Just a few minutes ago, our TV had an emergency weather alert. It took a few seconds to load up and I used that time to mute it before it started that terrible noise. Nonetheless, my toddler put his hands over his ears and gave an intermittent moan for the entire time, even though it was muted and I couldn’t hear anything. Is there any possibility the TV could make some high-frequency noise during an emergency broadcast that isn’t audible to adult ears, but somehow bypasses the mute button?
The only other possibility I can think of is another TV in the house (our basement tenants, or my wife upstairs) was making the same emergency broadcast without being muted, and some high frequency noise is loud enough to bother my toddler even through the floor/ceiling.
“The tone is 1050 Hz (help·info) on a NOAA Weather Radio station. On commercial broadcast stations, a “two-tone” attention signal of 853 Hz and 960 Hz sine waves is used instead, the same signal used by the older Emergency Broadcast System.”
Well, 1050 Hz is well within the range of normal adult hearing. Most adults can’t hear in the range of 14000 Hz and above. But it is possible that some component inside the TV is making a resonate high frequency noise related to the signal that is being broadcast. You could download one of several sound meters available for your phone and test it.
I just played the test signal on my phone and my cat did not like it. Not howling and screeching, but definitly annoyed.
Also I must add, that Nissan corrected the issue in their radio in the link above.
My high-frequency hearing is still good, and when my TV is on mute in a quiet room I can hear a slight high-pitched buzz when there’s a picture that is louder the brighter the picture is (when the picture goes black between scenes or whatever the buzz momentarily stops).
You definitely do lose the higher frequencies as you get older, though. I’ve heard of some shopkeepers who used speakers to broadcast high frequency sound outside their store to discourage young people from loitering around outside, that older people won’t hear.
Incidentally, I was listening to a recent ‘Conan O’Brien Needs a Friend’ podcast episode where a technical assistant did a high-frequency hearing test on Conan, assistant Sona Movsesian and producer Matt Gourley. Interestingly, all three of them and I all stopped hearing at the same frequency (about 16,000 Mhz), even though we’re all different ages. When they ran the test again with the volume up a little more, this time Matt, Sona and I heard one step above Conan, which was at about 17,000 Mhz I believe (the upper end of perfect younger human hearing is around 20,000 Mhz).
I don’t know what’s displayed on screen during such a warning, but if it looks very blocky with bright colours like something from the 1980s, it’s possible that your modern HD TV is having a hard time rendering it and that its seldom-used SD-to-HD circuit is giving off a high-frequency noise only your toddler can hear. So it wouldn’t be the soundtrack, but the TV itself whining.