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A question of sound knowledge

Discussion in 'Electronic Basics' started by [email protected], Aug 17, 2004.

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  1. Guest

    A student adds a sound output feature to their design using a small
    sounder (about the size of your little finger) driven by a logic
    output from a microcontroller.

    The table of frequencies look like this:

    100 Hz
    200 Hz
    300 Hz
    400 Hz
    500 Hz
    600 Hz
    700 Hz
    800 Hz
    900 Hz
    1.0 kHz
    1.1 kHz
    1.2 kHz
    1.3 kHz
    1.4 kHz
    1.5 kHz
    1.6 kHz
    1.7 kHz
    1.8 kHz
    1.9 kHz
    2.0 kHz
    2.1 kHz
    2.2 kHz

    Why is this wasteful and partly senseless?

    Robin
     
  2. Rich Grise

    Rich Grise Guest

    Because nobody has any idea what you're talking about?
     
  3. Ban

    Ban Guest

    If you want useful sound, the frequencies should be logarithmically spaced
    like
    100Hz, 125Hz, 163Hz, 200Hz, 250Hz, 315Hz, 400Hz, 500Hz, 630Hz, 800Hz, 1k
    1k25, 1k63, 2k, 2k5, 3k15, 4k
    This will give the impression of equal rise throughout the range. It is easy
    to detect and will give satisfactory results.
     
  4. Ban

    Ban Guest

    I overread the size, that thingy wouldn't give any audible output at 100Hz
    unless you put it right next to the ear. Start with 500Hz or even higher and
    use closer spaced intervals.
    Your prof has the right approach, hope he doesn't flunk you. This world is a
    bit more than digital and a student should know basic physics and mechanics
    as well.
     
  5. etc.

    The upper frequencies in the range are going to be too hard to distinguish.
    For equal distinguishability, you want equal ratios (100, 200, 400...), not
    equal spacing.
     
  6. John Larkin

    John Larkin Guest

    If he/she drives it with a square wave it sure will.

    John
     
  7. Guest

    :) I hope you're wrong about that, but I fear not because something
    very similar to the above has been in a commercial product for the
    last ten years.

    Cheers
    Robin
     
  8. Guest

    ....and this is why no one has noticed the sillyness of it (in the
    commercial product that it lives in).

    It also consumes excessive code. The same audible effects can be
    produced a lot cheaper. [say five fundamentals? In geometric
    progression, at the "useable" higher frequencies].

    Robin
     
  9. Ban

    Ban Guest

    I fear it will then sound not much different with 300 or 500Hz, the latter
    being one of the recommended frequencies.
    The OP talks about a commercial product, what kind of commercial product is
    it and have you really measured the outputted frequencies? I cannot believe
    that there are used the stated frequencies.
     
  10. Jamie

    Jamie Guest

    touch tone dialing?
    i don't know.
     
  11. Guest

    That's what I say about MS Windows (as a former Acorn Archimedes user)
    "I don't believe it, why would anyone buy one of these?" but the Arch'
    is a commercial failure and the PC is a commercial success.

    Robin
     
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