Stacking and Multi-band compression

Stacking compression
You may have noticed when you were playing around with compression in the last setting that a little bit of compression sounds good, but too much starts to sound noticeable. Sometimes, however, you may need a little more than light compression. The problem is that if you use a heavier setting, the effect starts to become too noticeable. One way around this is to stack your compression effects.

It's a really simple concept; apply a light compression across your entire file, and then apply another light compression. Lightly compressing the material twice is a much subtler effect than heavily compressing once. In fact, this approach is very common in recording applications. Audio engineers lightly compress material that is being recorded, to provide a little control over levels. Then, after the material has been edited, they apply additional compression to give the program that extra bit of presence.

Another approach, used in multi-track recording situations, is to use different compression effects on different tracks, and then to have a limiter placed across the master mix, to make sure the final mix never goes into distortion.

Multi-band compression
All the compression we've been talking about up to this point has been compression that analyzes the entire frequency range when determining what has exceeded the threshold. There are specialized compressors that break the frequency range into a number of different bands and then compress them all individually. Radio stations use ridiculously expensive multi-band compressors and set them up to try to get a unique, signature sound. (All they're really doing is competing to see who sounds loudest.)

One area where multi-band compression can be incredibly useful is as a corrective measure, in particular to deal with microphone pops and sibilants problems. In the EQ section, we discussed how you could deal with pops and "ess" sounds by turning down certain frequencies at the instant the problem syllable appears. A multi-band compressor does this for you automatically.

Figure 1 shows Sony Sound Forge's multi-band compressor, using a preset called "Reduce plosives and sibilants." It's using two bands, both of which have very fast attack and release times, because we want the compressor to react immediately. Band #1 is set to low shelf mode, meaning it monitors all frequencies below the shelf frequency, which in this case is 600Hz. Band #2 is set to notch mode, with a moderate Q of one octave, centered on 5KHz. When I preview audio, I can see the second band being compressed when the narrator pronounces "ess" sounds. Because my narrator hasn't popped the mic, the top band doesn't do much of anything. If you have a guest who has a problem with sibilants, you can use the de-ess preset (yes, that's the technical term for this) to get rid of the problem. Fabulous.


Figure 1: Using Sony Sound Forge's multi-band compressor to fight pops and sibilants

Compression: A step-by-step example

Now that you know a little bit about how compression works, it's time to play around with it to see how it affects the sound of your podcast. For this example, we'll be using the compressor that comes with Audacity.

1. Open Audacity, and open your podcast file.

2. Select the entire file by pressing Ctrl-A (Opt-A on a Mac). Remember that Audacity doesn't expose the effects until you highlight a section of your audio.

3. Select Compressor from the Effect menu. This brings up the Dynamic Range Compressor window, as shown in Figure 1.


Figure 1: The Dynamic Range Compressor in Audacity

4. You can see in Figure 1 that the default settings for the Audacity Compressor is a 2:1 compression ratio, a -12dB threshold, and a .2 second attack time. (This plug-in doesn't have a release time setting.) In fact, this is a nice moderate setting that may work just fine for your content. However, you may want to experiment with the settings to see what changing the threshold, ratio, and attack times do to the sound of your file.

Audacity's Dynamic Range Compressor settings are adjustable in increments. For example, the ratios are variable in .5 increments (1.5:1, 2:1, 2.5:1, and so forth), and the attack times in tenths of seconds. Try changing the compression settings to a 4:1 ratio and a .1 second attack time. Preview the audio. Hear a difference?

In fact, 100 milliseconds is really too slow of an attack time. To hear why, try changing the threshold to something really low, say -30dB. Preview the audio. Hear that? The audio starts off loud, and 100 milliseconds later the compressor kicks in. The compression effect is audible, because the attack time is too slow. However, if you raise the threshold up to say -15dB, the effect may not be as audible. You should be able to find a threshold that works in conjunction with the sluggish attack time.

How compression works

How compression works
Most compressors offer the same basic controls, which allow you to set the following:

Threshold: Where the compression effect kicks in

Ratio: The amount of compression applied above the threshold

Attack and Release times: The length of time after the threshold is crossed that the effect is applied and removed

Figure 1 illustrates what different compression curves look like. Looking at the curve, you'll see that signal levels below the threshold are unaffected, and signal levels above the threshold are attenuated. The higher the compression ratio is, the more attenuation. When the compression ratio is high, it is known as limiting, because it more or less prevents the audio from exceeding the threshold.


