Stock photography site iStockphoto has announced that it will adding royalty-free audio tracks to its collection of downloadable stock content from September. iStockphoto claims that they will become the first company to offer stock imagery, video footage, vector illustrations, Flash files and audio for purchase under one payment model, on one site.

iStockphoto is looking for composers, performers, musicians and audio technicians to submit music, spoken word/voice, instrumental, ambient and sound-effect audio track submissions. Every time a submission is used, up to 40% of the revenue will go to the contributing artist.

iStockphoto current has over three million members. More details on audio submissions here.