Hello Jocelyn,

Nice to talk to you in email. Please say hello to Mary for me~
Regarding your question about creating a signal-noise pair of S/N=5dB, I would create a white noise in Praat,

   New ==> Sound ==> Create Sound...
   Formula: delete the 1/2*sin(2*pi*377*x) part
   adjust other parameters (e.g. same length as the signal)

and get the intensity of the noise in dB.

   Query ==> Get intensity (dB)

You can get the intensity of the signal in dB in the same manner.

Since S/N ratio is 5, the intensity(of signal) - intensity(of noise) = 5 (Not sure about this. You'd better double-check on this). You can adjust the intensity of the two files independently;

   Modify ==> Scale intensity...

When you're done with the intensity, say 70dB for the signal and 65dB for the noise, combine the two sounds by following this scriptlet;
   (Assuming that you've got two sound objects "signal" and "noise")

   select Sound signal
   Copy... combined
   Formula... self[col] + Sound_noise[col]

If I remember correctly, I think I was able to combine sound objects by using some command under "Combine sounds..." button, but obviously I was wrong. I asked for help from the Praat-Users group and I got the scriptlet from two guys. As you can see, it's just a formula for adding the y-coordinate of the two sound objects. Hope this was what you and Mary was looking for.

Regarding the E-prime, I can't help you there. You'd better ask Soyoung for help, who is an expert with E-prime.

Cheers,

Kyuchul Yoon


> I think I used to be able to do this, but obviously I forgot how to do
> it. I'd like to "combine" two sine waves of different amplitudes and
> frequency into a single complex wave. I created two sine waves (1Hz
> and 10 Hz with different amplitude values), selected both, and tried
> various things under "Combine sounds-" button. Nothing produced what I
> want. Is there a way to add the y-coordinate of multiple sine waves to
> produce the complex wave? I'd like to show my students how simple
> waves combine to form a complex wave.


This is possible with the Formula option, see the following script:

frq1 = 100
frq2 = 500
amp1 = 0.3
amp2 = 0.2

Create Sound... sine1 0 1 22050 'amp1' * sin(2*pi*'frq1'*x)
Create Sound... sine2 0 1 22050 'amp2' * sin(2*pi*'frq2'*x)

select Sound sine1
Copy... bothSines
Formula... self[col] + Sound_sine2[col]

- - - - - - - - - - - - - - - - - - - - - - - -
Holger Mitterer, Ph.D.
Max-Planck-Institut f?r Psycholinguistik
Postbus 310
6500 AH Nijmegen
The Netherlands
Phone: (+31) (0)24 - 3521372
Fax: (+31) (0)24 - 3521213

=======================
Dear Kyuchul,

Select two Sound objects and run this script.
Two sound objects must have the same sampling frequency and length, and they
must have different names.

-----
sound1$ = selected$ ("Sound", 1)
sound2$ = selected$ ("Sound", 2)

select Sound 'sound1$'
Copy... added

Formula... self[col] + Sound_'sound2$'[col]
-----

masahiko komatsu