Figure 1: Compression curves with different compression ratios

Setting a threshold
To illustrate how different threshold settings affect the output, let's assume that we're working with the audio file illustrated in Figure 2. We can see that this file has peaks as high as -2dB, but the bulk of the file is below the -10dB mark. If we want to compress this file lightly, we should set a threshold in the -6dB to -10dB range. Figure 3 illustrates compression applied to this file using two different thresholds, -6 and -20dB.


Figure 2: The audio file from Figure 7.5 after compression using a threshold of a) -6dB and b) -20dB


Figure 3: The audio files from Figure 2 after applying compensating gain

What is immediately apparent is that the file in Figure 2b has been compressed far more heavily than Figure 2a. We need to apply some gain to restore these files to their former levels. Figure 2b has far more headroom, so we can apply much more gain. After applying gain, we end up with the files illustrated in Figure 3.

These files are both much louder than the original, but if you look closely at the figure on the right, the entire file is loud. It doesn't have any dynamics left, because the dynamic range has been compressed. To be honest, this file might be a little too compressed. Files that have been over-compressed are fatiguing to listen to, because EVERY SINGLE SYLLABLE IS LOUD. Think of drive-time radio programs; they're highly compressed, because the DJs are going absolutely nuts in the studio. The idea is to compete with all the noise of traffic and to keep you awake on your drive to and from work. But this is not the type of programming you really want to listen to all day long (see the "Compression: How Much Is Enough?" sidebar).

If your original audio file is well recorded, you should have peaks in the -3dB to -6dB range. Choosing a threshold in the -6dB to -10dB range is a safe starting point. This way, you're only compressing the loudest sections of your file, leaving most of your file untouched. If you find yourself dropping your threshold much below that, you may consider revisiting your signal chain to figure out why your recording is so quiet in the first place.

Setting a ratio
The ratio setting determines how much compression is applied over the threshold. For example, a 2:1 compression ratio means that for every 2dB by which the incoming signal exceeds the threshold, only 1dB of gain is applied. Ratios up to around 4:1 are mild and can be used safely, provided you set a sensible threshold. Ratios in the 4:1 to 10:1 range are fairly heavy and should be used with caution. Any ratio over 10:1 falls into a special category known as limiting.

Limiting can be useful as a preventative measure, but it isn't appropriate as your main form of compression. For most applications, start off with a ratio of 4:1 and experiment with using slightly more or less until you achieve the effect you're after. In particular, voices are particularly compression tolerant, so if you don't have any music in your podcast, you may be able to use more compression (see the "Compression: Voice versus Music" sidebar).

Setting attack and release times
The attack and release times control how quickly the compression effect is applied to signals that exceed the threshold you set, and how quickly the signal level is returned to the original input. For most content, you want a quick attack time, so signals that exceed the threshold are immediately attenuated. For the release time, you want something a bit longer, so the sound doesn't abruptly get returned to the original level.

This is fairly self-evident from the attack and release controls. The scale on the attack control knob generally is in milliseconds, and the scale on the release knob is in seconds. Start with a quick attack, say 10-20 milliseconds, and a gradual release around 500 milliseconds. These settings should work for most podcasting content, but don't be afraid to play around with your compressor to see how these settings affect the compression.

Compression : Why use compression?

Compression
Compression is a form of dynamics processing, meaning that it deals with the overall levels in a file. Compression automatically turns down sections of your audio file, based on settings you specify. Think of it as an automatic volume control. In fact, you may have run into Automatic Gain Control (AGC) on a piece of hardware you own. Many portable tape recorders have an AGC circuit built in to the microphone. This is a fancy marketing term for a compressor. The AGC circuit ensures that all sounds are picked up and that sounds don't get so loud that they distort the microphone input.

Most compressors offer a number of controls that enable you to set where the compression effect kicks in and how drastic it is. But before we get into the details of how compression works, let's talk a little bit about why compression is useful.

Why use compression?
At its most basic, compression is useful as a safeguard against distortion. A compressor automatically adjusts the signal level when it exceeds a certain threshold, so that a guest who suddenly gets excited won't send your levels into the red. For this simple reason, compressors are very useful in live situations, when you may not be able to control situations as tightly as you'd like to.

Compression also is useful when working in lower fidelity environments, because it allows you to match the dynamic range of your production to the available dynamic range of the equipment on which it is played back. CD-quality audio has a very large dynamic range, and provided you're listening in a quiet environment, you can hear very quiet sounds as well as very loud sounds coming off a well-produced CD. This simply isn't the case for most podcasts.

