TRAVERSAL TIME OF ACOUSTIC PLATE WAVES THROUGH A TUNNELING SECTION

Experimental evidence is given for the unnoticeable time delay undergo ne by an acoustic Lamb wave pulse in penetrating a forbidden barrier, represented by a narrowed plate region in the propagation path. Measur ements, which use a technique unique to Lamb waves overcoming typical objections made in wave packet experiments, have been performed in var ious aluminium plates far several frequencies and different barrier le ngths and show a value of the traversal time close to zero that appear s to be independent from the barrier length.