Subb: it's not that easy. When two exactly same frequencies sounds together, phase-difference comes into play. It may double the amplitude, but it may cancel the sound completely.
On guitar this never happens as the frequencies are always little different and also they always change a bit, so there is never good real match. And sound also comes not only from the string, but from the guitar body so the phases can't really exactly cancel.
On sub it too should not really cancel, but it may lower the amplitude significantly. Of course only in case the both props are EXACTLY at the same frequency. Which may be the case if they are propelled by the same engine. If they are not they will only have similar frequencies, and you would just see two lines (I guess) or one line a bit stronger, but far from twice.
Now if such props are synchronized or not, I don't know.
Btw. where does the second picture come from ?
Last edited by Dr.Sid; 12-03-08 at 06:39 PM.
|