If those sounds don’t need to be loud it is not a big problem; you just need to set the volume where you’d like it to be and you’re done.
The first thing that you’ll want to do if the sound is not loud enough is to normalize it. Normalizing is a process in which the computer searches and finds the highest volume point. Let’s say you recorded a door and the highest point in the sound was -7dB. The computer will take the sound and increase all of it by 7dB. This way the sound is exactly the same, only louder and the highest peak in the sound will be the highest possible digital sound level (for 16 bit sound that will be 1111111111111111). Every sound software packages that I know of has a normalizing function. You will usually find it under the Effects menu.
If after normalizing the sound is still not loud enough (which will happen a lot), there are mainly two things sound effects editors are doing to address the issue:
1) Add more sounds, which we call “layering” (2) Use compressors
Let’s start with layering. First of all, if you layer just to get more loudness, that’s not a good idea. You should only do that if it’s also adding to the richness and the character of the sound. For example, if you cut the sound for a building crashing down, it is very unlikely that you can find the perfect single sound in the library that will cover the crash.(The way we do it is to start layering sounds like huge impacts, explosions, stones crashing, glass breaking, stones debris, metal creaking, metal debris, etc.
Let’s see how layering making things sound louder…((When you have one normalized sound and, at the same time, you add another normalized sound, what you get is a mix of those two sounds, but also twice the energy (it’s like adding 3 dB of gain). If you had those two sounds, each on its own channel, and send it to the mix stage it will play louder but will also make the view meters on the stage jump 3 dB higher.((So now what happens is that you moved the problem to the mixer. This is not necessarily a bad decision. Mixers are very good at dealing with this problem. However, this is adding work for them, especially when two sounds are still not enough and you ended up adding three, four or even more sounds. It is not just the loudness issue that the mixer need to take care of — it is also having to put all those channels at the same volume with the same effects and EQ (or to his liking, which is not always the way you like it mixed). So the way I see it is if the production budget is not huge, you better do this work yourself. And, when you send a door slam to the stage, it better be one sound. ((Of course it can be 3 sounds that you mix yourself and bounce to one channel.)
If you’re asking, “Why not send one week sound and let the mixer deal with the loudness issue on the stage?”, my answer is:(There are almost always clients on the stage when a show is mixed. And, they will probably jump off their chairs when something they want to sound huge sounds smalls and puny the first time they hear it. For me, it’s also the fact that if you can’t hear the sounds at the right level when you’re editing you’ll not be able to tell if those sounds will actually work well in the mix. home theater