Whitney Houston's voice was almost destroyed by drugs.

Following years of heavy smoking and drug abuse, Whitney's singing was reportedly "unrecognisable" when she began recording her new album.

A source told Britain's Daily Mirror newspaper: "She was smoking a lot and taking a lot of drugs. Her voice was almost unrecognisable."

Houston ? once dubbed 'The Voice' for her five octave range ? was sent for singing lessons by industry executive Clive Davis and is now back to her high-note best.

The source added: "Thousands have been shelled out to train her back up to the original. But now she sounds terrific ? she is going to blow everybody away."

Houston's new, as yet untitled comeback album, is set for a November release.

In 2006, Tina Brown ? the sister of Whitney's now ex-husband Bobby Brown ? claimed Whitney was living in squalor, and hopelessly addicted to crack cocaine.

She released photographs to a US magazine showing the star's bathroom littered with drug paraphernalia, including a crack pipe.