First, most podcasts are played back on desktop systems, very often in slightly noisy environments. So if your podcast has very quiet sections, people will have a hard time listening, because they'll either have to turn the volume up temporarily or shush the people around them. And if you're encoding at a lower bit rate (96Kbps, 64Kbps, or even 32Kbps), the dynamic range simply isn't that great. The encoding software uses volume as a determinant of importance, so quieter sections won't sound as good as the louder sections.

If the quieter sections of your podcast are going to be difficult to hear, then you want to turn those sections up, right? Sure you do. You want the overall level of your file evened out, so you don't have large differences between the loud sections and the quiet sections. You want the dynamic range compressed. This is precisely what a compressor does.

Figure 1 illustrates the dynamic range and headroom of a file. We'd like to turn up the quiet sections of this file, but at a certain point, the louder sections will go into distortion. Using a compressor, we can turn the file up and ensure that the loud sections don't go into distortion, because the compressor turns those sections down automatically.


Figure 1: The dynamic range and headroom of an audio file

The final reason to use compression is because we're used to hearing compressed audio on all the traditional broadcast mediums. Radio and television use compression liberally. This is partially for the protective reasons discussed previously, but also because of a particular side effect of compression. Compression tends to make things sound fuller, because it brings up the bottom end of the audio signal. Between the protective qualities of compression and the added warmth, this combination is hard to beat.

Advanced EQ techniques

EQ also can be used as a corrective measure. The techniques described in the preceding sections aimed to improve the overall sonic quality of your audio by focusing on what you wanted to be heard. You also can use EQ to remove extraneous noise that you don't want in the file.

Clearing up noise
If you recorded your audio in a noisy environment, you can use EQ to get rid of some of the worst noise. First, roll off all the low frequencies. You should do this regularly to all frequencies below 60Hz, because they're generally not reproduced by most systems. You can roll off more if you're dealing with serious noise. For example, traffic outside a busy city window will be audible as a steady low rumble, with the occasional siren or horn. If you roll off more of the bottom end, the sound of the traffic will be less audible.

Similarly, you can roll off high frequencies if you have noise problems such as air conditioning or tape hiss. In the preceding example, we boosted all frequencies above 5KHz to give the file some air; clearly, this is not something we'd want to do if we were in a noisy environment. Of course, we could have used the shelf to roll off all high frequencies above 8KHz or so and added a slight lift around 4–5KHz. Very little important voice information is in the range above 10KHz, so if you have noise problems, you can safely roll this off without any damage to the intelligibility of the audio.

Of course, in extreme situations, you can get pretty savage with EQ if necessary. For example, sometimes news reporters outside during a storm sound like they're talking through a telephone line. This is because the audio engineer at the station has rolled off all low frequencies and high frequencies, leaving just the mids.

Pops
Sometimes, a pop sneaks into your audio file, even if you're using a pop screen. If you zoom in to your audio file and look at the offending pop, you'll see that it's a very brief, very loud low frequency burst. You can highlight the offending word (or even syllable) and roll off the offending bass frequencies, as shown in Figure 1.


Figure 1: A pop is visible as a short, loud low-frequency burst, which can be fixed with EQ.

Experiment with different amounts of roll-off at different frequencies. You'll find that if you roll off too much, you get rid of the pop, but the result may sound unnatural. Find a good balance between removing as much of the offending pop as possible, while retaining the natural feel of the original.

Dealing with sibilants
Some people have a problem with sibilants, which are consonants like the letter "s" ("d" and "t" can also be a problem but usually nowhere near as much) that contain a burst of high-frequency information. This is audible as a whistling or, well, an "ess" sound. A little of this is natural, but too much is annoying. Some people actually whistle when they pronounce these consonants, which is an extreme version of the same problem. Because this is usually a very localized problem, it can be dealt with using EQ.

Sibilants usually are most prominent around 5KHz. Just like the preceding example where a word was highlighted and bass frequencies were rolled off to get rid of a pop, you can highlight a word and try to cut the offending frequency. Dealing with sibilants is more troublesome than popping, because our ears are very sensitive to high frequencies, and even if it's only a momentary change, our ears may notice that the sound has changed. Not only that, but if someone has trouble with sibilants, it usually manifests itself throughout the entire interview — and the letter "s" is very popular in the English language. In general, if you want to deal with sibilants, you should use a de-esser. That's a fancy term we audio engineers made up to describe a "frequency dependent, side chain controlled compressor." De-essers are explained in the compression section, which comes next.

EQ: A step-by-step example

This section steps you through the EQ process, with both graphic and parametric EQ. We'll assume that this is a male voice track that needs a little bit of sparkle. We're trying to do the following:

- Add a bit of warmth to the bottom end.

