Left: modulus (top) and phase (bottom) of the input impedance of the B♭-contrabass tuba with respect to frequency. Blue curve: measured impedance; dashed orange curve: modal fit function with N = 13 modes; green curve: error between measured and fitted impedances, defined by and arg(Z_fit) − arg(Z_exp) as regards the modulus and phase, respectively. Right: photograph of the experimental set-up for the measure of the input impedance of the B♭-contrabass tuba, displaying the device described in [35], here mounted on the tuba’s mouthpiece. (a) Input impedance as a function of frequency. (b) Experimental set-up.