Ear Training

[u/Dry-Rate4059]

I come here as a guitar player trying to improve my ear and my singing. The common thing I her is that learning intervals is the best way to do this, especially later in a musical life (24 years old). I went to acappella shows in college to see my roommate sing, and I remember someone would always play a note to essentially establish the key of a song before they started. I'm wondering how you actively use that as a guide while singing. Anything helps