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# Physics/physics of sound

Question
QUESTION: I know that sounds are vibratioss, eg. 440 vibration per second (440hz).
If I wanted to make the pitch a higher I could play 441hz. but could I play 440,5hz or is it impossible due to the fact that you can't have 0,5 vibrations per second?

ANSWER: Of course you can.  The second is an arbitrary human unit of time, there's nothing fundamental about vibrations that means you have to have so many whole vibrations in our human unit of a second.  440.5 Hz just means that you have 881 full vibrations in two seconds.  Similarly, you can have things at 38.79281476 Hz if you want...

---------- FOLLOW-UP ----------

QUESTION: Thanks. I should have thought of that!
Is there a maximum of vibrations per second that one can have or is it an infinite number?

That depends on the material you're talking about.  In a crystal lattice, there is a minimum wavelength (maximum frequency) to the sound...the shortest the wavelength of a phonon (yes, there's a phonon, just like a photon) can be is about twice the spacing between atoms in a crystal.  Other materials are a little messier...but basically that determines your fundamental highest frequency of vibration on the quantum level.

Physics

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#### Dr. Stephen O. Nelson

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