second phase is the far field, where the microphone is placed to approximately one meter from the loudspeaker and, using the gating technique, only the frequency range free of reflections is used. Finally the third phase joins the two responses, near field and far field, to get the total driver response. The hardware needed for the acoustic measurement is different from the one used in the impedance measurement:  we will need  a microphone with his  pre-amplifier,  an amplifier and some meters of cable. Let's go directly to the cables!