synthetic wow

One can generate tones in CE. If these tones were being played back from some mechanical device, such as a tape player or a turntable, there might be wow and/or flutter. Those defects would make the tones vary in frequency, probably at some fairly regular rate, no?

Suppose I want to hear what wow of varying amounts sounds like and how much wow there has to be for me to hear it. Is there a reasonable way to generate tones that have the characteristics of wow from mechanical playback?

I observe that if I generate a tone (e.g. 440 A) with
Modulate By = 10 Hz
Modulation Frequency = 1 or 2 Hz
I seem to get the effect, but I don't understand it. Is the base tone actually varying in frequency in the way that wow effects playback?

Wow is generally expressed in %. I would like to be able to listen to 1%, 3%, whatever number I want, to see what it is like. Is this possible?

Measuring wow and flutter on such machines is normally done using a frequency of about 3.125K. In the measurement device the original tone is removed and the level of the remaining frequencies is measured. I believe that the measurement doesn't usually include any information about the speed or depth of the resulting modulation.

[I believe that the measurement doesn't usually include any information about the speed or depth of the resulting modulation.]

Wow is generally expressed in %. I would like to be able to listen to 1%, 3%, whatever number I want, to see what it is like. Is this possible?

Yes, after a fashion. Just modulate a 3.15kHz tone generated in Audition by whatever frequency you want to hear (try putting the same number in both modulation boxes). This won't give you complex modulation effects, though, which wow and flutter generally contain.

Measuring wow and flutter on such machines is normally done using a frequency of about 3.125K. In the measurement device the original tone is removed and the level of the remaining frequencies is measured. I believe that the measurement doesn't usually include any information about the speed or depth of the resulting modulation.

Actually it does - because if it didn't, it wouldn't be a lot of use. Generally these days a combined figure is used, and the subjective expereience is weighted either side of 4Hz, (IEC 386 flutter weighting) which is supposed to be the frequency at which the annoyance level is greatest. It's expressed as a percentage variation in pitch, and the figure is always the greatest value measured, and the frequency is stated.

I knew Steve would know the answer.

I should also have pointed out that even when the cause of flutter appears to be quite straightforward, an analysis of the signal won't always get you there immediately. A regularly modulated frequency would only represent the rotation of something cyclically off-centre, whereas more common causes of problems of this nature are things like idler wheels with a detent in them, and these throw up a load of extra harmonics when you hit the detented section, because there is a rapid instantaneous rate of change, which promptly stabilises again during the time when the undamaged part is revolving.

What this means is that it's pretty hard to synthesise accurately what real wow and flutter sounds like.

For fun with wow and simulated analogue replay anomalies you could download Izotope's free Vinyl plug-in:

http://www.izotope.com/products/audio/vinyl/

I want to listen to differences and know what they are. I strongly prefer flutter not be a part of it, if possible. I want to be able to produce a signal that has 0.5% wow, 1.0% wow, 0.25% wow, etc. I still can not figure out how to accomplish that.