At some point I will recommend that students practice scales or a specific passage with "a drone." This means playing a constant, steady pitch via speakers or earphones, while playing the cello and simultaneously tuning each note to what you hear from the drone. When we check a D on the A string (played with 4th finger in 1st position) against the open D-string, we are essentially doing the same thing.
When you are practicing scales with a drone, the drone should be set to play the 1st note of the scale, also known as the "tonic." For D scale, play a D drone. As you play the notes moving up and down the scale, you'll hear that each note creates a harmony (or dissonance). As you adjust to be "in tune" with the drone, you'll hear these intervals become more or less resonant until you find that sweet spot where you are perfectly in tune with the drone and everything is clear and ringing.
If you are new to this kind of practicing, you'll notice that there are certain notes that stand out as VERY resonant or harmonious, while there are others that are quite dissonant.
The 1st note of the scale is the easiest to tune. As a perfect octave, it is most resonant. The 4th (subdominant) and 5th (dominant) notes are also very harmonious and resonant. The 3rd and 6th notes of the scale also create familiar harmonies that are fairly easy to tune against the drone. The 2nd and 7th notes of the scale are very dissonant but you can still tune them to a drone on the tonic of the scale.
I've created the video below to demonstrate how this actually works in practice.
When you practice with a drone, keep in mind these 3 things:
1. Do not use vibrato. It makes it difficult to tune because vibrato literally causes the sound to oscillate above (sharp) and below (flat) the center of the pitch.
2. Go slowly, play with long bows for each note so you have plenty of time to hear if you are in tune with the drone. You can add rhythm and pick up the tempo after learning how to make basic adjustments to the drone.
3. Be ready to make small adjustments with the left hand. Sometimes an imperceptible tilt of the hand is all you need to perfectly match the drone.
Please note, that I am playing OUT of tune ON PURPOSE so I can show you what it sounds like when you initially play a note that is a bit off and then gradually adjust to match the drone.
I like to use the album Drones for Tuning and Improvisation by Howie Smith.
Click here to find this album on iTunes.
Click here to find these drones on YouTube.