Best free VST plugins for analyzing audio

If you use Wavosaur for mastering / premastering, or signal analysis in a more general way, you need tools for audio analysis : spectrum analyzers, phase analyzers, sonogram.
Wavosaur comes with analyzers, you’ll find them in the ‘tools’ menu, along with oscilloscopes & statistics about the sound file (maximum sample peak, RMS power, average value..).

But you can also use VST plugins (for some people it can be more convenient).
We have searched deep deep inside deep deep down inside into the web, to find the best free VST plugins for audio analysis, here’s the selection:


1) Spectrum Analysis

1.1) Voxengo SPAN


This spectrum analyzer uses FFT to display the signal frequency in real time.
You can freeze the display, and use the mouse to shows dB values / Frequency value
Frequency is displayed in Hz and in musical note.
The Voxengo SPAN analyzer also displays statistics : RMS power, and it features a clipping detection.

More info and download @
It is worth mentioning these plugins too, freeware!

1.2) Mdsp SmartElectronix Fre(a)koscope


Very nice, with interesting options for the spectrum display : linear/logarithmic/semitones ..
Adjustable size for the FFT buffer. Had sometimes display problem with Wavosaur.
More info and download @



1.3) BlueCat FreqAnalyst


Like the previous VST effect, this one can show spectrum of left / right channel or both, has a “hold peak” feature that is interesting, when dealing with EQ level in your mix.
More info & download @



1.4) Seven phase Spectrum Analyzer

Spectrum Analyzer seven phase

This one is freely resizable inside the host application (works in Wavosaur)
More info and download @



1.5) MultiInspector free


Download @



2) Sonogram

2.1) ag-works sonogram sg-1


This free plugin displays a scrolling sonogram for frequency analysis.
You have the choice for the sonogram colors, and many options to tweak the sonogram displays
This is the only sonogram VST we have found for free ! Fortunaly it’s very good.
More info & download @



3) Goniometer

3.1) Flux Stereo Tool


When you need to visualize your stereo position, and the repartition in the field, this plugin is very useful. You can check for phase errors in your mixes.
download @



3.2) Gonio3


download @



3.3) HOFA 4U Goniometer & Korrelator


download @


If you think that we have forget some free VST analyzer plugin in this list, do not hesitate to comment !


We just have found this pretty nice analyzer somewhere on our harddisk :

Dust Analyzer:

It provides three modes : spectrum / scope / phase , with “hold peak” option,  freeze option, dB/Freq display with mouse, linear / logarithmic scale



more info & download @ KvR audio forum  &

14 thoughts on “Best free VST plugins for analyzing audio

  1. Pingback: Hearing Test , what’s your hearing range | Blogosaur

  2. Mark L

    I’m looking for a plugin to analyze speech patterns. So I have a podcast, and I get a different file for each speaker. I’d like to be able to easily analyze, for a given speaker: what % of the time was the person talking (sound vs. silence) and what was the average length of the person’s speeches (and how many speeches there are). Ideally for both of these, I’d like to be able to set a parameter for what gets counted in the measurement: so for length of speeches, if a speech is less than 14 sec (or whatever value), then it doesn’t get counted as a speech at all. Also, what gets counted as a speech? Well, as with a noise gate, you should be able to say how long a pause is between sounds counts as a break in a speech and starting a new one.

    Has anything like this ever been made, or are there clever ways to use existing plugins that I’m not figuring out to do something like what I’m talking about? Sound Forge has a built in “statistics” plugin that does not seem to do the job.

    1. Wavosaur Post author


      i don’t know any plugin able to do speech pattern analysis.
      that’s an interesting feature, but i think this deserves a specialized application.

    2. Andre Onate

      This is a free visualizer also. I found this as I was searching for these type of programs, and have been using it for a few years now. Pretty awesome imo. Many options, many. You can tweek the colors also to you own liking as well as adjust the log/linear view for the spectrum. I’m posting a pic of what I consider an optimum view. This sound is simply a type ring modulated sine wav pitching down and filtered out. The best free visualizer I have encountered.

  3. Renato

    Voxengo SPAN is not freeware, it mutes the audio periodically. I’ve deleted all Voxengo products from my PC, as I was searching for FREE vsts.


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