I would like to create a sound with three sine waves. The first sine wave is the fundamental frequency (f0), the second wave is a harmonic (f2), the third is also a harmonic (f4) of the base frequency. The harmonics should have a sound pressure level ratio (between the sound pressure level of the fundamental and the sound pressure level of the harmonics) to the base freqency of +/- 15dB.
What factor do I need to multiply the amplitude of the sine waves with, to achieve the +/- 15dB sound pressure level ratio?
I generate the sound inside a program and I can control the amplitude of the sine waves.
I have tried
- this table that led me to the conclusion: a2 = a0 / 10 / 3.162 (which resembles
-15dB = 10 * log(a0/a2)
- this formula:
-15dB = 20 * log(a0/a2)that led me to the conclusion a2 = a0 * 0.1778
Those two give significantly different results. Which one should I use to calculate the amplitude to achieve the sound pressure level ratio?
f0 = f2 / 2 = f4 / 4 a2 = ? * a0 a4 = ? * a0