- Add a little clarity to the midrange.

- Give the vocal a bit of air, a little extra shimmer.

We're going to assume that you're using a software equalizer, though there's no reason that this couldn't be done using a hardware EQ. Also, the frequencies we're choosing in this example may not be the best frequencies for your audio, although they're probably a good place to start. Remember: Use your ears:

1. First, roll off the extreme low end. Chances are good (unless you have an extremely deep voice) that there is no information down here, except for possibly some room noise. Let's roll off everything below 60Hz.

On a graphic EQ, push down the faders below 60Hz. If you have more than one, start off gradually, rolling off about 3dB at 60Hz and then increasing the roll-off with each lower frequency.

On a parametric EQ, choose a high-pass filter at 60Hz and roll it all off. Shelving EQ has gradual roll-off built in.

2. Listen to your audio. You shouldn't hear much of a difference, if any. That's fine. You may hear a slight clearing up of the sound, and if so, that's even better.

3. Next, work on the midrange, because it's the most important. To give a voiceover a slight lift, you can boost the upper mids in the 2 – 4KHz range.

On a graphic EQ, pick a frequency in this range and boost it significantly, say 6-10dB. Preview your audio. Return that frequency to no gain, and try boosting the frequencies on either side, previewing each time. When you find the frequency that sounds best for your content, boost it 3dB and then boost the frequencies on either side 1.5dB, so there's a nice gentle lift. Preview the audio, and make sure it sounds good.

On a parametric EQ, choose a narrow Q and boost a frequency in the 2 – 4KHz range. Preview your audio. Try moving the frequency setting up and down, until you find the right frequency. Preview the audio each time you change the frequency. After you settle on a frequency, widen your Q to approximately 1.5. Boost 3dB, and give your audio one last preview to make sure you're doing the right thing.

4. Now listen to the low mids. The low mids are roughly where the sounds "er" and "uh" live. (If you've ever seen a sound check before a live gig, you'll hear the audio engineer making these sounds in the mics to check the EQ.) These frequencies give our ears information about the size of a room. You can often clear up a mix by cutting here, but be careful: You can make your audio sound too thin if you cut too much.

On a graphic EQ, you can experiment with cutting around 300Hz. You can do the same on a parametric EQ, with the added benefit that you can make the Q very narrow, to avoid thinning out your mix too much. Be sure to preview your audio to make sure you're making it sound better and not too thin.

5. If you're worried about the bottom end of your audio, particularly after cutting a little at 300Hz, you can add some warmth by boosting the bottom end. We rolled off the extreme low end earlier, but those frequencies are generally inaudible on most systems. To add audible bottom end, you need to boost in the 80 – 200Hz region. Where you boost depends on what (or who) you're EQing. The bottom end of male voices is usually around 100Hz; female voices are closer to 200Hz.

On a graphic EQ, you can find and push the frequency you're looking for. You may want to push the frequencies on either side slightly, as well. And the same goes for parametric; find the frequency, choose a fairly wide Q, and boost a bit. Preview your audio.

6. Finally, you need to decide if your audio needs any final sparkle. You can add this by boosting your high frequencies ever so slightly.

On a graphic EQ, start lifting at around 5KHz and boost the frequencies above 3dB. On a parametric EQ, select 5KHz for your shelving frequency and boost 3dB. Preview your audio. If you're happy with the sound, apply it! You may want to save this as a preset if this is a setting you think you'll be able to reuse.

Figures 1a and 1b show the results of all the preceding steps using graphic and parametric EQ. Your results may be slightly different; in fact, they should be, because you're listening to something different!




Figure 1: The results of the step-by-step example, illustrated on a) a graphic EQ and b) a parametric EQ.

Using a graphic and parametric equalizer

Using a graphic equalizer
Graphic equalizers divide the frequency spectrum into a specific number of bands and assign a fader to each band, as shown in Figure 1. The number of bands varies, depending on the hardware or software. The more bands you have, the narrower the range of frequencies you're affecting when you move a fader up or down.


Figure 1: A typical graphic equalizer (Sony Sound Forge)

Using a graphic equalizer couldn't be easier; you just grab a fader and push it up or down. If you're not sure exactly which frequency you want to work on, don't be afraid to experiment. Grab a fader, push it up, and preview the result. You should be able to hear that frequency being boosted in your file. If you can't hear it, push the fader up even more. Push it up until the frequency is horribly exaggerated. Don't worry; this is how audio engineers do it. Exaggerate to find the frequency, and then scale back the EQ until you've achieved the effect you're after.

