I think the subject of using your voice could have been more than adequately covered in a volume half the size or even less. It's a bit long-winded and drawn out, but there are some useful techniques to be learnt from this book. More geared towards a theatre performer where voice projection is the key to being successful, but for me who wanted to learnt the art of voice-over and narrating, there was little here to be of any real help.
This was perhaps the first book I ever read on "voice" when I was starting out (I'm now a voice & presentation skills trainer). I've even written my own book on the subject for people who need to start even more basically than this book does.... and that's just about my only criticism... Ms Berry assumes a certain level of competence - not so much about "voice" but about, well, life the universe and everything.
Sometimes she can be a little hard to access unless you've got the right sort of background but it's really REALLY worth it when you make the effort.
The title encapsulates the clarity with which this book is concerned. Not only is it about what the voice is and does, but the importance of it to both physicality and personality. It may be read almost as a self-help book, with none of the frequent drawbacks of that genre, and is grounded in genuineness and clarity of purpose. as Berry says (p52): "We must rid ourselves of feelings of inadequacy, which usually come from false values anyway, and believe that it is enough to be ourselves...". Such a thorough introduction is given to the exercises, that the reader begins to look forward to their promised efficacy and power. Alas, however, I fell by the wayside in using them, so detailed, but rewarding are they. The book does come across as dated, naturally for a book first published in 1975, clearly pre-computer, and with contributions from the celebrites and politicians of that time - Richard Baker, Tariq Ali. It is also jarring that a book whose purpose is to promote clarity uses such poor grammar and sentence construction. There is too much redundant phraseology, such as "The next thing I want to say is this", "I will try to make this clear". That aside, the book is at once a practical manual, and an uplifting treatise on how to seek our individual humanity, what would in our times be called an holistic approach.