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Audio Spectrum with ultrasound frequency range

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Shimpei Ishiyama
Audio Spectrum with ultrasound frequency range
on Aug 13, 2015 at 11:11:10 am

Hello, I am new for After Effects and CreativeCow.

I want to create a spectrogram using Audio Spectrum effect, referencing this tutorial.
http://cgi.tutsplus.com/tutorials/the-best-sound-youll-ever-see--ae-3167

The beautiful spectrum window in Adobe Audition is ideal. My audio file (.wav) contains ultrasound up to 100 kHz recorded with a special microphone and high sampling rate (250 kHz).


Frequency range I would like to show is between 20 and 100 kHz. However the Audio Spectrum effect has the maximal End Frequency of 22050 Hz, so it does not cover ultrasound range.

Does anybody know how to make a spectrogram of ultrasound?
Alternatively, is it possible to export the spectrum video from Adobe Audition?

Thank you so much.

Shimpei


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Kalle Kannisto
Re: Audio Spectrum with ultrasound frequency range
on Aug 13, 2015 at 4:20:47 pm

Possible idea: Slow your audio down (reinterpreting it, not resampling) so that it falls within the Audio Spectrum range?


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Blaise Douros
Re: Audio Spectrum with ultrasound frequency range
on Aug 13, 2015 at 4:41:16 pm

Actually, resampling is exactly what Shimpei needs to do. Slowdown algorithms are designed to keep the pitch consistent.

Shimpei, if you don't already have it, download the free Audacity program. It has the ability to resample your audio to a lower sample rate, which has the effect of slowing down and pitch-shifting the audio to an audible range. If the audio was recorded at a sample rate of 192kHz, you should resample it to a low enough rate that your 100kHz sounds drop down into the audible frequency range.


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Shimpei Ishiyama
Re: Audio Spectrum with ultrasound frequency range
on Aug 14, 2015 at 8:54:49 am

Preserving the spectrogram look is the most important for my project. I've tried slowing down and pitch shifting using Audacity, Adobe Audition and another software, but unfortunately the spectrum was somewhat distorted.


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Shimpei Ishiyama
Re: Audio Spectrum with ultrasound frequency range
on Aug 14, 2015 at 8:47:18 am

Thank you for the comment. Slowing down is an option, though I want to play the movie at real time in the end.


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Dave LaRonde
Re: Audio Spectrum with ultrasound frequency range
on Aug 13, 2015 at 4:46:44 pm
Last Edited By Dave LaRonde on Aug 13, 2015 at 5:46:26 pm

The look in that tutorial and the look in Adobe Audition are VERY different! One is done in 3D in AE, animating in time with the music. The other is a 2D image of a waveform over time. Replicating each look requires the use of very different techniques.

Before we could offer really useful advice, you would need to describe in greater detail what you want the viewer to see.

If you want the 3D animation, you could use Audition to change the pitch of the audio until it is in the audible range, then use the audio file in AE.

Dave LaRonde
Promotion Producer
KGAN (CBS) & KFXA (Fox) Cedar Rapids, IA


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Shimpei Ishiyama
Re: Audio Spectrum with ultrasound frequency range
on Aug 14, 2015 at 9:11:33 am

Thank you for your comment.

What I need is just to represent the ultrasound spectrogram precisely either in 2D or 3D, and I thought both could be generated by using Audio Spectrum. For example, I could possibly change the color of the spectrum when the audio level exceeds a certain threshold and set the height zero, so that 2D image could be generated.

Is there any other way to generate 2D spectrogram in AE such like in Audition?


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Kalle Kannisto
Re: Audio Spectrum with ultrasound frequency range
on Aug 14, 2015 at 12:51:31 pm

Slowing down would be just to get the ultrasound audio in the right frequency range for Audio Spectrum. You can speed up the resulting animation to play back in real time.

For generating the 2D spectrogram it sounds like you're already thinking of the same method I am, which is to use the audio spectrum and render it through time. I would imagine you can do it either as cumulative render or with a large number of (horizontally thin) layers going from right to left with time offset on each.

Or then you could employ a plug-in, if you have access to them. Particular or Form might be able to render the frequencies as particles that persist through time.


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Shimpei Ishiyama
Re: Audio Spectrum with ultrasound frequency range
on Aug 16, 2015 at 1:26:09 pm

I'm struggling on slowing the audio down without the spectrogram distorted. I guess the built in Audio Spectrum has a max_freq parameter set to 22050 and it'd be so easy if I could change the parameter...

I didn't know the cumulative render. I will check it out.

Thank you so much!


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Kalle Kannisto
Re: Audio Spectrum with ultrasound frequency range
on Aug 16, 2015 at 2:33:06 pm

Cumulative render = CC Time Blend (available up to AE CC2014, removed in CC2015).


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