If a line of broad palisades, set edgewise in a line directed from
the ear, and at even distances from each other, be struck at the end
nearest the auditor, they will reflect the sound of the blow, and
produce a succession of echoes: these, from the equal distance of the
palisades, will reach the ear at equal intervals of time, and will,
therefore, produce the effect of a number of impulses originating in
one point. Thus, a musical note will be heard.