It&#x27;s perhaps not the perfect metaphor.  But up till now all we have really directly observed from outside[1] our solar system are electromagnetic waves(of various wavelengths including visible light), and this is something quite different.<p><a href="http:&#x2F;&#x2F;gmunu.mit.edu&#x2F;sounds&#x2F;sounds.html" rel="nofollow">http:&#x2F;&#x2F;gmunu.mit.edu&#x2F;sounds&#x2F;sounds.html</a> has a bit more info on why scientists tend to use the sound analogy when talking about gravitational waves.<p>[1] Maybe not entirely true, we have convincing evidence of some extra-solar dust reaching earth too..