Rat's pointless science questions - Part the Third

[Rat]

I was playing my melodica recently, and it got me thinking. For those who don't know, it's basically a wind-powered (i.e. breath-powered) keyboard. As the name suggests, it's really for melodies, and is therefore most suited to single notes. If you play more than one note, the air is thus shared amongst them, and each is quieter than if you played it alone. This got me wondering about a few things.

Should the total volume of sound (in decibels) be the same for two notes as for one? Is the volume of each note half of what it would be alone, or does the logarithmic decibel scale alter this? If it is half, would I then have to add another two notes to halve it again?

No particular reason for asking; I just thought that if anyone knew, it would be someone here.

Cheers,
Rat.

 

[wahrheit]

The melodica is a mechanical piece, I don't think you can apply logic like 2 notes played equals half the volume.

Those melodicas need a certain amount of breath to produce full, rich sound and volume. Beyond a certain threshold, there won't be any sound produced at all. Therefore I guess, without being the scientist here, that your answer can not really be addressed in a purely scientific, mathematical way. (Yes! Wild guesswork here.)

 

[Rat]

You're certainly right in that I should have stated a constant pressure of air going in, and all similar quantities being equal. It should also be noted that there is no perceptible difference in ease of breathing into the mouth piece as the number of notes changes; I know this, because I just tried.

 

[grayman]

When I saw the title to this thread I thought that the Pope had issued another statement...sorry.

 

[Dragonrock]

I think you should never eat popcorn and play the melodica as they are very hard to clean.

 

[fishbait]

I play a similiar instrument called s Shruti box. The Shruti is made in India, is about the size of a laptop computer, and air is supplied by squeezing and releasing a bellows. It is used during meditation to produce pure single tones but chords of 3 or 4 notes can be played.

I suspect your question involves more than simple math given that each note has a specific reed that is unique in mass and stiffness. A lower note reed is heavier or stiffer than a higher one and requires more air pressure to get it to vibrate. Another variable is the amount of sustained back-pressure that is necessary for all wind instruments.

Try playing two adjacent notes, an A and a B, say, and note the amount of effort needed; then try an A and a G and see if the blowing effort changes.

It's a mechanical device that operates on know principles of sound physics and fluid dynamics, so the math could be worked out if you knew all the variables. Beyond that, I dunno. Interesting question, though.