If a tree falls in the woods and no one hears it does it make a sound?

This is a question about what is sound. Is it the compression and
rarefactions in the air or is it only a sound when it is heard?

This is also a question about mental health, distress and
psychopathology. If a person is in pain but shows no signs detectable by
a psychiatrist or other mental health professional (or I suppose doctor)
then are they suffering/mentally ill?

Or is mental health only about the external and what's detected by
common constructs of detection of mental illness, regardless of the
inner experience?