But our brains also use other cues to determine distance. For example, human hearing excels at matching a sound with the echoes and reflections it causes, to localize its source. And we can apply this principle to add realism when creating the sound stage in a mix.

The Speed of Sound

Consider this picture, and the accompanying audio samples below.

In the scenario illustrated above, sound from the guitar reaches the listener almost immediately, whereas the reflections off the rear wall make a 40-foot round trip, and therefore arrive 40ms later. (Sound travels approximately 1 foot per millisecond.) With the drum kit, on the other hand, the direct and reflected sounds arrive at almost the same time.

The series of events goes something like this:

Our ears and brain are sensitive to these differences in sound arrival time, and use the information (along with other cues, like volume) to judge where a sound source is located in the space around us. Our brains know that sounds and reflections arriving together at our ears must have originated close to a wall, where sounds that arrive much before their reflections must be close to our ears.

Hear it in practice

Here are two short instrumental samples, both mixed from the same raw tracks, to illustrate how this can apply in a mix.

In the first sample, I’ve placed the drums closer by adding a delay between the direct drum sound and the reverb, so the reflections arrive 40ms later than the direct sound – which tricks our ears into hearing a 20ft distance between the drums and rear wall, as with the guitar in the above diagram:

In the second sample, I’ve simulated moving the drums further back by having the direct sound and reverb occur together, both 40ms later than the guitar.

Note that the levels are the same in each clip. I changed the delay times only, to illustrate the effect.

Issues

Caveat: The illustration above is grossly over-simplified. Sounds in a real room reflect off all the walls and surfaces, not just the rear wall. And our ears depend on much more than just timing differences to determine distance. But for the technique at hand, those complications generally aren’t important. The idea here is to trick listeners’ brains by exploiting a property of their sense of hearing, and whether there’s one wall or 4, human ears and brains interpret reverberant sounds the same. (If your listeners are mostly non-human, then all bets are off.)

Implementation: In Sonar, I configure sends (i.e. busses) with delay plugins for each delay time that I need, and I route tracks accordingly. But any platform that allows bussing or routing the signal can accomplish the same end result. So long as you can independently control the delay on the direct sound and on the reverb, you can manipulate the relationship between the two as described above.

Other levels: In practice, you’ll also reduce the level of the drum kit somewhat to make it sound more distant, and adjust the reverb level as required to make the effect more obvious.

Pre-delay

As an addendum: Most reverb units and plugins have a pre-delay setting for controlling the delay between the input sound and the reflections it generates. Pre-delay serves exactly the same function as placing a delay between the direct sound and the reverb. In essence, it “moves” the sound further from the simulated reflecting surface. So if your reverb unit or plugin supports pre-delay, you can accomplish much of the above technique without a separate delay plugin.

And remember this simple guideline when using reverbs for realistic 3d sound stages: To bring a sound forward in the mix, increase the pre-delay.

See Also: Reverb on kick drum, Reverb possibilities

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Some engineers even argue over which type of dither is best, claiming this algorithm is more airy sounding that that one, and so forth. But just because everyone believes this, does that make it true?

That quote comes from Ethan Winer’s great summary of his position on the matter – he’s squarely in the “dithering is usually not needed” camp.

I tend to agree with Ethan. Responsible mixing engineers don’t apply processing to a mix if they themselves don’t hear the effect of the processing. Simply put, if you can’t hear a difference, don’t make the change.

Unmitigated awesome: Daved Lee Roth’s vocal track from Runnin With The Devil, solo’d.

Converting Ikea bedside tables into studio racks: “the Rast bedside table makes a snug rack for music machines.”

Two unrelated sites feature famous songwriters discussing what went on behind the scenes as they wrote:

First, Joni Mitchell on the writing and recording of her most recent album:

When I recorded it, I was sick so a doctor prescribed some penicillin, which I had an allergic reaction to. I was delirious, stressed out, and we worked all night long. I was so delirious that I was playing way back on the beat… [I]n January 2007, I had demos of the Shine songs with me and played them to some friends at a party afterward. James Taylor told me that he had to play on this song. I wasn’t sure if anyone could because it was created in such a rare spirit. But James came in anyway and I asked him to play short figures like a saxophone. So you can hear fractions of James’ guitar playing here.