This also works when you're looking for a frequency that you want to get rid of. If you can hear a nasty frequency, for example a noisy hiss or even a honking quality to a vocal, hunt for the frequency by boosting until you find the frequency that you're after. Sure, it will make your file sound even worse, but after you find the offensive frequency, you can cut it knowing you're cutting in the right place.

Remember that you want to boost wide and cut narrow. If you're boosting a particular frequency, you should also boost the frequencies on either side — about half the amount you're boosting the target frequency, so you get a nice EQ curve. If you're cutting, cut only the offensive frequency. Don't cut too much; it will make your audio sound hollow and unnatural. If you've ever seen an audio engineer use a graphic EQ, you'll see them adjust their settings to get a nice smooth looking curve, perhaps with one or two nasty frequencies cut.

Using a parametric equalizer
Parametric EQ is slightly different from graphic EQ, because you don't have faders for specific frequencies. Instead, you choose a frequency, how much around your target frequency you want to affect and how much you want to boost or cut. Parametric EQ is usually implemented using knobs, with a separate knob for the frequency, the Q (which is the term used for the width of the effect), and the amount of boost or cut. Some parametric EQ systems don't provide control of the Q; this is known as semi-parametric EQ.

Some parametric EQ also have a little switch that changes the EQ from standard parametric to shelving EQ. Shelving EQ affects all frequencies above or below the frequency setting. Shelving EQ that affects all frequencies below the target frequency is known as high pass, because all frequencies above the target frequency are passed through untouched. Similarly, shelving EQ that affects frequencies about the target frequency is called a low pass shelf, because all the low frequencies are passed.

Tip The EQ knobs on cheaper mixing desks are often fixed-frequency. They're also often shelving, so they're really not precision instruments. If you're going to use the EQ on your mixing desk, use it sparingly. After you've recorded EQ to "tape," it's hard to remove.


Figure 2 shows a software parametric EQ. You can see that it offers four fully parametric controls, along with both high and low pass EQ. Using a parametric EQ is very much like a graphic EQ, with the added ability to adjust the Q. To find the frequency you want, choose a very narrow Q and boost that frequency. Preview your audio, and move the frequency setting back and forth until you hit your target. Next, set your Q (remember: boost wide, cut narrow). Then adjust the boost or cut until your audio sounds the way you want it. If you want to work on another frequency, just use the same approach: Find, set your Q, and apply the right amount of boost or cut.


Figure 2: A software parametric equalizer (Sony Sound Forge)

EQ (Equalization)

EQ (Equalization)
Equalization, or EQ as it is commonly known, is adjusting the tonal quality of audio by turning up or down certain frequencies. Audio engineers use the terms boost for turning up and cut for turning down. Many of you are probably familiar with EQ via the bass and treble controls on your home or car stereos. In fact, you may have already fiddled with these knobs to adjust the sound; congratulations, you're an audio engineer. Using your ears as a guide, you adjusted the EQ until it sounded right to you. That's exactly what EQing is.

EQ is used for a number of reasons. Sometimes you may need to enhance the tone of your audio by boosting frequencies that make your audio sound more pleasant. You may need to boost these frequencies to make up for a deficiency in your mic or because your voice sounded different one day due to a cold or a late night. On the other hand, you may want to cut frequencies that aren't helping the sound of your audio. This can also be due to a deficiency in your signal chain or to get rid of something unpleasant, like an excessively nasal sound or too much bottom end.

How to use EQ
At the end of the day, it's all about making your audio sound better. You want your podcasts to sound bright and full, not dull and thin. You may notice that the terms used to describe the effects of EQ are very subjective. Audio engineers regularly use terms like "presence," "sparkle," "warmth," and "air." Believe it or not, these terms aren't that subjective; they're actually ways of referring to certain parts of the frequency spectrum — where exactly in the spectrum is subject to debate, but in the next section we provide you with a table of frequency ranges, along with common terms used to describe the frequencies in each range. The first thing to do, however, is to listen to your audio critically and ask yourself a few questions. The following questions start at the bottom of the frequency range, and work up from there, but you can think about them in any order you like:

- Is it "warm" enough? Is there enough low frequency information? Be careful here, because even good studio monitors have a hard time reproducing the lowest audible frequencies.

- What about the midrange? Are the voices clear and understandable? Or is the sound too harsh?

- How about the high frequencies? Does the audio sound dull? Or do you have the opposite problem — too much high frequency information?

