Answer:

' Do repeatedly:
'   Ask the user for a note.
'   Play it for about a second.
'   (The user enters a note less than 37 to stop.)
'
PRINT "Enter the frequency (37-32000):"
INPUT FREQ
DO WHILE FREQ >= 37
  SOUND FREQ, 18
  PRINT "Enter the frequency (37-32000):"
  INPUT FREQ
LOOP
PRINT "Done!"
END