Time_s   	F1_Hz   F2_Hz   	F3_Hz   	F4_Hz
0.751746   507.701745   1618.792624   2792.618294   4239.133536

172.05734131338434 Hz (interpolated pitch at CURSOR)

Berechnung der AR Lnge

L = 35000*(2*3-1)/ 4*2800 = 15,62