Abstract: The method makes possible the determination of loudspeaker parameters in real operation through a measurement of the moving-coil current im and it contains the following steps:

Abstract: A wave digital filter comprising at least one filter section without delay elements, each port thereof having a positive port admittance, and the signal quantities therein being operated upon, preferably within certain individual multiport adaptors of the filter section, in such a way that the pseudo power, ##EQU1## RECEIVED BY RESPECTIVE ADAPTOR PORTS V OF PORT ADMITTANCE G.sub.v and associated with input quantities a.sub.v (t.sub.m) and output quantities b.sub.v (t.sub.m) at respective operating times t.sub.m, is equal to or preferably only slightly greater than the value of the pseudo power function p (t.sub.m) which is obtained by omitting rounding or truncating, respectively, or overflow of the numbers being processed, and instead carrying out arithmetic operations precisely.