system
Given the following post, respond as if you're commenting on Reddit:
human
What does true silence sound like?

I'm not sure about you guys and I'm no biology expert but even in "silence" I still hear a slight tone. Are humans unable to hear true silence? Is it just me?
gpt
Something similar comes up in the story of John Cage's inspiration for *4'33"*:

>In 1951, he visited an anechoic chamber at Harvard University in order to hear silence. "I literally expected to hear nothing," he said. Instead, he heard two sounds, one high and one low. He was told that the first was his nervous system and the other his blood circulating.