Terminology for mastering Audacity

Under construction!

Most of the following terminology is used directly in Audacity. Visit the following link which includes an awesome interactive demonstration of most of the terms we will be discussing: https://pudding.cool/2018/02/waveforms/ ^[1]

1. Sound

Sound is a type of energy made by vibrations. When an object vibrates, it causes movement in surrounding air molecules. These molecules bump into the molecules close to them, causing them to vibrate as well. This makes them bump into more nearby air molecules. This “chain reaction” movement, called sound waves, keeps going until the molecules run out of energy. As a result, there is a series of molecular collisions as the sound wave passes through the air, but the air molecules themselves don’t travel with the wave. As each molecule is disturbed, it oscillates (moves away from a resting point but then returns to it). ^[2]

2. Waveform

A waveform is just a schematic that helps us understand sound waves. They measure an air molecule’s displacement over time. We can adjust the amplitude of a waveform to make it louder or quieter, and we can adjust the frequency of a waveform to make the pitch higher or lower.

The waveform in Audacity is the blue jagged line in the track.

3. Frequency

The number of vibrations per second is referred to as an object’s frequency, measured in Hertz (Hz).

Frequency is a measure of how many times the waveform repeats in a given amount of time. ^[2]

4. Pitch

Frequency is similar to pitch. The faster a wave repeats itself, the higher the pitch of the note. This why if you simply speed a track up you will raise the pitch as well.

5. Amplitude

Measures how much a molecule is displaced from its resting position. It measures the amount of energy being carried. In simple terms, it is represented by the height of the wave.

Intensity is measured in decibels and is perceived as sound volume. Thus, the volume is proportional to the amplitude of the sound wave.

6. dB

A Decibel (“dB”) is a unit used to measure the intensity of a sound by comparing it with a given level on a logarithmic scale.

A whisper is about 30 dB, normal conversation is about 60 dB, and a motorcycle engine running is about 95 dB. Noise above 70 dB over a prolonged period may start to damage your hearing. ^[3]

7. Channel

A channel is a representation of sound coming from or going to a single point. A single microphone can produce one channel of audio, and a single speaker can accept one channel of audio, for example. A digital audio file can contain multiple channels of data.

In Audacity, the sound clip in the track appears as a waveform: the jagged blue lines.

8. Track

When you import a sound file into Audacity you will end up with a single sound clip on a single track.

9. Mono/Stereo

Mono (monophonic) sound is single-channel audio where all the instruments are mixed into one signal, intended to be heard as if emanating from one position. Stereo (stereophonic) sound is achieved by using two audio channels feeding 2 separate speakers.

10. DC offset

DC offset is a mean amplitude displacement from zero. In Audacity it can be seen as an offset of the recorded waveform away from the centre zero point. DC offset is a potential source of clicks, distortion, and loss of audio volume.

11. Gain

Gain is the amount of audio signal increased by an amplifier, and it’s expressed in decibels (dBs). It is the ratio between the input volume and the output volume, and unlike volume, it adjusts the tone of the sound before it gets processed.

12. Clipping

Clipping is a form of waveform distortion that occurs when an amplifier is overdriven and attempts to deliver an output voltage or current beyond its maximum capability. Driving an amplifier into clipping may cause it to output power in excess of its power rating. ^[4]

In Audacity, clipping occurs when the Recording Level meter shows the sound volume in the red all the way up to 0dB. There should be no red lines on your audio track. 

13. Normalize

Normalize is a peak normalization effect that applies gain or reduction to the selected audio so the level of the peak is changed to the desired level. You set the desired level of the peak (in dBFS) before applying the effect.

Use the Normalize effect to:

• set the peak amplitude of a single track (or selection)
• make multiple tracks (or a selection within multiple tracks) have the same peak amplitude
• equalize the balance of left and right channels of stereo tracks.
• remove any DC offset from the tracks. ^[5]

14. Equalisation

“Graphic EQ is a graphic equalizer. Equalisation is a way of manipulating sounds by frequency. It allows you to increase the volume of some frequencies and reduce others. This is a more advanced form of the EQ and Tone controls on many audio systems.” ^[6]

15. Distortion

“The original signal of audio is measured in a waveform. Distortion is a reference to significant alterations of this waveform, whether intentional or unintentional. Technically, any effects that change the audio signal (such as compression or EQ filters) qualify as distortion.” ^[7]

16. Compression

“A process that tends to even out the overall volume level by increasing the level of softer passages and decreasing the level of louder passages.” [8]

17. Reverb

When you record a sound and play it back, it will often sound quite flat and dull. This is because the microphone has probably not recorded the echoes that occur naturally when sounds are reflected off nearby objects and surfaces. To make the sound more natural, you can add reverb (short for reverberation).

Watch this excellent video for an in-depth description.

References:

1. Puddingviz (no date) Let’s Learn About Waveforms, The Pudding. Available at: https://pudding.cool/2018/02/waveforms/ (Accessed: 12 February 2024).
2. Sound (2022) Science World. Available at: https://www.scienceworld.ca/resource/sound/. (Accessed: 19 February 2024).
3. What Noises Cause Hearing Loss? (2022) Centers for Disease Control and Prevention. Centers for Disease Control and Prevention. Available at: https://www.cdc.gov/nceh/hearing_loss/what_noises_cause_hearing_loss.html#:~:text=Sound%20is%20measured%20in%20decibels,start%20to%20damage%20your%20hearing. (Accessed: 19 February 2024).
4. Clipping (audio) (2024) Wikipedia. Wikimedia Foundation. Available at: https://en.wikipedia.org/wiki/Clipping_(audio) (Accessed: 19 February 2/024).
5. Normalize (no date) Normalize – Audacity Manual. Available at: https://manual.audacityteam.org/man/normalize.html (Accessed: 19 February 2024).
6. Graphic EQ (no date) Graphic EQ – Audacity Manual. Available at: https://manual.audacityteam.org/man/graphic_eq.html (Accessed: 19 February 2024).
7. What Is Distortion in Music and How To Use It When Mixing (no date) Soundtrap. Available at: https://www.soundtrap.com/content/blog/what-is-distortion-in-music (Accessed: 19 February 2024).
8. Glossary (no date) Glossary – Audacity Manual. Available at: https://manual.audacityteam.org/man/glossary.html#compression (Accessed: 19 February 2024).
9. Visualising sound (no date) YouTube. YouTube. Available at: https://www.youtube.com/playlist?list=PLK-TnnP2eDKjB4UsMHYJNWl3FaH1PT24p (Accessed: 19 February 2024).