The following are audio courses, they are different from each other, some you may like others not so much, but it will depend on your level and previous understanding of grammar. Berlitz Spanish Audio Course, Instant Immersion, Learn Spanish in your Car, Spanish In-flight, Mitchel Thomas Spanish Programme, Pimsleur Spanish Course, Teach Yourself Spanish (this is a course with a book, but the audio can be used independently from the book). I hope this helps you.