The sound names refer to the letters: C, D, E, F, G, A, and B. Their pitches are fixed. Its foreign name is pitch names. The white keys and black keys on the piano keyboard are arranged according to fixed rules, and the fixed height of the note on each key is the note name. Countries use different phonetic names due to differences in pronunciation, writing and historical origins.

Roll-call is a musical term. The name used to facilitate the singing of the melody is called roll-call. Currently, we use the seven basic tone levels in the natural major mode to be sung as do, re, mi, fa, sol, la, si (or ti). The various musical notations are just expressed in different forms. A sound will have different notes in different music scores, and it can be sung into different "roll calls" by different people according to their habits, but the sound you want to sing can only be this one.

Extended information:

The German sound name system uses seven sound names: "C, D, E, F, G, A, H", with H to represent the B sound in the British and American systems, and use "B" to represent the bB sound in the British and American systems.

In the musical sound system, there are only these seven note names, and the names of other note levels are just recycled or varied uses of these seven note names, which can be clearly seen on the piano keyboard. The notes on the keys are the basic pitch levels.

When singing a music score, the seven roll calls are usually sung at the musical level, namely: do, re, mi, fa, sol, la, si. However, when using the staff, the key signature of the music score must be taken into consideration, and the solfa method must be used. There are two commonly used solfa methods: first-key solfa and fixed-key solfa.

Reference materials:

Baidu Encyclopedia - Sound Name

Baidu Baidu - Roll Call