If you're unsure about the answer to any of these questions, do what other audio engineers do — use something else as a reference. For example, you could listen to a radio program that is similar to yours, and do what we call an A/B comparison. Listen to the radio program for ten seconds, listening in particular to the low frequencies. Then flip back your podcast, and compare. Does yours have less? More? Flip back and listen to the middle frequencies, and compare. Finally, listen to the high frequencies. This should give you an indication of whether your podcast is up to scratch, and if it isn't, what you may need to add (or cut) to make your podcast sound better. The trick is to find the right frequencies.

What Signal Processing Is

When we talk about audio signal processing, we are manipulating level one way or another. For example, when we're equalizing (EQing) a file, we're manipulating the level of particular frequencies to change the tonal quality of the audio. When we use compression, we're turning entire sections of the audio signal up or down, depending on the input level. This may not make complete sense until you've heard these two techniques in action, but it's worth remembering that all we're doing is turning things up and down. It really is that simple. The tricky part is knowing what to turn up or down, and when.

One of the great things about working with audio is that we have such amazingly powerful tools. In the next few pages, you'll see just how malleable audio is. You can make things sound better in many ways and without making things sound unnatural. In fact, we're used to hearing processed audio; virtually all broadcast audio, be it radio or television, is fairly heavily processed.

This is why signal processing is important. We expect a certain level of quality from our audio, particularly in the post-CD world. Gone are the days when people walked around with transistor AM radios with cheap mono earpieces. We're used to high-quality, full-spectrum audio. If your podcast doesn't provide this kind of experience, it sends a none-too-subtle cue: amateur. Think about the difference between a big FM radio station sound and the local community college radio. Some of the difference is the type of programming and the on-air talent, but much of it is just plain inferior processing.

Don't let your podcast fall into that category. You absolutely should be producing a program that sounds at least as good as your local radio station. Anything less is just lazy, and your listeners will know it. Let's start with something we've all probably done unwittingly — equalization.

Archiving Your Masters

As you produce more and more podcasts, you'll notice your hard drive slowly filling up, particularly if you're saving numerous versions of your podcasts (which is highly recommended). At some point, you'll want to archive your files so you can clear out some space on your hard drive. A number of formats are available for your archives:

CD-ROM, DVD-R: CD-ROM or DVD discs are cheap and reliable. However, they are somewhat limited in capacity, and they start to take up lots of space on your shelves as your archives grow.

External Drives: External hard drives have much greater capacities than CD-ROM and DVD. They also have the advantage of speed, because you don't have to burn the disc. However, there is some question as to how long hard drives last — and if you try to prolong their life by not using them, some hard drives can freeze, taking all your data with them.

Tape-based Backup: Several tape-based archival formats are available. These are extremely reliable, but tape-based systems are expensive and often very slow.

As you can see, there is no perfect archival system. Each has its advantages and disadvantages. You'll probably want to start off burning your files to CD-ROM or DVD-R, and then move up to an external drive or tape-based system when the amount of files (and the success of your podcast) justifies it. Just be sure to archive everything, because you never know what uses you'll have for your programming. When the next media distribution mechanism appears, you'll be ready to take advantage of it.

Finally, it's worth mentioning that no archival storage method is immune to fires, floods, or theft. Consider storing copies of your masters in multiple locations. Storing a portable hard drive at work or in a storage space is simple enough. Online storage solutions also are available for that extra bit of security.

Tip Ironically enough, putting your hard drive in the freezer can "unfreeze" it. The theory is that the lowered temperature shrinks the components and the fluids in the sealed bearings inside the hard drive, thereby unlocking the frozen hard drive. This is intended as a last ditch solution, and if it works for you, get your data off as soon as possible and replace the drive. (Please note that the authors haven't tried this, and we can't be held responsible if something goes horribly wrong, okay?)

Editing (Podcast)

Chances are good that no matter how good you get at producing your podcast, you're still going to want to do some editing. You'll want to remove the countdown from the beginning of your recording, for one thing. And you may have plenty of other reasons to edit. Many podcasters do a quick "top and tail" edit, where they make sure the beginning and end of their podcast sounds right. This is the minimum you should do.

You can completely change the feel of a program by editing the flow of the material. You can make your guests sound better (or worse) with editing. As mentioned in the preceding section, you can also edit the program to include any pick-ups you did. Editing is a very powerful tool in your production arsenal. The following few sections are intended to give you an idea of how editing can be used to improve your podcast.

Editing for convenience
We covered the concept of pick-ups, where you record the intro and outro for the podcast after the actual interview, or perhaps re-record yourself asking questions to your guests, or even cover a topic that you forgot to cover in the body of the program. These pick-ups must be placed into the body of the podcast, where they belong. It's a simple copy-and-paste operation that saves you the hassle of having to do the entire show over again.

