Summer is a perfect time for getting out of old routines and devoting time to music. New England holds some special retreats that offer programs where choral singers can get away for a week or more to focus and learn; elsewhere, singers take advantage of summer freedom to rehearse and perform a special choral work. Many choruses open their doors to the public to host “summer sings,” where participants sing a masterwork in a single session under expert direction, and often with professional soloists— a perfect way to participate in great music with a minimum commitment.