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What frequency is a dog whistle and a tv at?

  1. Mar 1, 2005 #1

    As the title says: what frequence does a dog whistle operate at (since I can hear them it'd be nice to know) and a tv (CRC) that's turned on? I'm not sure all TVs have this sound, but at least my tv has =) - it's a panasonic - does anyone know what frequency, because that's one of the reasons I never have the TV on - it keeps sending out this annoying tone which is really high pitched and is really annoying. (a bit higher pitch than when you get out of a really loud disco)...

    Can frequency meters be bought to check it for myself?

  2. jcsd
  3. Mar 1, 2005 #2
    Take a sound recording on your computer and analyse the wave file using Spectrogram or Spectrum Laboratory (availible freely online I think).

    A prominant frequecy should be observed above 20 000 Hz, if this sound frequency is well defined (which it should be if you can hear it) it should stick out well on the frequency spectrum.
  4. Mar 1, 2005 #3
    The horizontal deflection frequency of an American (NTSC) tv is 15750 Hz, within the hearing range of good human ears. In my younger days I could hear it clearly in most tv's. Sounds like a ringing hiss of sorts because it is rich in harmonics.
  5. Mar 2, 2005 #4
    I tried recording the sound with my headset - didn't work out too good - lots of disturbance... But Kevin - I'm sure it's the same sound we have here - we use PAL instead (Sweden)... I'll try to google on it. Thanks for the help guys, and it would be nice if someone found out the real frequencies or the dog whistle and the tv..
  6. Mar 2, 2005 #5
  7. Mar 2, 2005 #6
  8. Mar 2, 2005 #7
    Is there a way to artificially create these sounds on the computer? (I mean something that's free now...)
  9. Mar 2, 2005 #8
    Yeah, it's almost certainly the horizontal frequency of the tv, whatever that is for your system. It usually comes from magnetorestriction vibration of the "flyback" core, Tends to be worse in older sets, things tend to loosen up mechanically with time.

    You ever hear the old technician's joke about what NTSC and PAL stand for?

    NTSC Never The Same Color
    PAL People Are Lavender

    Last edited: Mar 2, 2005
  10. Mar 2, 2005 #9


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    There's really no way to record extremely high-frequency sound on a normal computer system with a normal consumer sound card. The highest sampling frequency you'll likely get with a consumer sound card is 44 kHz. At that sampling frequency, the highest frequency that you can actually sample is 22 kHz. Most cards probably also have analog filters to limit high frequency noise from being aliased back to lower frequencies.

    If the sound is 15 kHz, you will probably be able to pick it up on a computer, though.

    - Warren
  11. Mar 2, 2005 #10
  12. Mar 2, 2005 #11


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    I didn't know dogs could whistle.
  13. Mar 2, 2005 #12
    I think that article is a little off. Almost anyone with reasonable hearing could hear the low end of the stated range and the majority of the population could likely hear 12.4 kHz. Hearing does roll off rapidly in the vicinity of 10 kHz and there is a _lot_ of variability between individuals. Also, at the high end of an individual's range it's not so much "hearing" as "sensing". But it is there. That's why cd audio has a 20 kHz bandwidth.
  14. Mar 2, 2005 #13
    Try that:

    and click on sound - I really think it has a low frequency - nothing in the vincinity of the TV sound... Sounds more like some kind of a kettle of hot water boiling... And sensing? I mean... we have no membrane on the outside of our body to be able to sense waves that come in such rapid speed - such high frequency, other than the ears - do we? (And the oppisite of low frequencies at like 50 Hz, where you can sense them with the body)
    Sorry for my temporarily bad english, kinda late..
  15. Mar 2, 2005 #14
    Maybe I've remembered the wrong figures, but I thought the human hearing thresholds were 20Hz - 20kHz?

    Which means dog whistles, which are "inaudible to humans"(ultrasonic) should be above 20kHz?
  16. Mar 2, 2005 #15
    I could have perhaps been more clear. I meant sensed as in a discomfort or unpleasantness in the ears.

    As I stated previously, the high end is highly variable between individuals. 20 kHz is accepted as the limit for the majority of people which is why that is the standard for high quality audio.

    Yes, the lower end for hearing is 20 or so. That also varies individually. Although there is the perception of vibration in the body. As I recall when the movie "Earthquake" came out way back when they rigged some theaters with a special sound system that used infrasonics. Marketting gimic.

    Another important frequency for hearting is in the range of 100 to 200 Hz. Below that point you have no perception of direction. This is why subwoofer systems were developed.
  17. Mar 4, 2005 #16
    Hehe, good to know, didn't know that the De Haas effect didn't work under the 100-200 range. I saw a couple of headphones (is that what you call them?) today in a store with a range from 10-24k Hz.

    Do you know any way to test my hearing? It'd be fun to know my hearing limit.
    So ultra- is high and infra- i low frequencies?
  18. Mar 4, 2005 #17
    hmmm, so that explains why i can tell if a TV is turned whether it is muted or not. i knew i never could really "hear it" per se, but i could always "sense it" i suppose a normal TV's pitch is close to my hearing limit. interesting.
  19. Mar 4, 2005 #18
    I found yet another, even more high pitched frequency that I can hear... (of course, there is no way for you to verify that I hear it... Although you might analyze the video)
    The first video - a quite high frequency, with a quite low amplitude. It sounds like ... well... nothing I've ever heard before... just like a really high pitched sound in the background of his talking. (the first video with the moving blob that shows round wave movements)

    I just watched the movie with windows media player and there there is no high frequency, it seems more compressed than the real player one.
    Last edited: Mar 4, 2005
  20. Feb 13, 2008 #19
    hypnotic whistling

    I also have a panasonic television which whistles, it is about 8 years old.

    I came across this thread in a google search on the subject of television whistle, i have detected it before in other sets.

    I wonder: Does the high-pitch whistle (barely consciously detectable) enhance the persuasive hypnotic effect of the information ingested while watching television?
  21. Feb 13, 2008 #20


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    NTSC - Never The Same Color
    SECAM - System Entirely Contrary to American Method
    PAL - Perfection At Last

    Don't be silly MUST_WATCH_FOX, there isn's any hypnotic MUST_WATCH_FOX effect.
    Last edited: Feb 13, 2008
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