A device for indicating at least a first vibration level VIB1 derived from
a first acceleration signal .gamma.1 includes: first analysis element
FT1 for resolving the first acceleration signal .gamma.1 into a plurality
of axial analysis signals .gamma.1.sub.i each occupying an identified
frequency band B.sub.i; a first memory RM1 having recorded therein a
plurality of axial weighting coefficients KA.sub.i, each corresponding to
one of the identified frequency bands B.sub.i; and a first control
circuit CC for summing the p.sup.th powers of the axial analysis signals
.gamma.1.sub.i weighted by the axial weighting coefficients KA.sub.i,
thereby producing the first vibration level VIB1.