octives?

What physically is an octive? I mean there is the A note then there is the A note in the next octive. But why are they both A note? I understand it on paper but I do not understand it physically. Does it have something to do with frequencies?

if something is an octave above it it is exactly twice the frequency.

notice how at the 12th fret the distance between fret and bridge is double wat it is from neck to bridge. therefore it has half the wavelength. and therefore twice the frequency

sorry if thats a bit physical for u

um in terms of music each note in an octave have the smae role in music. they fit together.

i can go into the maths behind it but i dont know if thats helpfull :D

Originally Posted by: ics1974What physically is an octive?

Fret Spider gave a good answer. I want to give a few more specific details.

An octave is a musical interval between two notes (or more precisely, two pitche specific tones), one note of which is exactly double the frequency in Hertz (Hertz is a physical distance measurement of the wavelength of sound measured in cycles per second as it moves through the air).

Consider a note A that is defined by a sound at 220 Hertz. Another note that is defined by a sound at double that, 440 Hertz is an A one octave higher than the first A.

Exactly like Fret Spider mentioned, this is easy to see on a guitar because it is at the 12th fret, exactly half the length of the string. Great example!

Also of interest (at least to me :) ) is that research has indicated that the shape of the cochlea (the snail shaped part of the inner ear that functions as the "collector" of auditory data which it then sends it to the brain for processing) is the reason humans identify an octave as such. Research into acoustics and human hearing physiology has suggested that for example if our cochleas were a straight tube, we might have formed our musical alphabet differently. Possible with no repetition of letters. Or at least in a manner that would not place such emphasis on the octave.

i was toying with givin u guys the mathamatical argument, and i decided to.

if u have a fretted note the string vibrates between the fret and the bridge. but this vibration is not simple. it is made of many sets of waves which combine to make the sound of a guitar string. ever wondered why a note on a cello or piano etc sounds different. well its cos there are different waves within the wave that is the vibration of the string. the wavelength of each component vibration is the length of the vibrating string divided by an integer. ( whole number)

so the constituent waves have wavelengths the length of the string, half the length of the string a third of the length of the string. and these wavelengths correspond to different frequencies by an inverse relationship ( half the wavelenght double the frequncy). each wavelength vibrates different amounts, this gives different instruments there diferent tone.

in an octave all the frequencies (different wavelengths) in the higher of the two notes are present in that of the lower octave.

as the wavelength of the higher note is corresponds to the wavelength thats is half of the lower one etc and all the other ones match up.


so basicaly this is why octaves match so much cos all the sounds of the higher note is contained in that of the lower.


i realise this may go way over your head and it doesnt really matter but i felt someone might be interested.

Thanks for explaining this in such great detail. I always thought it was frequency but you guys just confirmed it. Had no idea it was double the frequency between octives though.

the first tone in the overtone series, if my memory serves me...and the 3rd is an octave above (the second is the 5th above the first octave).

;)
SarinaJ

Here is a page on the overtone series.

http://www.smu.edu/totw/overtone.htm