Jussi Björling . . . ahh . . . his singing was out of sight.  You know, every instrument is, in a sense, an attempt by man to imitate the human voice in some way – and basically that’s the ultimate goal that everybody should have in mind when they play an instrument.  I think every instrumentalist can benefit greatly from listening to fine singers, especially opera or leider where they are telling a story.  And you can learn a lot listening to great pop singers like Frank Sinatra.  The guy really puts across the lyrics of a tune. – Adolph Herseth

It’s been said the trombone is the most vocal of all instruments. Listen to these singers. There are many; this is just a sampler. (Some of my biases may be apparent.)