Most professionally released music actually has a fairly standardized set of standards for how the sound is to come out. This developed from the standardized methods with which most music was released, such as home distribution methods and radio. Because of this, there tends to be different levels that are respected for the music. What this is in practical terms is a general range of loudness that the sound can be in, though it can peak above this and drop below it at times. Here is a look at how these levels work when it comes to professional music.
How the Sound Levels Work
The general loudness of a sound is measured in decibels. In reality, a decibel is a measurement of the sound pressure level. A measurement of 0 dB is the absolute lack of sound, which indicates nothing living and no sort of autonomous machine. at around 130 dB the ears begin to hurt, so you see how these levels work.
The range of acceptability for professional audio levels for music recording are much lower than that, as are those used with film and television audio. The reason for this is that the instruments that record and broadcast the sounds can distort the sound if it goes beyond a certain level. The importance for recording audio is to get it accurately and cleanly without any distortion, so the levels are brought down to an acceptable place with the knowledge that the listener has the freedom to amplify it if desired. When working in a sound mixing program, such as Pro Tools, you will find that you can finally create a flow where sounds come in and out at slightly different levels for the final export.
In general, most recordings want to stay in between -12 dB and -6 dB, with an absolute peak at -3 dB. There can often be a limiter placed on the clips so that it will cap out the clipping that may happen from going into a distortion level. You can set this according to what you want, but you usually have the ability to adjust your levels according to the loudness of the instruments and performer you are working with so that you are recording in a way where clarity comes in perfectly during the audio production and mixing.
It is important in the final mix to make sure that there is not a flat SPL among all sound components. For example, there are times that the singer should be much louder and other times that the guitar should dominate. This does not always need to happen when the sound is being recorded and professional audio levels for music recording are much more about getting clarity than making it sound as though it will when it will be finally ready for audiences. This process happens during audio mastering, where you decide what comes forward and when.
When you are actually working on this you do not always need to keep an eye on the numerical specifics of the professional audio levels for your music recording, but instead just monitor the lights that will accompany the level measurement system. This means that you will want to see that things stay in the green most of the time, while occasional peaks can go into the yellow. Red will include clipping, and may cause distortion or initiate the limiter if it is on. You can increase or decrease the gain according to what your reading are during test runs of the recording.
Source: Author's own experience.