Although Mr Major has in the past gone on the record stating that he personally would resist the blandishments of the image consultants, a scientific analysis organised by the Independent on Sunday has demonstrated beyond doubt a surprising transformation in the Major tones.
They are now more than a 10th of an octave lower than when he first became leader of the Tory party, and his speech today is more colourful, and less monotonous, than it was when he moved into Number 10.
Both effects are consistent with voice coaching. A spokeswoman at 10 Downing Street dismissed the possibility that Mr Major's voice had changed as a result of coaching or speech therapy. "Mr Major has not had any voice training and I'm afraid I can offer no other possible explanations if what you say is true," she said, "although I suspect that any two samples of any individual's voice would register a difference."
Our analysis, however, suggests otherwise. To discover just how much John Major's "new" voice has changed we took two studio recordings of him being interviewed to two of the country's leading authorities on phonetics - Professor John Wells, of University College London, and Professor Peter Roach, of the University of Reading. The first sample tape was recorded in 1992, and the second was an interview with John Humphrys on BBC Radio 4's Today programme 10 days ago. They revealed a significant change.
Professor Wells ran the tapes through a Laryngograph computer which takes thousands of measurements of the recorded material to produce a series of graphs that plot the overall pitch and range of Mr Major's voice.
"The results from the computer confirmed statistically what I had detected when I first listened to the tapes," he said. "Mr Major's speaking voice is now at a lower register. The Laryngograph shows that it is in fact just over seven Herz lower. The most recent tape also reveals that he is using a wider range of pitches, which means his voice now carries more shades of emphasis and is less monotonous."
Professor Roach examined the tapes in Reading University's Speech Research Laboratory. "You can tell there has been a change," he said. "Mr Major has a naturally high-larynx voice, that is to say, his larynx is set unusually high in his throat. It sounds to me as if he has been learning to lower his larynx. This has the effect of reducing the metallic quality of his voice, and the lower pitch sounds less tense and is generally aesthetically accepted to be more pleasant on the ear. I would not expect a change like that to be a normal part of the ageing process."
Despite the shift towards a deeper, more authorative delivery, Mr Major's accent and pronunciation remain the same.
According to the experts, as well as a high larynx Mr Major has a constricted pharynx, which accounts for his slightly strangulated vowel sounds . "Voice coaching can help relax the soft tissue in the larynx which in turn helps to lower the pitch," said Professor Roach.
In the average mature male the voice is in the range of 90 to 130Hz and in 1992 Mr Major's voice was at the top of the scale; today his voice averages 123.5Hz.
"Lowering the larynx is not something an individual normally does alone. I would imagine someone has advised him, and this is further supported in my mind by the fact that the voice is now more expressive, which is one of the ways people are taught to make their voices more interesting," said Professor Wells.
In speech analysis, a person's pitch is the most salient indicator; it is the first speech skill we acquire and becomes in effect the skeleton upon which the other aspects of the individual's voice are overlaid. It is extremely rare for the pitch of a mature adult's voice to change in the normal course of events.
The pitch can be changed by speech therapists who sometimes use the same Laryngography equipment to work with patients. It works by attaching a pair of electrode sensors to the throat of the patient, and asking them to repeat sounds into a microphone linked to a computer.
Each sound makes a plot on the screen in front of the patient and they can see that by following certain exercises, they can learn to relax their larynx and thus shift the pitch of their speaking voice down the register. If this is done for long enough a new habit is formed, and the pattern of speech can be altered for good.
Yesterday, Terry Major-Ball expressed surprised at the news of his brother's "new" voice. "You genuinely amaze me. I must say in all honesty I have not noticed any change in his voice at all, but neither have I been looking for one," he said at his home near Croydon. "I tape all my brother's speeches so I am not wrong-footed when approached by the media, and I must say he sounds the same now as he ever did. He has never mentioned the topic of voice coaching to me, and I can only think a person's voice changes in step with the more public speaking one is required to do."Reuse content