For singers in the tenor range (C3-C5).
100 Intervals: ascending and descending major and minor sevenths and octave.
How to practice:
The starting note will play twice before playing the first and second note of the interval. During this time, imagine the interval in your head and really hear it. Once the two notes have, prepare to sing both the start note and the interval. Do at least 5 minutes a day for good results.