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3999hz Sine at 8khz SR, Generated by Audacity to prove a point.
hornpipe2
post Aug 30 2013, 21:04
Post #1





Group: Members
Posts: 5
Joined: 30-August 13
Member No.: 109888



Here is a 5 second tone produced by:

* Start Audacity
* Set Project Rate to 8000hz
* Generate -> Tone
- 3999hz
- 1.0 peak amplitude
- 5 sec duration
* Export as 16-bit 8khz WAV.

Shannon-Nyquist says: my 8khz wave file should perfectly capture my 3.999khz sine wave, because 3.999khz < (8khz / 2).

Now my question: Why, oh why, does Audacity, foobar2000, WMP et al play this back with beats? There is a .5sec periodic amplitude osc going on.

What setup do I need to hear this played back as a pure 3.999khz tone?
Attached File(s)
Attached File  tone.wav ( 78.17K ) Number of downloads: 90
 
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Posts in this topic
- hornpipe2   3999hz Sine at 8khz SR   Aug 30 2013, 21:04
- - saratoga   QUOTE (hornpipe2 @ Aug 30 2013, 16:04) No...   Aug 30 2013, 21:08
- - hornpipe2   Ok... REALLY not understanding. If the second vid...   Aug 30 2013, 21:53
- - greynol   Why not try a signal at -3dB? Also, I hope you re...   Aug 30 2013, 22:11
- - hornpipe2   saratoga I don't think that's it. Here is...   Aug 30 2013, 22:12
- - Silversight   I don't know about the math here, but I can at...   Aug 30 2013, 22:15
- - hornpipe2   Yes Greynol, re: Audacity lines, I watched this ea...   Aug 30 2013, 22:23
- - saratoga   I doubt that article claims that you can perfectly...   Aug 30 2013, 23:59
- - xnor   I have no idea what you guys are talking about. W...   Aug 31 2013, 01:40
- - hornpipe2   I think this is all making sense to me now. I gen...   Aug 31 2013, 04:33
- - ktf   There's a simpler explanation: Nyquist-Shannon...   Aug 31 2013, 09:01
- - bandpass   QUOTE (hornpipe2 @ Aug 31 2013, 04:33) Is...   Aug 31 2013, 10:05
|- - C.R.Helmrich   QUOTE (xnor @ Aug 31 2013, 02:40) When I ...   Aug 31 2013, 11:01
|- - ktf   QUOTE (C.R.Helmrich @ Aug 31 2013, 12:01)...   Aug 31 2013, 15:54
|- - xnor   QUOTE (C.R.Helmrich @ Aug 31 2013, 12:01)...   Aug 31 2013, 16:27
- - xnor   A very pragmatic explanation: When you sample a s...   Aug 31 2013, 14:24
- - saratoga   Its nonlinear because you put in one tone and got ...   Aug 31 2013, 17:56
- - xnor   Sure but once you have the two tones (which you ge...   Aug 31 2013, 18:38
- - greynol   ...so long as the rest of the process up to the so...   Aug 31 2013, 18:51
|- - xnor   QUOTE (greynol @ Aug 31 2013, 19:51) ...s...   Aug 31 2013, 19:18
|- - saratoga   QUOTE (greynol @ Aug 31 2013, 13:51) What...   Aug 31 2013, 19:33
|- - C.R.Helmrich   Thanks, ktf and xnor, now I get it. I was thinking...   Aug 31 2013, 21:32
|- - greynol   QUOTE (C.R.Helmrich @ Aug 31 2013, 13:32)...   Sep 1 2013, 03:00
||- - xnor   QUOTE (greynol @ Sep 1 2013, 04:00) I thi...   Sep 1 2013, 03:38
|- - stv014   QUOTE (C.R.Helmrich @ Aug 31 2013, 22:32)...   Sep 1 2013, 09:14
- - bandpass   Here are some pics which may help. Generate a ton...   Aug 31 2013, 19:21
- - saratoga   Aliasing is nonlinear distortion so I don't se...   Aug 31 2013, 19:37
|- - xnor   QUOTE (saratoga @ Aug 31 2013, 20:37) Ali...   Aug 31 2013, 20:15
|- - Banned   QUOTE (saratoga @ Aug 31 2013, 20:37) Ali...   Aug 31 2013, 22:15
|- - xnor   QUOTE (Banned @ Aug 31 2013, 23:15) Alias...   Aug 31 2013, 22:20
- - saratoga   What is the fft of Sox's output? I suspect tha...   Aug 31 2013, 20:20
- - xnor   Well, yeah if you already know the answer you...   Aug 31 2013, 20:36
|- - bandpass   QUOTE (xnor @ Aug 31 2013, 20:36) Regardi...   Aug 31 2013, 21:24
- - phofman   The spectrograms generated by sox look and sound s...   Aug 31 2013, 20:41
- - Alexey Lukin   Audition's interpolation depends on your zoom ...   Sep 1 2013, 03:53
- - greynol   Thanks everyone. Sorry for not getting it the fir...   Sep 1 2013, 06:33
- - stv014   Using the resampler from here with the "-r 44...   Sep 1 2013, 09:34


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