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Spectrogram Help

Printed From: Aurora
Category: Aurora Sequencer Software
Forum Name: Aurora 1.0
Forum Discription: This is the place to discuss (and report bugs) the 1.0 version of Aurora
URL: http://www.aurorashow.com/forum/forum_posts.asp?TID=958
Printed Date: 24 Jun 2025 at 3:14pm
Software Version: Web Wiz Forums 9.06 - http://www.webwizforums.com


Topic: Spectrogram Help
Posted By: rcrick
Subject: Spectrogram Help
Date Posted: 11 Dec 2009 at 8:38pm
I am having difficulty using the Spectrogram. I can use any help and advice on the use of this function. I there anything I can read or watch to better understand the use of this.



Replies:
Posted By: LightsOnLogan
Date Posted: 14 Dec 2009 at 7:52am

One of these days I'm going to bring a truckload of audio gear to an event (a mini or PLUS) and do a whole hour presentation on this view alone and have it taped.  One of these days...

In the meantime, 25% just "get it" the first time they see it, 50% can learn it, and 25% can't ever see it and prefer the old view.
 
Here's what you are seeing:
 
Horizontal (X axis):
Time
 
Vertical (Y axis):
Frequency/Pitch/Note. 
Bass notes are at the bottom; midrange in the middle; treble notes are at the top.
 
Color (Z axis):
Energy/Amplitude/Volume
From quiet to loud: blue, cyan, green, yellow, orange, red
The amount of volume at a given pitch is represented by these colors.
 
To get used to usinge this view if it didn't just come to you, I recommend loading in a few practice songs before using it for real.  Here are some recommendations:
 
TSO Wizards:
Love it or hate it, this song is a good introduction to reading the spectrogram.  First look at the note rises in the piano sections (din, dink, dink, dink, dink)... it is easy to see where they begin (attack), sustain, and decay.  Practice in various parts of the song for a bit, then look for the bass guitar in the loud parts.  It is seen as alternating large red bars at the bottom of the spectrogram... easy to pick up a beat off of.  Last, find the chimes in the bridge... those are a real pain without the spectrogram, but you should find them easy after finding the first two.
 
TSO Faith Noel:
This is an example of a song which has a LOT of dynamic compression applied.  Just make a comparison between the amplitude and spectrogram views (A key then S for spectrogram; A key then A for amplitude).  See what you can and can't see in each.
 
Any song with vocals:
Now that you are used to looking at instruments, vocals should seem "different" to you.  See if you can recognize them.
 
Any song from the 50s/60s:
This good for viewing a different decade's recording style.  The instruments "stand out" differently in the "mix".  It is also fun to try to spot imperfections in a recording... musicians coming in later than others, etc. that are typically edited out in the studio in modern recordings.  If working with Elvis, it is easy to find his vocal modulations.  Finding out that he purposely dropped entire syllables out of words that your brain substitutes when listening can make sequencing a pain though.
 
By now you've noticed that there usually isn't just one note, but a stack of lines.  The bottom line in the stack is the "fundamental"... the note you'd play on the piano.  The stack above are the "harmonics".  Different instruments have different harmonics; the same is true for voices.  This is what makes a piano sound different than a trumpet, and my singing voice different than yours (well... maybe... I don't know if you stay on key).
 
Some things, like a snare hit, will have such a sharp attack and quick decay that you can almost make out a vertical line instead of horizontal for them.
 
Beat detection:
This isn't to be relied on as a crutch; it is only as a tool to help with what you are seeing.  Aurora digests all of the information seen in the spectrogram and makes "beat recommendations" at the very top of the spectrogram (the white blocks).  This is where Aurora thinks a beat might be.  It's never as good as human judgement, but it can be helpful at times.


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