It is a well-known fact that feel-good music like Motown, reggae, and classical music played in animal shelters is calming for dogs and makes them less aggressive. As long as it is not heavy metal or hard rock, which causes an increase in anxiety.
Leaving music on during your absence will help calm a dog who suffers from separation anxiety. Cats, as with many things in life, seem to be indifferent to music. For the especially spoiled or even abused and nervous cats, there is specifically developed music created by researchers which are cat approved. These tunes soothe and alleviate anxiety.
These days there is music available which is specially produced for almost any animal, designed to reduce stress by a holistic method. It seems that chickens prefer classic music, Happy Egg Co. egg farmers and University of Bristol researchers found that the hens produce more eggs when they listen to classical music. Find out more here: soundcloud.com/happyeggs/sets/top-of-the-flocks-relaxing-tracks-to-set-feathers-a-flutter