The short answer is: No you cannot do that. This is not allowed.
Premiumbeat.com is a “Production Music” Library. Our music is available for licensing in Media Productions (website, video, DVDs, TV broadcast, film, games, etc.) as background music synchronized with your production. You cannot sing over the music track or add an instrument and market the results as if it was your music. We always own the Copyright of the music composition and recording. If you are producing a recording of your voice over the music to show your talent to producers that is fine – this is considered a “demo” usage and all you need is the standard license. But you cannot sell the recording.
If you are using the music to add your voice for an audio-book, story telling, hypnotherapy, guided meditation, self-help programs or any kind of narration this is completely allowed and you are welcome to use our music for that purpose. The difference is that the music is used as a background for a product that is not marketed as a “song” or a musical product. The purpose of the music is not altered in any way and the copyright of the music remains clearly and entirely in the hands of the music writer and the publisher. Please note that if you distribute or sell more than 1,000 copies of your media production you will need a Mass Duplication license.