An apparatus for producing a fingerprint signal from an audio signal
includes a means for calculating energy values for frequency bands of
segments of the audio signal which are successive in time, so as to
obtain, from the audio signal, a sequence of vectors of energy values, a
means for scaling the energy values to obtain a sequence of scaled
vectors, and a means for temporal filtering of the sequence of scaled
vectors to obtain a filtered sequence which represents the fingerprint,
or from which the fingerprint may be derived. Thus, a fingerprint is
produced which is robust against disturbances due to problems associated
with coding or with transmission channels, and which is especially suited
for mobile radio applications.