Performing with professional-level accuracy on the trumpet can be quite a challenge for many. Often, difficulty with accuracy occurs for several reasons, the most common of which are:
1) Incorrectly hearing the pitch
2) Not playing in the center of the note
To overcome these challenges, I use a process I call “Sing. Buzz. Slur. Play.” It’s that simple. If there is a tried and true method, this would be it. This concept certainly didn't originate with me. I learned it from my teachers, and others use this method as well (see Phil Collins’ comments here).
Sing. Play each note on the piano and then sing it. This should be done very SLOWLY, even out of time at first. Be careful to pay attention to your attack when you sing. Do you crack the note when you sing (like you do on your trumpet)? Do hit the note under or over the pitch? Are you in tune when you sustain? If you crack the note and aren’t in tune, don’t move past the note, or interval, until you have it mastered. Do not let mistakes go by in this (or any) phase. Slow, diligent, and demanding practice helps to ensure that you’re consistently performing accurately. Allowing mistakes to persist during your practice is simply perfecting mistakes. In a way, you are telling yourself that the mistake is correct, when it isn’t.
Buzz. Still using the piano, follow the same formula. SLOWLY buzz each note. Be careful not to use too much pressure, and listen for fuzz in the sound. Try to buzz with a sound that is as pure and focused as possible. Again, listen for the accuracy of each attack, as well as proper intonation on each note and interval. Be sure that in this stage you tongue every note, even if it’s slurred in the music. This is essential because it forces you to play in the center of the note, thus assuring you will have accurate attacks. Repeat as many times as you need to be able to feel you have the pitches and intervals mastered. If you can attack each note in tune, your sound will expand and you will be able to play more efficiently on the trumpet.
Slur. Now move to the trumpet. In much the same fashion, you now will slur the pitches out of time. Whereas we tongue the notes on the mouthpiece, we slur when we return to the trumpet. This allows us to focus on sound quality, as well as playing centered pitches that are in tune. Your sound should be full and propelled by a healthy airflow. In this stage, we aren’t concerned about dynamic or articulation markings in the music. It’s slow, slurred, and sound-centric.
Play. Now begin to play correct articulations, dynamics, and rhythms as written. However, remain SLOW. Slow practice is always the essential key that unlocks success. You are able to hear each important detail: sound quality, intonation, and quality of attack. Faithful use of a metronome is essential because it will prevent you from speeding up too quickly. Be faithful to using your metronome.
This process isn’t just beneficial to challenging entrances and odd intervallic passages. It’s very helpful on extremely difficult technical passages (i.e. last two pages of the Jolivet Concertino or the opening of the Tomasi Concerto) . My rule of thumb is: the more challenging the passage, the more I need to sing it, buzz it, slur it, and play it.
This is a preferred way to help yourself perform with improved accuracy. It isn't necessarily fun or quick. It takes commitment and discipline. However, your sound will have more core, and you’ll find that in time you'll consistently be performing in the center of the pitches. It's worth doing it the hard way. 10 minutes of work using this pattern this will likely turn out to be more productive than weeks of mediocre repetition of the same passage.