Perception

There is an old Tamil song which says that all we see is not true and all we hear are lies. In
modern terms what we see nay all that we see ,hear ,smell taste and feel are not really what we think we see etc. Think is the operative word.The human ear has evolved over millions of years and at at present capable of sensing a small portion of the total spectrum. Any frequency which falls out side this is not sensed by the ear. I must say human ear. There are other animals ,dogs for instance , which are capable of hearing higher pitch sounds.
The ear is just a sensor albeit a complex one. A spoken. A cry could be one of fear,ecstasy ,disgust or alarm. The human brain takes the sound waves and is able interpret and understand not only the words but also the feelings.  However another element creeps into equation. This is the cognitive bias that each person has. These are unique to each person and is the result of each person's nurturing and conditioning. Once this is involved what you hear is no more the real sound and emotion. It becomes our subjective perception. This is true of all our sensory inputs.
All that glitters is not gold. Whatever we think we see or hear is just a construct of our brain. (May be that is why the scriptures call everything in the causal universe as MAYA or illusion.) It is our subjective perception and even to us is not constant but changing with time and circumstances.