How an Audio Engineer Sees Your Sound
An overview of the visual tools used by audio engineers today.
How does an audio engineer see sound? That's probably not a question that comes to mind very often, if ever. But it's a fascinating question nonetheless. Audio professionals rely heavily on their well-trained ears, of course, but we also have some incredible visual tools at our disposal that are truly captivating. The world of audio engineering that I surround myself in is a mystery to most, which is why I'm excited to showcase some of the ways in which we see sound.
This article will contain a basic overview of the visual tools I use while working on audio projects in an order which they typically appear. If you wish to learn more about a specific visual tool see Resources and Additional Learning Materials at the end of this article or reach out to me directly via the comment section or my contact page.
WAVEFORM - VU METER - PEAK METER - RMS METER - PITCH MAPPING - SPECTRUM ANALYZER - FREQUENCY ANALYZER - SPECTROGRAM - 3D SPECTROGRAM - VECTORSCOPE - STEREO IMAGING - RESOURCES AND ADDITIONAL LEARNING MATERIALS
The first step when starting any project is to import the audio files into a digital audio workstation or DAW. My DAW of choice is Pro Tools for editing and mixing. Once I import the files into Pro Tools, a waveform view of each file is created automatically. These waveforms are actually graphs that display amplitude/volume over time. The waveform view provides a great deal of information to a trained eye. The first thing I look for when examining waveforms is clipped audio files, which is the main issue I encounter that causes major problems.
The waveform image above the title of this section is ideally how each audio file should look. Without listening I can tell there's not a great deal of excess noise, pops, or clicks. Every transient, or audio peak, is fully present. If I open up a session and see that all the waveforms look similar to that above image, I know it's going to be a good day.
Now take a look at the clipped audio waveform image. It looks as though someone took a scissors and cut off the top and bottom of the waveform. When the peaks of the waveform are clipped, this means that the mic/line input gain was set too high during recording. Overdriving an audio input in the digital realm causes digital distortion, which is extremely unpleasant to the ears and impossible to remove.
If you'd like to learn more about waveforms, SWPhonetics provides an in-depth explanation on their site. Click HERE to jump to their article.
(VU Meter - Peak Program Meter (PPM) - Peak Meter - RMS Meter - Loudness Meter)
Numerical meters are used throughout every stage of an audio project. They assist with setting proper levels during recording, balancing together different instruments during mixing, and checking the final audio levels during mastering. Arguably the most important visual tool in both the analog and digital domain.
There are two main styles of metering used. VU meters and Peak/RMS meters. VU meters or volume unit meters (pictured below) are commonly found on analog audio equipment such as: tape machines, large format recording consoles, and compressors. It's unlikely to see these meters outside of a professional recording studio, so we'll skip the details for now.
Peak and RMS meters are digital metering tools. RMS is an abbreviation for root mean square, which translates to the average level of an audio signal. A peak meter will display the loudest value of an audio signal. Peak and RMS meters are usually combined like in the below image.
Quick Note About the Colors
Since we can comprehend colors much faster than numbers, digital meters display a different color based off of the level of the audio. This makes a session of 20+ tracks much more manageable when trying to focus on the meters. Just to keep things simple; green is good, yellow is good, but red is bad. This is true in the digital domain.
Looking back to the image of the VU meters that I captured from my tape machine, you can see that up to 0 on the lower "normal" number display is black and 1 - 3 is red. In the analog domain, red is not necessarily bad. Now this may be confusing for those outside of the audio world. It basically comes down to digital vs analog distortion. Digital distortion, as discussed previously, is always terrible. Analog distortion is sometimes desirable. Additionally, the 0 on the VU meter is not the same level as the 0 on the peak/RMS meter. Further details are best left for another article.