Don Gilmore
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- Nov 22, 2019
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Gentlemen:
I'm working on a device which involves shifting a harmonic partial on top of another one and I need to know how to determine the acoustic sum of the resulting two unison sine waves. I realize that the sum of two waves in phase has twice the amplitude and, if 180 deg. out-of-phase, interfere for an amplitude of zero, but I'm talking about actual volume in air. When two unison tones sound simultaneously the result is louder, but not twice as loud. I would think that it would be the RMS sum of the two separate RMS values of the waves, but does wave phase also come into play? It seems to me that it would, yet that would indicate that two given tones would have a random combined volume, depending on their phase difference.
Here is what I'm trying to do. I have two separate sine waves that are close together. One is at the correct frequency and one needs to be corrected and added to the other. Lets say the correct one is 100 Hz and the other one is 101 Hz. Rather than try to correct (shift frequency) and remix the bad tone, I'd like to determine its volume and increase the correct one by this amount to simulate the equivalent.
So, for example, if the 100-Hz tone is at 70 dB and the 101-Hz tone is at 62 dB, I want the equivalent of what the total volume would be if both tones were at 100 Hz. Then I would amplify the 100-Hz tone to this value and discard the 101-Hz tone in the output.
Incidentally, this is an analog circuit, not DSP. Thanks for any replies.
Don
I'm working on a device which involves shifting a harmonic partial on top of another one and I need to know how to determine the acoustic sum of the resulting two unison sine waves. I realize that the sum of two waves in phase has twice the amplitude and, if 180 deg. out-of-phase, interfere for an amplitude of zero, but I'm talking about actual volume in air. When two unison tones sound simultaneously the result is louder, but not twice as loud. I would think that it would be the RMS sum of the two separate RMS values of the waves, but does wave phase also come into play? It seems to me that it would, yet that would indicate that two given tones would have a random combined volume, depending on their phase difference.
Here is what I'm trying to do. I have two separate sine waves that are close together. One is at the correct frequency and one needs to be corrected and added to the other. Lets say the correct one is 100 Hz and the other one is 101 Hz. Rather than try to correct (shift frequency) and remix the bad tone, I'd like to determine its volume and increase the correct one by this amount to simulate the equivalent.
So, for example, if the 100-Hz tone is at 70 dB and the 101-Hz tone is at 62 dB, I want the equivalent of what the total volume would be if both tones were at 100 Hz. Then I would amplify the 100-Hz tone to this value and discard the 101-Hz tone in the output.
Incidentally, this is an analog circuit, not DSP. Thanks for any replies.
Don