Singing helps to mimic the sound that should be heard when playing an instrument. It trains the ear to be attentive to various pitches and keys. If something sounds off you can immediately identify it. So, I truly enjoyed hearing such a melodic sound. Superb and yet breathtaking. Tres Bien
These warms ups in particular not popular in every band in the country but many. E flat and B Flat happen to be the most common and popular keys for an ensemble to play in. There is more to it but this is simply put.