Sound Related Equations
For the sake of sanity, the use of calculus is kept to a strict minimum.
 

Sound Intensity Based on Distance from Source

 D=10*LOG((P/4pR2)/10-12)







    This equation takes the power of a sound and and gives you the decibel rating.  D is the decibal rating of a sound.  P is the power of the source in watts.  R is the radius in meters.
 
 




Perceived Frequency of Sound When You Move
Toward or Away from a Sound Source

FHeard=FActual*(1+(VYou/VSound))








    Here is a neat equation for getting the percieved frequency of a sound source that you are approaching or leaving.  FHeard is the frequency that you hear. FActual is the actual frequency of the source. VYou is the your velocity in M/s. VSound is the sound's velocity in M/s (usually around 344 M/s).  If you are leaving the sound source, then VYou would have a negative value.
 
 




Perceived Frequency of Sound When a Sound
Source Moves Toward or Away from You

FHeard=FActual*(1/(1-(VSource/VSound)))








    Here is a neat equation forgetting the percieved frequency of a sound source that approaches or leaves you.  FHeard is the frequency that you hear. FActual is the actual frequency of the source. VSource is the source's velocity in M/s.  VSound is the sound's velocity in M/s (usually around 344 M/s).  If you are moving toward the sound source, then VSource would have a negative value.
 
 







Perceived Frequency of Sound When a Sound
Source and You Are Both Moving

FHeard=FActual*((VSound+VYou)/(VSound-VSource))








    Here is a neat equation forgetting the percieved frequency of a sound source that approaches or leaves you or you approaching or leaving it.  FHeard is the frequency that you hear.  FActual is the actual frequency of the source.  VSource is the source's velocity in M/s.  VSound is the sound's velocity in M/s (usually around 344 M/s).  VYou is your velocity in M/s.  If you and the sound source are leaving each other, then VYou and VSource would have negative values.
 
 





Get Frequency of N 1/2 Steps Above Given Frequency

Fnew = Fold * 1.059463095 N







Plug the frequency in which you want a highstep higher than into Fold and the number of halfsteps that you want to go up into N.  Please note that it is fine to use sample rates in place of actual frequencies.
 
 



Get Frequency of N 1/2 Steps Above Given Frequency

Fnew = Fold / 1.059463095 N







Plug the frequency in which you want a highstep higher than into Fold and the number of halfsteps that you want to go up into N.  Please note that it is fine to use sample rates in place of actual frequencies.
 
 


Get Frequency of N Octaves Away From a Given Frequency

Fnew = Fold * 2N







Plug the frequency in which you want N octaves higher or lower than into Fold and the number of halfsteps that you want to go up or down  into N.  To go down, use a negative value for N.  Please note that it is fine to use sample rates in place of actual frequencies.
 
 

Return to Physics Menu