Instruct: Classify an Amazon review as either positive or negative.
Query: Went From Operatic Baritone to Operatic Tenor at the Age of 70

I've sung professionally for the the last 40 years. I've performed opera, broadway musicals and pop. I've had the vocal leads in five original operas. Until I found out about Can You Sing a HIGH 'C' Without Straining? and Thomas Appell's vocal technique, I could not sing comfortably above an E above middle C. At 70 years old I purchased the book and began training with Thomas. I can now sing effortlessly to D above tenor high C with beautiful tone and quality. I was about ready to stop signing, but now my voice sounds better than at any time in my career. This technique has been the breakthrough I have been searching for my whole life.