The legato tonguing style is one of the hardest and most important things we learn on the trombone.
From the exquisite sounds of jazz ballads softly played by Tommy Dorsey or Bill Watrous, or a lush Jay Friedman performance of Tuba Mirum, the trombone is inherently an instrument capable of the most lyrical and sublime sounds. In the modern classical setting, legato has become even more important in many orchestras as trombonist increasingly apply legato beginnings of notes to even marcato figures. And beginning in the modern Jack Teagarden /Lawrence Brown) jazz trombone era, legato tonguing became and today remains *the* default mode of tonguing.
Unlike many other important skills on the trombone, the ability of a trombone performer in the legato style cannot be measured by tempo, or range. It is a purely aesthetic aspect of playing, and is inseparable from and integrated in the overall quality of sound of a player. Many, many trombonists can produce a full, pure and wonderful sound holding a note. Far fewer players can produce a full, pure, natural and seamless sound whilst changing notes.
I have heard the goal of how the legato trombone articulation should sound described as the seamless sound of a baritone or euphonium changing notes with the valve only. Certainly this describes a seamless articulation; however the legato trombone style can be so much, much more. In many musical situations this may be precisely what we want the articulation to sound like, but in others, perhaps a Lawrence Brown or Trummy Young wants a touch of slide into, around and out of the notes – these are subtle yet vital stylistic prerogatives of the performer which merely illustrate the importance of the art of the trombone legato in the musical palette.
The four keys to developing a beautiful legato style on the trombone are simply, the ear, the air, the tongue and the slide. The ear, because as with the development of most technical skills on the trombone, legato tonguing is best informed by listening to great performers and broadening and deepening the ear and mind