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sound spectrogram programsRecently, I was working on a story involving a person that made a phone call, which was recorded. That person later refused to admit that they’d ever made the call at all.

With the recorded voice from the phone call and a clip of the person denying the accusation, I set to work trying to find a way to prove that the voices were one and the same.


I admit that I’m a bit obsessed with voice technologies. This is why I’ve been waiting for Google Voice How To Use Google Voice To Blog Over The Phone How To Use Google Voice To Blog Over The Phone Read More to become more advanced with its voice recognition technology, and it’s why I love PC voice control apps like Tazti Tazti - Search Web, Play Music & Control Programs using Voice Tazti - Search Web, Play Music & Control Programs using Voice Read More . However, when it comes to digitally comparing voices, I was at a loss. You’ve probably seen those spy movies where the computer can automatically identify the voice of a known criminal with the voice print alone.

To be honest, once I discovered Sonogram Visible Speech, I realized that spectrogram voice technology actually is currently a viable way to solidly identify a person by their voice alone.

Understanding Spectrogram

If you know about chemical isotopes, then you know that with isotopes, chemists can identify the chemical makeup of compounds by isolating the basic elements and using the breakdown to identify the individual components of any mixture. In much the same way, an audio spectrogram breaks down audio sound into basic frequencies. The interesting thing about the human voice is that no one speaks in one frequency. Your mouth, nasal passages and the structure of your voice box determines the mixture of frequencies that make up your somewhat unique voice.

Sonogram Visible Speech is a free spectrogram software application that will take video or audio files and break down the audio track into the entire spectrum – all of its frequencies throughout the entire time frame of the track. A completed spectrogram looks like the image below.

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sound spectrogram programs

As you can see, the bottom track looks like the basic sound wave that you’d see in a program like Audacity 3 Audacity Tips To Enhance Your Recorded Interviews 3 Audacity Tips To Enhance Your Recorded Interviews Read More , however the center pane displays each segment of the sound file in its entire frequency layout. The amazing thing about this software is that there are many other waveforms you can use to examine your sound file. These are especially for advanced users.

sound spectrogram programs

You can configure how each of those wave forms displays by going into the the “Options” menu, and selecting “General Adjustment.” Here you can define how the logarithmic graphs calculate output and the general display setup of all available charts.

digital sound spectrogram

If the sound is fairly quiet, or the voice you’re analyzing is a whisper, you may want to consider using the logarithmic frequency display. You enable it from the “Options” menu and select “Logarithmic Frequency.” This will somewhat “magnify” the significant areas of frequency in the spectrogram.

digital sound spectrogram

This can really help to identify clear frequency patterns that identify someone from the sound of their voice. If you’re completely lost, and you don’t know where to start, clicking on “Help” and going to “Online Help” will open up the very well written Sonogram Online Help manual. This is a great place to start if you’re new to spectrogram audio analysis.

digital sound spectrogram

An Experiment With Spectrograms Using Ghost Hunting

The beauty of this software is that it is good for many different uses. One of the artifacts that comes up often in ghost hunting, a personal interest of mine, is “electronic voice phenomenon” – where the voice of an apparition or ghost allegedly shows up on audio recordings. These recordings are scattered throughout the web, so I decided to pull a few off of the ghost hunter websites and do a spectrogram analysis.

The spectrogram shows that the frequencies of the voice are generally low, but to get a better picture of the voices in the recording, you need to open up the additional waveforms. The Autocorrelation View calculates “pitch” in the time frame where you hover the mouse.

The “ghost” has an average pitch frequency of about 129.0 hz. Scrolling to the end of the recording where you hear the investigator’s voice, the calculated pitch frequency is about 208.0 hz (which makes sense because it’s a female voice and the ghost recording sounds male.)

Opening up the Fast Fourier display reveals even more detail about the voices. This chart quickly breaks down the primary frequencies and displays them in a color code.

In this case, the breakdown of frequencies is spread apart, with some high, but a good number of low frequencies in the mix as well. However, the investigator in the room is clearly speaking in a voice that is clustered in frequency more toward the high end of the range, as shown here.

This quick analysis proved that the two voices are quite different, but this is only a basic example of the capabilities of this powerful software. Basically, any situation where a breakdown of frequencies of a sound wave can help – this is the software for you. It’s easy to learn, quick to set up and configure, and it performs as well or better than any paid spectrogram software on the market.

Do you have any projects that could use a spectrogram? Have you ever tried Sonogram Visible Speech? Share your insight in the comments section below.

  1. Ryan Dube
    August 28, 2010 at 4:15 pm

    Karl - not sure what browser or OS you're using. But when I click on the link for the Windows installer file, it takes me to the SourceForge page and downloads the app just fine.

  2. Karl K
    August 28, 2010 at 3:32 pm

    This would be a MARVELOUS adjunct to anyone working with audio in the "nitty-gritty" region (as I do), ham radio operators and so on. However, when you go to the home page of Spectrogram and try to download the program from ANY of the links, they don't work! That is, you'll get a blank page in your browser, but no activity from the their file server.

  3. Ryan Dube
    August 28, 2010 at 12:57 am

    Thanks! No, as far as I know this software only breaks down audio into the full spectrum of frequencies. One neat software app that I wrote about previously that does convert text to voice is the Text to Voice Firefox extension.

    http://www.makeuseof.com/dir/t...

  4. Ryan Dube
    August 27, 2010 at 10:57 pm

    Thanks! No, as far as I know this software only breaks down audio into the full spectrum of frequencies. One neat software app that I wrote about previously that does convert text to voice is the Text to Voice Firefox extension.

    http://www.makeuseof.com/dir/text-voice-firefox-extension-vocalizes-highlighted-words/

  5. Loen210
    August 27, 2010 at 8:44 pm

    Thanks for posting this Ryan,

    Question: Since I am new to this (can't find simple explanation)...

    But does this record words into text? Wondering for usage of those paralyzed or handicapped, if they can use this to wriet notes/emails?

    Thanks!

  6. Loen210
    August 27, 2010 at 6:44 pm

    Thanks for posting this Ryan,

    Question: Since I am new to this (can't find simple explanation)...

    But does this record words into text? Wondering for usage of those paralyzed or handicapped, if they can use this to wriet notes/emails?

    Thanks!

    • Karl K
      August 28, 2010 at 3:30 pm

      No, it doesn't record words to text! It only displays the frequency and spectral contents of a voice (or other sound, such as music).

  7. Ryan Dube
    August 27, 2010 at 1:07 pm

    Hi Irha,

    Thanks for the great feedback. The software would be considered advanced audio analysis, so part of the problem may be that if you don't know too much about audio, than many of the pictures won't make sense. With that said, your point about requirement more words and fewer snapshots is very well received! Thank you!

  8. Ryan Dube
    August 27, 2010 at 11:07 am

    Hi Irha,

    Thanks for the great feedback. The software would be considered advanced audio analysis, so part of the problem may be that if you don't know too much about audio, than many of the pictures won't make sense. With that said, your point about requirement more words and fewer snapshots is very well received! Thank you!

  9. Anonymous
    August 27, 2010 at 5:39 am

    Thanks for introducing what seems like a very powerful software. I don't know too much about audio, but I read the entire article and I couldn't really make out what is going on. The matter and pictures seem incoherent, as in most cases, I can't tell how the picture is adding value. There is only a few places I could figure out why there is a picture (e.g., when you refer to the calculated pitch frequency is about 208.0, I can see that the picture shows the same). I think you should reduce the number of snapshots and try to explain some of the concepts a little more. In fact, it would even help if you explains a little more about the "ghost" concept.

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