module: twenty_db_rolloff_noise
parameters: double n_off, double f_off
inputs: 
outputs:  double out
static_variables: double noise_var, double e
classes: Filter filt("1","s","Ts",Ts), Rand randg("gauss");
init: 
noise_var = f_off*f_off*pow(10.0,n_off/10.0);
code:
e = sqrt(noise_var/Ts)*randg.inp();
filt.inp(e);
out = filt.out;
