Seals do not have external ear flaps. Instead they have two small holes. However, seals do have ears and excellent hearing, which is even better under water. On land, sounds reach both ears simultaneously. This makes it possible for land mammals to localise where a sound is coming from. However, land mammals loose this ability under water, where sound waves do not enter through the ears but through the skull. Seals can localise the origins of all sounds under water thanks to their built-in, internal ears. Furthermore, seals are able to hear very high sound frequencies (up to 70.000Hz) Humans only hear frequencies up to 20.000Hz.