Editing audio can be a fairly mind-numbing experience. But there is one rather abstract procedure which gives me a curious satisfaction: creating room tone.

Many recording sessions start or end with the engineer asking for a few seconds of silence while they record some—well—“silence”. This silence is technically known as “room tone” or “presence”. Here's why we do it...

The first thing to know is that every location has a distinct sound, or presence, even when nobody is making a sound.

Due to the way recording sessions take place, it's not necessarily a given that all stretches of silence will have been performed. Or even if they were, they might not be quiet (or smooth) enough. I'm mostly referring to those hushed moments between movements in classical music, but basically anywhere in a single work, recorded in the same space, where there are breaks or cæsuræ in the music. In such cases where there is no recorded silence or the silence is not silent enough, it must be somehow approximated during the editing phase.

It's not enough to simply 'fade to black' as that has a tendency to jarr, sounding like equipment failure. Rather, one must allow the decay of the instruments and room reverb to naturally disappear into the room tone; apply a cross-fade from there into our purposefully recorded section of room tone; and follow that with a cross-fade just before the next sound.

While this is standard practice in classical editing, I also like to liberally apply the technique to any acoustic music where the tracks on the album were recorded in the same space. For overdubbed, multi-tracked studio recordings, the rules are slightly different, but I still like to experiement with cutting in mic presence; an approach quite common in film audio dialogue editing and one which can really help maintain realism in vocal edits, for example.

It's such a curious little process, and you find yourself listening intently to silence, creating these little loops of nothingness, trying to ensure the silence is as smooth as possible. It's pretty trippy.

As an ironic addendum to this: the only time I ever blew a speaker was listening to silence. I had the gain up really high checking the smoothness of the silence when the computer unexpectedly crashed causing a spike in the audio output, and—BANG. All that lingered was the smell of toasted woofer.

I was clearing out a box of old hi-fi magazines recently. I haven’t so much as glanced at a hi-fi rag for a good few years, so it was quite a nostalgic trip leafing through the pages. It struck me how quaint and dated turn-of-the-century hi-fi seemed:

In the last twelve months, analogue cassette tape remains the most popular and affordable recording medium.1

That’s straight from What Hi-Fi’s 1999 Awards Issue. The same article goes on to note that MiniDisc is “the format of choice for music on the move”. Ha! It’s also interesting to learn about the Panasonic NV-HD640B: a “stonker” of a VCR (Video Cassette Recorder) that “proves there’s life in the old analogue dog yet”. Of course, this was when it cost upwards five-hundred quid for a decent “DVD-Video player”, as they so awkwardly called it in ’99. I’m genuinely shocked how quickly things have changed. It makes you wonder how music will be delivered 15 years from now. My guess? In edible form, perhaps as a topping on a Domino pizza. (Okay. I took that too far.)

What stuck out most, though, was not the dated technology, but rather the clichéd, jargon-loaded and hyperbole-laden writing. It seems that advertisers and reviewers alike will do anything to distract from the facts: speakers that “soar with high notes that radiate through the acoustic and then fall as her lyrics become laden with disappointment”2 amplifiers which “hang on to the rhythm of the sound for grim death”3 pre-amp cases made of acrylic to “avoid the stray magnetic currents caused by metal casework affecting the audio signal”4 there’s no end to the absurdity. And what about this beauty…

Right from the opening violin notes the improved focus and spacial definition is obvious. The acoustic space is blacker, with a quieter background which makes the side and rear walls of that space much more apparent. The texture of the insistent notes is also more obvious, as is the sweep of the awakening orchestra as the opening bars pass across the strings, the punctuation of the percussion that much more emphatic.5

What’s it describing then? A beautiful new concert hall? Perhaps a state-of-the-art sound stage? Nope. This is describing a mains cable. Ah, but not just any mains cable. This is a two-meter, Nordost brand £900 mains cable. You see, it’s the two fat zeros after the nine in the price which makes it so good, which “makes the voice more convincing and intimate, giving the song a new focus and core”. Of course, to reap the most benefit you need one for each component in your hi-fi.

Shame on you Hi-Fi+, and shame on the article’s author and repeat offender Roy Gregory. (EDIT: Gregory stepped down as editor of Hi-Fi+ in early-2009 to become head of marketing at—you guessed it—Nordost.)