This is an extremely relevant sutta to your query, regarding perception and illness. below is a chanting of it and description from pirith.org.http://www.accesstoinsight.org/tipitaka ... .than.htmlhttp://pirith.org/download/girimananda.mp3
"The best Pirith Chanting I heard was by a small boy call Dhammaruwan, which is something special. The recording quality is poor, but I tried my best to filter it and make it of better quality.
Dhammaruwan Story :
Dhammaruwan was born in a small village near Kandy , Sri Lanka in November, 1968. From the age of about two, before he could read or write , he spontaneously started to chant the ancient Buddhist scriptures in the original pali language , known only to a few scholar monks.
Each day, somewhere around two o'clock in the morning, after sitting in meditation with his adopted and devoted Buddhist foster father for about twenty to forty minutes, he would spontaneously start to chant pali suttas. On the Poya or lunar Observance day, he would sometimes chant for two hours."
Dhammaruwan's foster father started making amateur recording of the chanting and invited prominent scholar monk to listen. The monk verified that it was indeed the ancient pali language and the boy were chanting it in an ancient style which no longer existed in world.http://www.accesstoinsight.org/tipitaka ... .than.html