The importance of monitoring in the recording studio
Although monitoring is vital in many aspects of audio, here we'll look at monitoring for music recording.
In the earliest days of recording, there was no such thing as monitoring as we understand it today. Music was recorded by purely acoustic means directly onto disc. The recording could only be heard after it had been made. Test recordings could be made and the position of the musicians relative to the recording horn modified as necessary, but there was no such thing as monitoring during recording.
The change came with electrical recording. At some point, someone must have realized that the electrical signal from the microphone could be tapped off and used to drive a loudspeaker. Positioned in a separate room, this could be used to monitor the recording process. The positions of the musicians relative to the microphone could be judged and adjusted before the recording actually started. And as the recording took place, the performance could be monitored to make sure there were no errors in playing.
So monitoring developed from not even existing at all, to 'eavesdropping' on the musicians as they played, to what is now one of the most important parts of the recording process. It is absolutely essential to understand the importance of monitoring in music recording. Monitoring has two main functions. One is to allow the producer and the recording engineer to judge the musical and technical aspects of the process. The other is to judge how the eventual listener will experience the recording. Let's look in more detail...
Monitoring the recording
In any music recording there will be a producer and an engineer. These days, one person might carry out both roles, but it is useful to consider them separately.
The producer will judge the musical aspects of performance, and also the technical aspects of the playing. Is the performer putting the right amount of emotion into the song for example? Did the pianist play a wrong note? Are the keys on the flute clicking?
Meanwhile the engineer will be trying to get a good quality of sound by optimizing the microphone selection and positioning. At the same time he or she will be listening out for any problems. Is there noise or buzz? Is the microphone overloading? Is there any low-frequency rumble from the air conditioning system?
The purpose of monitoring here is for the producer and engineer to know precisely and in detail what is contained in the signal being recorded. To do this the monitoring system, consisting of power amplifiers and loudspeakers, must reveal everything about the recording, to a degree of detail that very few listeners could experience. Anything that isn't heard in the studio might well be heard by a listener with an expensive hi-fi system, and clearly that is something that should never happen. The professionals must be able to hear detail in a recording to a higher standard than consumers ever can.
For this purpose, 'main monitors' are used. In a well-specified recording studio, these will be large and expensive loudspeakers, costing upwards of $10,000. The acoustics of the control room will be designed around these monitors in order that they can be heard at their absolute best.
The standard configuration for monitor loudspeakers, whatever the size, is an equilateral triangle with the loudspeakers at two corners, the engineer at the other. The loudspeakers should point directly at the engineer.
Judging what the listener will hear
This is just as important as precise monitoring of the recording. The main monitors will tell the producer and engineer what is contained in the signal being recorded. But it won't tell them what the eventual listener will hear. Few listeners have hi-fi systems anywhere near as good as studio main monitors, although undoubtedly a small minority does.
It has been normal since the 1960s for a studio to have a pair of monitors that are typical of what an ordinary listener would have. The classic example is the Yamaha NS10, which become practically the standard for this kind of monitoring in the 1980s. Since then, many similar small monitors have become available.
It is important that these loudspeakers should not sound particularly good in themselves. They must not flatter the recording, otherwise the recording will sound dull on less flattering loudspeakers. In fact they should sound rather plain, so you have to work hard on the mix to get a good sound.
The small loudspeakers described above are often called 'nearfield monitors'. This is because traditionally they are positioned quite close to the engineer's ears. This has the effect of excluding the acoustics of the control room to a significant extent, because the direct sound from the loudspeakers is much stronger. This is good, because it is possible to work with the same monitors in different studios and hear very nearly the same sound. The drawback however is that hardly any listeners would have their loudspeakers as close. But it is a workable technique and its popularity over such a long time demonstrates its worth.
The variety of listening environments
Whereas in the 1990s and earlier, mixes tended to be optimized for small hi-fi systems, most listening these days is done on headphones, earbuds, or in the car. It is important therefore that a mix should sound as good as possible on whatever system it is played - earbuds, in-car, computer loudspeakers, hi-fi, and of course radio and television.