Editing for flow
Unless you (and your guests) have a significant amount of broadcast experience, chances are good that sections of your podcast may drag a little. Perhaps the answer to a question got a little longwinded, or it took you three or four attempts to frame a question the way you wanted to ask it. While a certain amount of this keeps the podcast sounding natural, too much of it can make your podcast sound unprofessional and frustrate your audience. If you find a natural place to edit, try taking out some of the extraneous material. For example, consider the following:

"I've been wondering, because you've been doing this for so many years, and, well, we've known each other for what, ten years now? Anyhow, as an observer of Internet trends and how they adapt, where do you see podcasting in five years' time?"

This could probably be cut to, "I've been wondering, where do you see podcasting in five years' time?" or even "Where do you see podcasting in five years' time?" Some of the removed content may have added color, but you really have to ask yourself whether the information is necessary, and whether your audience will be interested in it. In general, less is more, and it's best to edit when things start to wander off course.

Editing for content
Another thing to ask yourself is whether everything you recorded is necessary. You may have asked a few questions that really didn't go anywhere or didn't really yield any significant insights. Remember that your audience is tuning in for a reason, and if you're not staying on topic, you run the risk of losing them. Another thing to consider is how the topics covered in the podcast are related.

For example, you may start off talking about topic A and then realize that folks need to know about topic B to understand topic A. So you talk about topic B for awhile and then go back to topic A. You may consider moving the discussion of topic B before topic A. Of course, this depends on whether the edits are even possible and whether they feel natural. Editing is incredibly powerful, but it can be a double-edged sword. If an edit is noticeable, you're doing more damage than good. You can't always edit things the way you want.

Tip Another reason to do pick-ups is to cover edits. If you need to remove a large section of content, you can hide the edit by asking a question that seemingly joins the two edited sections.

Editing for quality
Most people, particularly if they don't have lots of broadcast experience, tend to insert lots of "ums" and "ahs" in their conversation, often without even realizing it. In fact, you may be surprised to discover your own verbal "tics" the first time you listen to your podcast recording. This is where editing can be incredibly effective, and it can make you and your guests sound much better. Edit out the offending tics, and presto, you'll sound like a professional.

Tip You may want to edit out breaths taken in the middle of sentences. Breath noise can be particularly problematic if you're using compression, because breaths sound louder. The simple solution is to remove the offending breaths. However, sometimes when you remove breath noise, the resulting sentence doesn't quite "flow" right. The solution is to add a small amount of silence where the breath was, so the sentence doesn't sound rushed.

Editing how-to's
Editing is a really simple operation on most audio editing platforms. All you really have to do is highlight the section you want to work on, and then either delete it or copy it so you can paste it somewhere else in your program. One thing that is really important, particularly if you're going to be doing extensive editing, is to save a "raw" version of the original interview. That way, if you somehow mess up the edited version, you always can go back to the original and start from scratch.

In fact, if you're going to be doing lots of editing, you may want to save intermediate versions. For example, the first thing you may do is tidy up the start and end, and remove all the ums and ahs to clean up the podcast. You should save this version, with something in the file name to indicate what stage of the edit you're at. After you've saved this version, you can then do further editing, removing or rearranging sections of your program. Save this as a third and final master of your program. If you decide that you don't like some of the edits, you won't have to start from scratch.

Recording (Podcast)

After you've got all your gear set up and you've practiced your microphone technique, you're ready to hit the record button and go, right? Wrong. Recording is not something you should rush into. In fact, the more time you take to test, prepare, and practice beforehand, the better your podcast will be. You've seen it in the movies or on television — the rock and roll roadie going from mic to mic saying, "Check-one-two," over and over again. There's a good reason for this. He's checking to make sure:

- The mic works

- The monitoring desk at the side of the stage is receiving signal

- The mixing desk out in front of the house is receiving signal

- A person standing in front of this microphone will hear himself

Luckily, you won't have to check quite as many things, but you really do need to make sure everything is working before you start recording. It's time for your own version of a sound check.

