visualizing sound with reaper

7/25/2019 Visualizing Sound With Reaper

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Hello, I’m Michael Aeschbach fr om Zurich, Switzerland. This lesson is for week 1 of Introduction

To Music Production at Coursera.org. I will be teaching visualizing sound (with Reaper).

The audio we will be looking at consists of a single note (F4) played with an Oboe. It is taken

from the first track of the CD that comes with the Book Peter Veale, Claus-Steffen Mahnkopf,

The Techniques of Oboe Playing, Bärenreiter Verlag, 1998.

To look at the audio, on a new project (File > New project ), we must first create a new track and

import it (Insert > Media file…).

In the main view of the DAW, you see the waveform display of the audio file.

This view is similar to an oscilloscope. Unfortunately, Reaper doesn’t come with its own

oscilloscope but you could download Skope, an oscilloscope plugin for Reaper from

http://jsplugins.supermaailma.net/jsplugins.php .

For this lesson, we’ll simply use Reaper’s waveform display.

http://jsplugins.supermaailma.net/jsplugins.php

http://jsplugins.supermaailma.net/jsplugins.php



To better view the waveform of our audio file, we normalize the inserted item (Item > Item

processing > Normalize items).

In the main view’s waveform display, the Y-axis represents the amplitude of the sound and the

X-axis represents time. You see a representation of the compression and rarefaction of sound in

the air over time.

In the upper part of above image, you can see time units (below the bar: 0:02.542, 0:02.546,

0:02.550, etc.). At marker 0:02.546 , you see the attack of the note and the increase in amplitude

of the sound.

The visualization of sound in the waveform display comes with limitations. For example: it would

be too difficult to see the timbre of the played note, hidden in the waveform.

To see the frequencies of the sound at a given time, we use a spectrum analyzer and if we want

to see how the frequencies change over time, to have a full picture of the sound, we use a

spectrogram analysis. Fortunately, Reaper comes with plugins for both, for a spectrum analysis

as well as for a sonogram.

To use these plugins, we add them to the track as FX by pressing the FX button ( Show Track

FX Window ) and then searching under the section JS for the Frequency Spectrum AnalyzerMeter and for the Frequency Spectrograph Meter .



The Frequency Spectrum Analyzer Meter or spectrum analyser shows us the energy at different

frequencies at a given moment. The X-axis represents the frequency in Hertz and the Y-axis the

amplitude in dBFS.

The fundamental frequency of the note F4 is fixed at 349.23Hz (Frequencies of Musical Notes

http://www.phy.mtu.edu/~suits/notefreqs.html ).

In the spectrum analyser, we see the first spike, the fundamental, at this frequency.

Furthermore, we can see the oboe’s richness in overtones and the interesting fact, that the

amplitude at two of the harmonic series’ partials is higher than the amplitude at the fundamental

frequency.

To see how the frequencies change over time, we have to look at the Frequency Spectrograph

Meter or sonogram.

http://www.phy.mtu.edu/~suits/notefreqs.html



What we see in the above image is a loop over the played note. The X-axis represents time, the

Y-Axis the frequency (lower frequencies at the bottom) and the Z-axis (color) the amplitude or

energy at a given time/frequency.

A combination of these three sound visualizers gives us a good visual representation of sound.

visualizing sound with reaper

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