In designing sirens, is the purpose of two tones to produce a "resultant"
tone"?
With two tones sounding simultaneously, their sound waves will add (reinforce) and subtract (cancel) at various frequencies.
For example: sounding an E-natural and a G-natural (a perfect minor third above), as in the 2t22, produces a resultant tone of C-natural (3 steps below the E natural)
Notes C + E-natural (a MAJOR third apart) produce a G-natural
(four steps below the C)
The same happens with organ pipes.
To produce very low pedal notes (which you may feel more than hear) without building the huge costly pipes necessary, organ builders will often create a "Resultant" stop, which sounds a note a fifth above the Unison note.
For example: if a C-natural pipe (produced by a 16 foot long pipe)
is sounded with a G-natural above (produced by a 10-2/3 foot pipe)
their resultant frequencies produce a low C @ 32' pitch length (an entire octave below the 16 foot C).
Has anyone made a dual-toned siren with notes a perfect fifth apart?
Such would synthesize a note a full OCTAVE below the lower of the two notes.
Since low tones carry farther, is the dual-toned siren made for that purpose?
In some siren recordings, I perceive the single resultant pitch more than the two actual tones creating it!
Thank you,