Sound check
Sound check is what you do before you press the record button. It's the last sanity check before you commit to your podcast. Even if you've used your recording setup a hundred times before, you should always do a quick sound check to make sure everything is working as expected. Your mental check list may differ depending on your situation, but essentially you have to check the following:

- All your microphones are working and have enough gain

- Any other audio sources are working and have enough gain

- All the equipment in your audio chain is functioning properly

- Your recording device is getting a good level

- Your aux send levels (such as the send to a telephone hybrid) are good

- The level in the headphones is good (if you're using headphones)

Of course, to test whether a mic is working, someone has to be talking into it. This is where "Check-one-two" comes in. Always set and check levels with the actual talent, so you get the levels right. After all, not everyone is as much of a blowhard as you are. In fact, some of your guests may be downright wallflowers. If so, a common trick to get your talent talking before the interview is to ask them what they had for breakfast. Even if they can't remember, or if they say they don't usually have breakfast, it's usually enough to get them started and serves as an icebreaker for the actual show. Of course, you can ask your talent about anything you like — just get them talking for a few seconds so you can check your levels. After you've checked all your levels and are satisfied that they look good, you're ready to start recording.

The countdown
You need to do two things to start your recording session. First, you have to press the record button. It's actually not unheard of for complete interviews to be done before people realize that they forgot to start recording. Unfortunately, one of your authors knows from experience. Save yourself the embarrassment, and make sure to press the record button.

Next, let the talent know that the recording has actually started, and leave a good spot for you to edit later on. This is where the countdown comes in. After you've pressed the record button, put a little identifier at the start of your file, including the name of your interviewee, and a quick countdown, something like, "Interview with Charles Peterson, talking about Leica cameras, in five… four… three… two… one." Take a deep breath. Introduce your show, your guest, the topic, and you're off and running.

The countdown is important for a couple of reasons. First, leaving a small, silent gap at the beginning of your podcast makes it much easier to edit. A common mistake novices make is to go from the sound check straight into the interview, without even so much as a breath in between. It may feel natural at the time, but you'll find when you're trying to edit to clean up the start of the podcast that it doesn't sound natural when you cut out the sound check chatter. Second, the countdown is a focusing mechanism, both for you as an interviewer and for the talent. It doesn't matter how off-the-cuff you want your podcast to sound; you still want it to sound professional, and giving yourself and your talent that extra few seconds to mentally prepare works wonders.

Tip A great way to test your talent's levels is to have them say their name and then spell it. This way you know how to pronounce their name, and how to spell it!

Intros and outros
Every radio and television interview program with a host has an intro and an outro. They're important, because they tell the audience what they can expect during the program, and they provide an overview of the topic. The intro to your podcast should have a "hook" in it, meaning a sneak peek or hint about the subject matter that makes the show irresistible to your audience. Not everyone in your audience is going to be riveted by every single guest and topic you decide to cover. We live in a busy world, and you've got lots of competition for your audience's time. Use the intro to tell your audience why you're excited about the program, particularly if you're covering a slightly obscure topic or you have a guest without marquee name recognition. If you do a good job of getting your audience excited, they'll stick around for the entire podcast.

Similarly, be sure to wrap up every program with a good outro. Obviously, you need to thank your guest(s) and your audience. You should also summarize the program, highlighting the subjects you covered. Then use this time to talk about your next podcast. If folks have made it this far, chances are good that they'll come back for your next podcast, perhaps even subscribe to your RSS feed. You can help ensure that they do so by letting them know what to expect next time around. This may be the first program that some listeners have tuned in to. Even if you don't know exactly who your guests will be or what topics will be discussed during the next program, you can at least give them an idea of what to expect.

Doing "drop-ins" and "pick-ups"
No matter how prepared you are, you may forget to cover something that you absolutely must have in your program. You may realize it at the end of your recording session when glancing at your notes, or heaven forbid you may realize it during the editing phase. Not to worry; if you were relatively careful setting up your levels, you should be able to do it as a "drop-in" or "pick-up."

A drop-in is when you record over an existing recorded piece and replace a section with a newly recorded version. For example, when movies are sanitized for viewing on airplanes and television, the actors have to drop-in over all the blue language and replace it with "drat!" or some other acceptable utterance. A pick-up is when you add to the end of the recording, knowing that you'll later edit the piece and insert the pick-up section where it belongs in the interview.

Drop-ins are more common in multi-track music recording, where an otherwise perfect performance may be marred by a single bad note. In cases like this, the musician or singer will sing along with the recorded version, and the engineer will "drop in" and record over the offending section. This requires quite a bit of skill and is not for the faint-hearted.

Pick-ups, however, will probably become part and parcel of your podcasting routine. For example, you may want to redo your introduction to reflect something that came up during the interview. Or you may want to rephrase some of the questions you asked, or perhaps even ask a question that you forgot earlier in the interview. In this case, you can simply do a pick-up, where you record what you need after the initial interview. Then, during the editing phase, you can move the sections around at will. Editing is covered in the next section.