When I clear the mind, I hear voices

Normally I don’t hear voices.
I feel they’re always in the background tho because I still talk to myself and interact with thoughts that are unrelated to what I’m doing
When I clear my mind, I hear them. When I wake up in the morning or on the onset of sleep and am super tired, I hear them

Does any one else experience this?
Why is it that slowing the mind makes me able to hear them!
It usually sounds like balloons popping, sirens, distorted or very quick speech