[Music Playing]
Let us move up here and load another clip. Again, navigate to your media resources folder and find the file called Zoombasol tag. Let us listen to what does this sounds like.
[Demo]
Take a look at the waveform view for this clip. You can see that it is not at its maximum volume. There is a lot of head room between the top of the wave and the maximum allowable amplitude. This volume level is reflected in meters here at the top of the screen when they clip this play back. Take a look.
[Demo]
If you look at the meter more closely, you can see clearly that the colorful moving bar is the main attraction. But there are also some numbers that pop up in this region. They track the maximum amplitude so far as the clip is played out. You can tell exactly how loud the loudness point of your clip is by simply playing it and checking this number at the end. As we play it again, you will notice that the numbers are negative. As they reflect the values below the maximum amplitude, the maximum therefore is set it 0DB or decibels. And the amount of space that you have to work in there, is typically called the head room.
[Demo]
You could see there that our maximum amplitude was negative 9.68 DB for this particular clip. If a signal ever goes above 0 DB, it is called clipping. And it usually creates a horrible distorted sound that you never want to hear. If the signal is being clipped in SounDBooth, the clip indicator will light up red to alert you. This is the clip indicator right here, this thin little region. When you are editing your audio, it is usually a good idea to leave yourself some head room, which is to say you should not be operating within a hairs breadth of 0 DB at all times. Yes it is a good thing to have good healthy levels in your unedited recordings. But commonly in affect or edit will raise the overall volume of the clip, and you do not want clipping when you least expect it.
Also, if you are editing audio for a product which will be duplicated, you must be extremely careful not to exceed or even exactly match the available head room. Often, duplication houses will reject digital masters which reach 0 DB as they fear duplicating a badly clip source. Let us actually and go ahead and change some levels.
The most user controllable way to make volume changes in SounDBooth is to simply select the area you would like to change. Find the little floating panel with the blue numbers in up of the wave form view, and drag these numbers up and down with the mouse.
[Demo]
Notice that the wave form gives us a nice little preview of what the changes are going to look like. If I drag the numbers up, it expands the wave form to show how loud it is going to get. And if I drag the numbers down, it contracts the wave form inside of itself.
Let us turn it way up just as an example, and to perform the change, simply release the mouse button.
[Demo]
Let us hear what does this change sounds like.
[Demo]
Obviously, we made this section to clip much louder. And as you can see here, it appears that the signal actually goes above the available head room. This is confirmed by looking here at the clip indicator, which has indeed turned red. These numbers, which normally tell you how far below 0 DB, you are have actually changed over. I can clear out this clip indicator by simply clicking on it. But keep in mind this is not actually solved the problem of the audio going over 0 DB. It merely clears the clip indicator out so that next time something clips, it will be fresh and ready to warn me.
I am going to bring the volume here back down to a level which is a little bit more saying for our purposes. I had previously raised to 12 DB. So now, I am going to take it down 14 DB, which is going to be 2 decibels below its original volume. If your audio clips goes past 0 DB because of a change you have made in SounDBooth, the easiest way to get rid of that problem is to undo the change, and then to redo it again with less extreme values to avoid the clipping in the first place. If your audio has clipped or distorted in the recording process before you brought it in the SounDBooth, there is really not much you can do within the confines of SounDBooth to fix it, you will need to go in the previous portion of your production and fix the problem there. Note that when you are changing volumes, you can also drag this number down here in the control bar, the very same way that you can drag it up here.
This is a great technique for tweaking parts of the clip, or even for tweaking the whole clip by an arbitrary amount. But what if we want to evenly amplify a clip so that it takes up all of the available head room without clipping? This is a very simple process called normalization and it is easy. All you need to do is select the region you wish to normalize, or since we are going to normalize the entire clip, I will just deselect everything.
To apply simple normalization, simply click this louder button down here once. You can plainly see that the wave form has expanded to fill the available head room, and the spectral display has gotten much brighter. Let us take a listen to this clip now, and pay careful attention to what happens up here in the meters as the normalize clip plays.
[Demo]
Notice that SoundBooth normalize audio to -.3 DB and not to digital zero, to avoid any possible clipping problems both in duplication and if you are transferring clips to another digital audio editing application, this is all well and good. This is the most amount of volume that we can get out of this clip normally. But what if we need a little bit more? You know there is a fairly common problem that people have when producing commercials for television and radio or even when finishing a CD for a local band. Everything sounds great. But when you compare it side by side with big studio products, it is just not loud enough. Well it is time to meet hard limiting. Limiting is a pretty broad concept that will be discussed in a later lesson in more detail. However, as it applies here, it is quite simple. Hard limiting amplifies your signal, but not by a constant ratio.
When the amplitudes of the existing signal get very close to 0 DB, they are amplified less. There are many kinds of limiting. But in this case, hard comes from the fact that there is a hard and fast upper threshold for the volumes, which they will not exceed no matter what. The overall effect is one which the average volume is raised, but the peaks do not clip. To apply hard limiting, simply click the loudness button again. Each success of click in the loudness button amplifies the average volume by 3 DB. While it also makes the limiting effect more extreme. You can see our wave form grow with the first additional click, we will click one more time.
Let us take a listen to the limited clip, and again watch the meter closely.
[Demo]
You will notice that the highest volume the clip reaches is still -.3 DB, but the average volume of everything has been raised to a significant degree. That trade of hard limiting is that it decreases the dynamic range of your audio. It evens out the volumes. This can be a very good thing in small doses, but can have an adverse effect if taken too far. Using too much limiting can begin to make your audio sounds sanitized. And eventually will start introducing strange artifacts if taken to an extreme. I am going to come up here and load one more clip.
[Demo]
In your media resources, navigate to sound effects, and select the running stream. Let us take a listen to what this clip sounds like.
[Demo]
And it is essentially the same stuff throughout. The first thing I am going to do is trim this clip up a little bit. We certainly do not need 45 seconds of running stream. I will turn this empty little spot at the beginning as well.
[Demo]
You can see after the trimmings that were left with just over 11 seconds of audio. Take a look at the time line here at the top.
[Demo]
The beginning of this clip and the end for that matter sounds pretty harsh. It is like an instantaneous stream coming out here from nowhere, and it suddenly cuts out of the end as though we are never there. It wou
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