Auditory Cues

Students often benefit from auditory warnings and auditory cues built into a daily routine.

Transitions 
Give a 2 to 5 minute warning prior to a change in the schedule- a timer, a bell, a special song
Give a signal when it is time to start an activity- clap your hands, ask students to repeat a phrase
Have a special auditory signal for the beginning or end of the school day
When traveling to different activities sing a song such as the Ants Go Marching

Learning Songs
Circle Time- a morning greeting song, a routine song or rhyme to start the day, sing the days of the week
Math and Reading- the alphabet song is an excellent example of an early reading song, there are numerous counting songs available, and even multiplication rhymes if you search for them!  School house rock is still around!
Social Studies and Science- throw in some key sounds in Science during experiments, find a song for the water cycle, etc.

Unstructured Times
Have calming music playing during nap or indoor play time
Have an auditory signal to indicate when the class is getting too noisy
Have an auditory signal when the whole class attention is needed

This is a great explanation of how to teach your students how to respond to an auditory signal.  Remember that just because you are using a signal at a certain time, doesn't mean that your students understand how to respond to it.  It involves direct instruction.