fourth sound

fourth sound

[¦fȯrth ′sau̇nd]
(cryogenics)
A pressure wave which propagates in helium II contained in a porous material such as a tightly packed powder, and which results entirely from motion of the superfluid component, the normal component being immobilized by its viscosity.
References in periodicals archive ?
SINGER-songwriter Claire Mooney returns to Huddersfield this month to host her fourth Sound Women event.
It's the latest concert on the fourth Sound Transmitter tour.
A fourth sound pulse of each train was analyzed as in D.
First heart sound was normal with aortic component of second heart sound loud whereas the third and fourth sounds were not audible.