does any one know how long 16 bars is ?

@LucyRocks: so basically like 30-45 seconds? the piece had to be from the period of 1930's-1950's

30-45 second is a good guess, but you need to go by bars. Pick a song and search music notation for that song. Then you can count. Conversely, you can discern the time signature and count beats per bar- thus arriving at sixteen bars.

@LucyRocks: Frank Sinatra - When I'm Not Near the Girl I Love? im doing that one if you can help? it's an acapella