Well okay, so this isnt really music, but i'm interested in recreating or finding the dolby digital (commonly used in) movies harmonic sweeping noise, i haev a program, goldwave, that lets me insert a function with incremental variables and constant variables, any audiophiles out there that know sound waves adn their functions? just curious 
(Its a good sound to test speakers with imo)
merry christmas!
(Its a good sound to test speakers with imo
)merry christmas!
You need to be able to calculate an amplitude y as a function of the time t in seconds.
Suppost you wanted a sine wave which started at 20Hz and swept upwards by 30Hz per second. You would do something like this:
y = sin( 2*pi*t * (20 + 30*t) )
(pi being 3.14159....)
This will give y's in the range -1 to +1; if this isn't right, and (for instance) the program expects numbers in the -32767 to +32767, you would adjust it to read:
y = 32767 * sin ( 2*pi*t * (20 + 30*t) )
If t isn't in seconds, you will need to adjust it accordingly e.g. if it's in CD samples, replace t with (t/44100) in the above equation.
Hope that gets you started...
Cheers
IH
Suppost you wanted a sine wave which started at 20Hz and swept upwards by 30Hz per second. You would do something like this:
y = sin( 2*pi*t * (20 + 30*t) )
(pi being 3.14159....)
This will give y's in the range -1 to +1; if this isn't right, and (for instance) the program expects numbers in the -32767 to +32767, you would adjust it to read:
y = 32767 * sin ( 2*pi*t * (20 + 30*t) )
If t isn't in seconds, you will need to adjust it accordingly e.g. if it's in CD samples, replace t with (t/44100) in the above equation.
Hope that gets you started...
Cheers
IH
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