Your voice is a vibration, and you can feel it when you place a hand on your throat when you speak. As long as there are molecules around, sound will be traveling though them by smacking into each other.

That’s why if you put an alarm clock inside a glass jar and remove the air, there’s no sound from the clock. There’s nothing to transfer the vibrational energy to – nothing to smack into to transfer the sound. It’s like trying to grab hold of fog – there’s nothing to hold on to.

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13 Responses to “Harmonicas”

  1. Sound waves do increase the temperature of the medium they travel through if they are absorbed by the medium. For example, therapeutic ultrasound uses this to heat-up skin tissues. From a loud speaker, you wouldn’t get any noticeable increase in temperature.

  2. Benjamin Jones says:

    So if sound is vibrating particles and heat is increased motion of particles why don’t I heat up in front of a speaker? Is there an increase in temperature where the sound waves travel?

  3. Jennifer Reynolds says:

    I made the harmonica, and my sister loved it.We had to make something and explain how to do it in Spanish, and she did it.

  4. Good question Finn! Particles can be attracted to each other, like the north and south pole of a magnet, or repel each other, like the south and south poles of a magnet, or be neutrally charged, like most things (a chair, a table, etc.) Air is usually neutrally charged, meaning that it’s doesn’t have a preference one way or the other. If you charge up the air (called ionizing) then the air will move one way or the other, depending on the charge of the object near by. And when air molecules crash, they really just bounce off each other like bouncy-balls, not like a car crash that leaves both cars wrecked and not looking like cars at all after the impact. Does that help?

  5. finnlachlan says:

    Why do air particles crash into each other instead of move away from each other so they won’t crash? Finn, 5 years old.

  6. Try a tongue-depressor size stick, like doctor’s use to look down your throat. 🙂

  7. Shiralee Seerden says:

    i do not know how to make it
    dose it need to be a big stick or a small stick

    samuel ;] ;/ ;[

  8. It’s usually because the paper didn’t lift the rubber band off the stick high enough. Try changing the spacing between the cuffs and see if this helps.

  9. Lorelei Grecian says:

    Boohoo my harmonica dosn’t work! 🙂 Mabey its because I used plain plosicle sticks.

  10. sevy keble says:

    It’s nice to make a harmonica when you don’t have a real one. 🙂

  11. Shannon Wade says:

    This harmonica didn’t work for me.

  12. Whoops – I’ll have our web guy upload a new version right away. Sorry about that! 🙂

  13. Michelle Vorlicek says:

    Hi Aurora,
    We don’t have sound with this video……any ideas?