Get the Hiss Out in Soundtrack Pro

In a time where so much of what a lot of us do is 'in the box', it can be easy to forget that there was a time when noise reduction was a necessity. I'm not even just talking about the inherent noise that was present in tracking to tape, but the instruments themselves sometimes had pretty bad signal to noise ratios by modern standards (The Yamaha DX-7 was notoriously noisey, for example...).

Even if you don't use any hardware instruments or record vocals or guitars, chances are there is still going to be a time where you have a sample or recording that has more noise in it than you would prefer. Fortunately, many audio editors come equipped with tools to deal with this, and if you are careful in your settings, there are very few bad side effects.

Today I'll be showing you how to do this with Apple's Soundtrack Pro.

1. The first thing to keep in mind is that we will need a brief sample of the noise by itself, so don't trim the audio down, just open up the raw file that needs reduction. Especially if you are recording, say, multi-samples of a vintage synth, you should apply any noise reduction to the entire file at once before you edit them into their respective parts because you want the sounds to be consistent from key to key.

2. So load up your sound and isolate a section where there is just the noise by itself. Click and drag on the waveform to highlight some of it. It doesn't have to be super long, but nor should it be excessively short. A second or two should suffice.

3. Go up to the Process menu and select Process->Noise Reduction->Set Noise Print. This is giving Soundtrack a 'fingerprint' of the noise itself, so it knows what parts of the audio to reduce.

4. Next, select your entire audio file so that the noise reduction will effect all of your audio. Go to the Process menu and select Process->Noise Reduction->Reduce Noise... a new dialog window will open with a range of settings for you to adjust.

5. Even the best noise reduction systems can effect audio adversely if settings aren't careful, so it's important to be able to hear what we're doing as we make adjustments. You'll notice at the bottom left hand corner of the dialog window is a volume slider and play key. This will continuously loop whatever audio you have selected (make sure to select a section that has the synth/voice/guitar/etc in it for this), so you can hear any ill effects and avoid them.

6. The slider you see at the top is probably the most important one - the Threshold slider. This basically lets you tell Soundtrack where the noise floor is in your track. You're defining the level at which you want Soundtrack to start doing its thing. The wrong setting here can adversely effect the audio you actually want to keep, so take your time and listen to the preview loop as you tweak it. If your settings are too extreme here the 'good' audio portion of your track will start to sound grainy, dull, and distorted in an undesirable way. (At least for now... it will probably be the next big trend in dance music in a week or so...)

7. Below this is the Reduction setting. In most cases, 100% is probably fine, but if you find you have a pretty decent Threshold setting that's altering the good audio a little too much, you can back off on the amount of Reduction here and correct that.

8. Below that is another 'tweaking' parameter: Tone Control. This allows you to tell Soundtrack which frequencies are more important to you to preserve: the low ones, the mids, or the highs? Soundtrack will then bias the frequencies it's removing from your signal to have the least detrimental effect to the frequency range you define.

9. There's one more feature here that will help you fine-tune your settings: the Noise Only check box near the preview player. Selecting this will switch the preview audio from being what the file will sound like after noise reduction to being JUST the part of the signal you are removing. If you hear too much of the 'good' signal here, your settings might be too extreme.

10. Once you have settings you are happy with, hit the 'Apply' button and Soundtrack will apply the noise reduction to the file.

It's not always possible to get a totally pristine result depending on the nature of your recordings, but you should be able to hear a pretty significant difference. Consider, too, that perhaps noise isn't always a terrible thing. It can add to the character and warmth of a recording sometimes. But if you do have that one bit of noise in an isolated part of your song that is driving you nuts, now you know how to get rid of it!

Time-Stretching in Apple Soundtrack Pro

Although the theory behind it was developed back in 1978, time-stretching - the ability to change the length of a sample without effecting the pitch - didn't really appear on much of a practical level for most of us until the late 80's/early 90's. This ability, which most of us take for granted now, totally revolutionized sampling and helped spawn the breakbeat era. Finally, musicians could speed up or slow down a drum loop without the dreaded munchkinization/darth vaderization of their sound. There were obviously practical limits to this technique, and more extreme values led to long, evolving grainy washes. As with many things, at first this was avoided, but as the technology became old hat, people started to exploit this effect, and indeed, it can be a really cool source of otherworldly sounds.

Most audio editors have time stretching/compressing abilities in one form or the other, but I've personally never worked with one as easy as Apple Soundtrack Pro (which is included with Apple Logic Studio). Here's how to do it.

1. Open up a piece of audio. It can be literally anything, although you will discover the characteristics of the sound you choose has some influence on your final sound. But for now, just load up anything and use the arrow tool to select about a one second snippet. Hit Apple-C to copy your selection to the clipboard.

2. Select File->New->Audio File to create a new, empty file.

3. Soundtrack won't let you stretch beyond the original total file length, so we're going to insert silence to extend the file length of our new file beyond the length of our audio snippet. Select Process->Insert->Silence... and when the dialogue box appears, click and drag your mouse over the time window to increase the length of the inserted silence to about 1 minute.

4. Hit return on your keyboard to return the playhead to the beginning of the file and hit Apple-V to paste your audio selection at the beginning of your new file.

5. You'll probably barely be able to see it because it's so small compared to the total file length, so use the zoom slider at the bottom right hand corner of the window to zoom in. Once you can see the audio easily, use the arrow tool to select just the audio portion (and none, or as little silence as possible). Now zoom back out again so you can see the entire length of the file, but not so far that you can't still see your selected audio.

6. Select the time-stretching tool from the tool bar in the top right hand corner of the window. It's the fourth tool from the left. (I've circled it in the picture at the top of this article). Place the pointer on the right-hand edge of your audio selection and you should see the marquee change to the time-stretching icon. Click and drag to the right. You should see a 'ghost image' of the waveform being stretched until you release it. Soundtrack will only allow you to stretch by a certain percentage at a time, so at a certain point, you won't be able to move the pointer any furhter. Go ahead an let go and wait for the audio to stretch. Now repeat again, dragging the right hand part of the selection as far as it will go to the right. Keep doing this until you've filled the entire minute. Keep in mind the longer you stretch your file, the more calculating the program needs to do, so each time will take slightly longer.

7. Now play back your grainy, alien soundscape by hitting the spacebar.

8. This is pretty cool in itself, but take it to the next level in your DAW of choice and throw some plug-ins on it.... filters, delays, big reverbs... anything that sounds good. Or better yet, throw it in your sampler of choice for further abuse. Before you know it, you have the perfect eerie intro to that track you've been working on. Here's a quick and dirty example:



Note that most DAWs have time-stretching abilities built-in... I just find the way Soundtrack implements it a bit more fun to use, especially for extreme settings.