When a tree falls, it creates 'shock waves', 'standing pressure waves'.
These pressure waves are absolutely silent.
They must impinge on an eardrum, set it in motion. This motion, is chemo-electrically neurologically to the brain. The brain then compares these audio-vibratory impressions to a list of reference 'vibrations, sorts according to environment, social, experiential, memory, etc... and finally presents all the evidence as a 'concept'. This 'concept' is the 'sound' that we hear, a hologramic construct in Mind.
In front of your nose, despite long refuted 'naive realism's' insistance, there is absolute silence.
(Do you think that there is actually 'light' and 'color' 'out there'? Really?)
The tree makes no 'sound' (unless you define 'sound' as; 'standing pressure waves as interpreted in/by the mind of the hearer') if no ear is there to 'hear'.
The tree does not fall if there's no eye to see!
The tree does not even exist, if there is no mind to conceive/perceive.