Audio Editing
This section of the specification covers various processes that are useful to know about when it comes to audio editing in your DAW. These processes include truncating audio clips, removing and explaining clicks and noise, normalising, and inverting waveforms.
Specification 👇
Component 1 Specification
Component 2 Specification
Component 3 Specification
Component 4 Specification
Truncating
One of the simplest audio editing processes is truncating, or shortening an audio file. You may want to shorten an audio clip if the start and/or the end of the file is not needed, or if the recorded audio is bordered by silence (you want to remove silent parts of audio files as they might not actually be ‘silent’ and contain low level hiss, which can make for an unclean mix). Truncating the file may also make the lead-in and lead-out (or start and end) times clearer.
In your DAW, you can truncate a file by using the scissor or split tool. By clicking on the waveform where you want the file to be split or shortened to, you can then easily remove unwanted segments of audio.
Original Audio File
Truncated Audio File
Explaining and Removing Clicks and Noise
Clicks
Clicks can be caused by cutting a waveform somewhere other than a zero-crossing point, creating a discontinuous waveform. This causes a clicking sound because the waveform doesn’t come to the end of its cycle naturally and stops abruptly. A way to avoid this is ensuring that you always cut on a zero-crossing point. For more information on zero-crossing points, go to this page here.
Clicks can also be caused by plosives. A plosive is “a sound which results from letters such as ‘P’, ‘B’ and ‘D’, which when spoken directly into a microphone can result in a low frequency ‘pop’ sound [or click sound] due to the strong air movement on a microphone’s diaphragm.” A way of avoiding plosives can be to use a pop shield or to position the microphone further away from the performers mouth.
Noise: Hiss, Hum and Plosives
Hiss is a broadband noise that spans the entire audible spectrum. It can be caused by your equipment having a high noise floor . Due to hiss spanning the entire audible spectrum, it is impossible to remove it at the mixing stage with EQ because you will lose the sound that you wanted to record as well. Making sure that background noise is kept to a minimum (AC and heaters off, windows closed etc) can help with this problem, as well as trying to maximise signal-to-noise ratio (more info on this here).
Hum is a continuous low frequency sound typically with a frequency of 40-80Hz. Hum can be caused by electrical interferences or ground loops. You don’t need to know about ground loops but eliminating electrical interference can be done by using balanced cables (more on this here).
When it comes to dealing with hiss and hum at the mixing stage, while not a lot can be done to remove it, you can attempt to draw less attention to it. As mentioned above, it’s good practice to remove silent parts from your audio files as, if they’re left in and have hiss and hum problems, they can unnecessarily add to the amount of noise in your mix. However, in removing them, it can make it more obvious when an audio file starts or stops as the amount of noise will suddenly increase or decrease.
An audio editing technique that can be used to manage this problem is using fades and crossfades. Adding a fade-in at the start of an audio file and a fade-out at the end can make the noise level change less noticeable. If you have two audio files in close succession of one another however, it can be beneficial to leave the silent parts of the audio files and crossfade between them. A crossfade “creates a smooth transition between audio files by fading one out whilst the other fades in."
Audio File with Fade Ins and Outs
Audio File with Crossfades
Normalising and Inverting Waveforms
Normalising is “the boosting of audio by the same amount so that the relative volumes remain the same. Commonly used to boost to the peak volume to the maximum level before distortion.” For more info on normalising, visit this page from Higher Hz.
Inverting a waveform means positive values (anything above the zero-crossing line) become negative values, and vice versa. This process normally doesn’t cause any audible change to the sound, but it does change its polarity which, when combined with other waveforms can affect the sound of a mix as it can “counteract the effects of phase cancellation.”
Original Audio File
