The Upanishads, Part 2 (SBE15), by Max Müller, [1879], at sacred-texts.com

NINTH BRÂHMANA.

1. Agni Vaisvânara, is the fire within man by which the food that is eaten is cooked, i.e. digested. Its noise is that which one hears, if one covers one's ears. When he is on the point of departing this life, he does not hear that noise.