Audio Recording

The default waveform settings in Audacity in Ubuntu is a scale from -1.0 to +1.0; the waveform varies alternately with +1.0 as the loudest (this can also be applied in Windows operating system if the default scale is the same). See example below:

You noticed that when there is no volume , it will all be a straight line and the amplitude is 0. Subjective, you can say that the audio waveform depicted on the screenshot sounds so weak and needs to be amplified/compressed to make it loud.

This is where the default waveform dB chart settings in Audacity needs to be changed. When you are doing compression, you need to look at the very important components of your waveform objectively in order to make sound decisions, these are the things to look at:

a.) Maximum Peak Signal in dB.
b.) Average signal in dB.
c.) Noise level

As you can see, since the default waveform settings is in a scale of -1.0 to +1.0, you cannot determine the maximum peak signal in dB units. So lets change the audio waveform so that the vertical axis will be using decibel units.

These are the steps:

Step1: Launch Audacity.
Step2: Go to Edit – Preferences.
Step3: And click “Tracks”.
Step4: Change the “Default View Mode” from “Waveform” (this is the default) to “Waveform (dB)”.
Step5: Click OK.
Step6: Go to File – Exit.
Step7. Launch Audacity again.
Step8. Open any audacity project (those with .aup extension) by going to File – Open. If you do not have a .aup project yet, you can open any wav file.
Step9. When the project has been open, you will see that it is now using a decibel y-axis of the audio waveform.

It should look like this:

You will notice that the scale of -1.0 to +1.0 in the y-axis has been replaced with decibel values.

Basic audio waveform interpretation:

1.) You will notice that on the above screenshot, the audio waveform peaks at around -24dB which is of course, way to far from the maximum possible amplitude which is 0dB.

2.) It also shown that the weakest amplitude of the waveform (can be considered as the noise level) started at around -60dB and below.

3.) So we can say that the waveform peak volume is roughly around -30dB to -48dB (between the maximum and minimum audio waveform peaks.)

Now you have analyzed the waveform, you can now start using these data when doing audio wave compression in an attempt to make the waveform as loud as possible without getting distortion.