Jim Vallance’s site has some fantastic insight into the mind of a professional songwriter. Jim, who’s worked with Aerosmith, Ozzy, Bryan Adams, The Scorpions, and Thornley, meticulously lists every song he has ever written. The site is full of anecdotes and details about his creation process.

On our very first basement demo of “Summer of ’69″ we started the song with the 12-string riff, exactly like the “break down” section in the middle of the song … but on subsequent demo’s we replaced the 12-string with a chunky 6-string intro. In fact, we toiled over the musical arrangement for several weeks, maybe longer. We recorded the song three or four different ways, and we still weren’t convinced we had it right! Bryan even considered dropping the song from the Reckless album.

Now, 20 years later, when I hear “Summer of ’69″ on the radio, I honestly can’t remember what bothered us.

The story saddened me deeply. I admire Martin and his accomplishments, so I empathized with his loss. But I also hope to work with music all my life, and the image of myself in Martin’s position, forced to retire from the work I love, is unappealing to say the least. More pragmatically, though, the odds are I’ll suffer some age related hearing loss anyway, and since gene therapy hasn’t progressed beyond the guinea pig stage, why would I take any chances with my hearing?

This is all fresh in my mind because of a feature in last month’s Mix magazine, Bring Down The Noise. If you haven’t spent much time thinking about the importance of your hearing, I urge you to read the article:

It’s a vicious cycle: Those who depend on their hearing to do their job put it at a risk by doing their job, day after day… But unlike a job foreman or the guy at the firing range, audio engineers are a sound-savvy group and have a pretty good idea of what they are getting themselves into.

So it should be a no-brainer: Engineers rely on their ears. The damage is preventable. Their hands are on the volume controls. Why isn’t anyone turning it down?

Why indeed? Preventing hearing loss is so easy: Limit your exposure to loud sounds. As musicians and mixing engineers, we even have an advantage over others who work in noisy environments. The volume knob!

The best defense

All musicians are at risk for hearing damage, not just live rock performers. So we all need to take some precautions. Experts commonly recommend a few easy steps that musicians and recording engineers should take to prevent hearing loss:

• Wear ear plugs like they’re going out of style. (I know they were never in style.) Disposable earplugs are cheap, so keep them everywhere. I have a pack in my studio, another in my gig bag, and a third in my glove box.
• Have your hearing tested every few years. We all fear the hearing test, or more specifically the possibility of failing. But it really is better to know if you’ve done, or are still doing, damage. The test takes half an hour. And for a recording or mixing engineer, there are few sounds sweeter than the audiologist’s voice announcing “your ears are fine.”
• Take breaks while you’re mixing. Your ears adapt to music at any volume, and over time loud gradually seems less loud. Take breaks to keep your ears honest.
• Realize it’s never too late. If you’ve already got ringing or some other form of tinnitus, you can at least stop it from getting worse. Even if you have a high frequency notch in your hearing, you can still learn to compensate, and produce good mixes. But if you take a “damage is already done” attitude, it’s a safe bet you’ll end up like George Martin.

And one last tip, specific to mixing engineers:
Be extra careful if you mix with headphones:

Another hearing phenomenon that seems to be more noticeable with headphones is a decreasing sensitivity to sound levels over time, as the ears adapt to loud sounds. The listener perceives a gradual drop in loudness even though the volume control setting hasn’t changed. The acoustic isolation of headphones tends to highlight this dulling effect. It is all too easy for headphone listeners to turn up the volume to the point where hearing is at risk. Interestingly, most people find it difficult to distinguish between 85dB and 100dB SPLs, despite that the latter is more injurious to hearing…

Finally, while it’s obviously no substitute for having your ears checked by a professional, you can test your ears’ frequency response right now using your computer and a pair of headphones. (And there’s no way to fail the test!)

There may be slightly more to it, however. Lifehacker recently featured a list of body hacks, and it included this great tip about using our ears:

If you’re stuck chatting up a mumbler at a cocktail party, lean in with your right ear. It’s better than your left at following the rapid rhythms of speech… If, on the other hand, you’re trying to identify that song playing softly in the elevator, turn your left ear toward the sound. The left ear is better at picking up music tones.

