Long tones are exactly what the name suggests them to be. They are tones that are sustained for a long period of time. As I mentioned, they are often overlooked in instrumental studies. This occurs because most students desire to obtain speed in their playing. The reason we all strive to learn how to play an instrument (or sing) is to impress others. Performing passages with fast, flashy and elaborate notes always seem to be the best way to impress others. Long tones seem easy to achieve and boring to perform. However, long tones that are executed correctly are both challenging and constructive tools for increasing one's performance level.
Tone quality is just as important of a performance quality as flash and speed. Without a desirable tone the fastest notes in the world will still be perceived as annoying instead of being entertaining. Developing your tone as a performer should be accomplished in two stages. First, one should look to develop a tone that is consistent, neutral and controlled. This will allow for the performer to achieve changes in pitch, rhythm, dynamic, and articulation while maintaining a consistent tone. Developing a consistent tone quality with long tones is the first step in this process. Then a performer can gradually increase the fluctuation of musical elements within his/her playing while striving to maintain a consistent tone.
Consistent long tones also help to improve intonation on instruments where intonation can fluctuate due to performance technique. Many performers practice long tones in front of an electronic tuning device to have a visual display of their intonation. Repeated practice in this manor causes the performer to remember what it feels like to play in tune. Eventually this type of tone production become second nature.
The second stage of tone production is developing one's own unique sound. Each performer's tone is unique, since it is shaped by specific details of his/her playing style. The unique quality of a performer's tone is even more relevant with instruments which require breath, because the tone is shaped by both the instrument and the performer's body. Finding and perfecting your unique tone is a performance quality that will distinguish you from other performers. Being identifiable and unique is often a beneficial quality in musical performance.
One of the best ways to develop your unique and identifiable tone is through the use of long tones. After a musician has developed a consistent and controlled tone, he/she can begin to listen to an examine the unique qualities of that tone. While holding out long tones, desirable tone qualities can be accentuated through experimentation. The result will be a signature tone that is unique to the performer.
I hope that this discussion has helped you to recognize the importance of long tones in the study of musical performance. A well rounded musician develops every aspect of their performance ability, including tone quality. I still incorporate long tones into my practice routine regularly. The results of long tone studies are noticeable and valuable.