High Pitched sound in PIP sony 61" (1 Viewer)

I turned on my PIP and when I switched the audio to the small box, it has a high pitched noise associated with it.

The model is a 61" Sony KP61HS10. Wondering if all models do this. Best way to test is to use the same channel for both feeds. Only happens on the cable input.

Heres the weird part. My mom and her friend of age 50+ were unable to hear this sound, but both me and my sister early 20's, WERE able to. Can anyone else explain how we are able to hear a different frequency?

I am having about 20 people over for a gathering so I'm going to do a test to see if there is a corelation between age and hearing frequencies.

You were able to hear the sound while they weren't because your high frequency hearing is simply better than theirs. As you get older and damage your hearing more, the first thing you lose is the high pitch range. Same with people such as rock bands. Goes pretty fast.