Neuroscientists have learned that because of the brain hemisphere to which each of our ears is connected, our left and right ears hear things differently. The right ear responds more to rhythm and speech, while the left ear is more attuned to music.

From a study published in the Canadian Journal of Experimental Psychology:

This finding provides support for claims of a right-hemisphere bias for the processing of melodic contour… In the present study, we sought to determine whether short tone sequences presented monaurally (to one ear at a time) are processed differentially by the two hemispheres. Studies of auditory processing often indicate that linguistic and musical stimuli are processed preferentially by the left and right hemispheres, respectively

This has an obvious implication for mix engineers: If you favour one of your ears, it could affect your mix decisions. Dye’s trick of checking a mix for mono compatibility could yield different results depending on which ear you stick your finger in!

Of course, you can use this to your advantage too. For example, when you need to make a decision about a mix’s rhythm elements, you might find it easier if you listen only with your right ear.

Practice and experience are the sure-fire methods, of course. But if your recording environment lets you invert the phase of a track, there’s a simple trick you can use to make small changes more obvious.

Because of phase cancellation, when you mix a track with a phase-inverted copy of itself, the two tracks cancel each other out and you hear silence.

However, if you then make a small change to one of the tracks, they’ll no longer cancel each other completely. Instead you’ll hear the parts that don’t cancel out, or effectively the difference between the two tracks. You can use this to hear when an effect has altered the sound of a track by even the smallest “just noticeable” amount.

The concept is straightforward: By mixing the effected track with an inverted copy of the original, you’ll hear the difference introduced by the effect.

And the process for applying this concept is straightforward too: Duplicate the audio track, and invert the phase of the second track. (Like this, in Sonar)

Note the phase-invert button on the second track has been activated. In most DAWs, including Sonar and Cubase, the phase-invert button is denoted by the greek letter phi. As stated above, if you play the two tracks at this point you’ll hear nothing, since they cancel each other out.

Now, on the first track, add the effect you wish to monitor. Adjust the effect a small amount. As you raise its level, the two tracks will increasingly differ, and since they no longer completely cancel each other out, you’ll hear that difference.

Further, you can mute the second track to remove the phase cancellation altogether, and hear how the first track sounds with the effect applied. With some practice, flipping between the original track, the effected track, and the combination which highlights the difference, you’ll get better at judging when an effect is just noticeable.

Here’s a contrived example illustrating the process I used to convince myself that Magneto, a tape emulator, was in fact altering the sound of the tracks I applied it to. (Here’s a screenshot of the Magneto settings I used.)

The clip contains 3 repetitions of a riff, as shown below. First, it’s the original riff. Then, with the effect applied, we hear the “phase cancelled” difference between both tracks. (So clearly, Magneto does something!)

And finally, we hear the effected riff, with no cancellation.

One last note: In the unlikely event that your DAW doesn’t have a phase-invert button, Flipper is a free VST plugin that will do the job for you.

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In almost every situation, I would be at LEAST 4 feet further away with the mic than in those pictures. the harshness comes from the fact that the instrument was never designed to be heard from that close.

Do you need your ears cleaned? An audiologist chimes in:

Someone mentioned ear candles. I would absolutely, under no circumstances EVER use an ear candle. They are a hoax. We did some experimenting with these in graduate school and there is no way you can produce enough “suction” to remove anything from the ear canal with them. At best they are a waste of money and at worst they are potentially dangerous.

Tracking a 5-string bass shouldn’t be any more difficult than a bass:

if you can’t plug the bass into any old di and get a decent to good sound with no fiidling, the problem is with the hands and/or the instrument they’re holding. if you got a decent sound coming off tape (oh my, how tape takes care of so many bass problems), but when you drop it in the mix it disappears or plays hide and seek, the problem is likely in the arrangement and/or the part. that doesn’t mean that the solutions to the above problems can’t be found somewhat or even mostly in gear and tweaks, because a talented set of hands and ears can work miracles. but ime even the best miracles fall short of what happens when a great part is well played and mixed into the right arrangement.

This site allows you to measure equal loudness contours–the frequency response of your own ears. The flash script allows you to play sound files with a range of frequencies and sound levels with the click of a mouse.

Test the frequency response of your ears