It’s been a great month here on Designing Sound! We took a gamble in November with the new monthly features format, and it’s been paying off in spectacular fashion. This site would not be so special without the support and contributions of the community it serves. A hearty round of thanks goes out to this month’s guests:
Tomorrow begins plug-in month. That’s a little vague, I know, but the full description of how and what we’ll be exploring is on its way. If you have something you’d like to contribute, don’t hesitate to get in touch. As you may have noticed, guest contributors are in good company!
Guest contribution by Cormac Donnelly
I am, at heart, a techno-nostalgiast and I’ve worked with tape machines of one kind or other for most of my career. When I sold my 2” multi-track, in 2010, I resolved almost immediately to get myself another tape machine (albeit something a little smaller than the 250kg Otari I had just parted with). A few weeks later, I found myself owning two portable Nagras. I have since realised that the only reason any one person should own two Nagras is so they can indulge in a spot of worldizing.
Guest contribution by Michael Theiler (Kpow Audio)
Situating an Ambience
When creating ambiences for games (this applies equally to film), I am striving to make them blend into the background and not mask any important in game sounds. For most ambiences, these are the most important qualities that I am attempting to resolve.
In order to achieve this, I need to firstly focus on the repetition and timing between audio occurrences in the sounds. This means spacing sounds, and adding and removing sound occurrences in my audio sequence. I then work on the frequencies in the sounds, using equalization to mold them into the right sound. Finally, I work on their sound propagation and the sound of the space in which they are to inhabit. These are the steps necessary to mould sound into something suitable for the space. Just adding reverb is not enough – the sound needs to be purpose built for the space’s reverberation and delay treatment.
With growing computing power over the last decade, convolution plugins have become commonplace. Some of the most common ones include Audio Ease Altiverb, Logic’s Space Designer, Avid TL Space, Waves IR-1 and McDsp Revolver. They are usually packaged with large and useful libraries of impulse responses (more on what all this means below), but what makes them really powerful is the fact that it is quite easy to record and use your own impulse responses. This not only helps ‘personalise’ your mixes, but is extremely useful in post-production and in the design of new sounds.
Each of the above mentioned plugins need slightly different techniques for creating a custom library of impulse responses. This article is a description of the general concepts behind recording good impulse responses and should be easily adaptable to any convolution/de-convolution tool.
What is convolution?
Convolution is the process where a single sample of a sound is multiplied by every sample of another sound. It is different from the plain multiplication of two sounds where a single sample of the first sound is multiplied by the corresponding single sample of a second sound.
Curtis Roads (The Computer Music Tutorial) describes convolution as:
Convolution of two audio signals is equivalent to filtering the spectrum of one sound by the spectrum of another sound. Convolution of spectra means that each point in the discrete frequency spectrum of input a is convolved with every point in the spectrum b.
Tor Johnson over at New Sound Lab has recently released “NSL009 Spring Reverb.” From Tor’s description:
“This library features recordings created using a “Knas Ekdahl Moisturizer“, a boutique spring reverb effects unit where three reverb springs are exposed, allowing them to be hit, played, and manipulated in real time. The unit also includes a multi-mode analog filter, and when combined with the playability of the springs, opens up many sound creation options.”
This collection of 872 sounds is a fantastic mix of scrapes, drags, plucks, hits and rattles: