I think that's true Brian and other examples are available
Unless I have mistaken Dicks comment, he was referring to the function of Bert's 'grin' which was a technique to change the tone of the voice
Everybody has a built repertoire of tones but different environments emphasize some above others
Someone working in, say an office, will tend to use softer tones so as not to 'stand out in a crowd'
Steelworkers (MacColl's favourite example) need to belt everything out over the constant noise - that's the voice he takes home and to the pub (he described the Sunderland club venue, the noisiest pub he'd ever been in) all the singers tended to belt out their songs.
Controlling and extending tones was a feature of all Critics Group work
I found it very easy to strain my voice when I tried to sing songs requiring a hard tone because, as a domestic electrician, I used lighter tones 8 hours a day at work
I suspect that, had I continued to wok on the Docks, where I served my apprenticeship, my problem would have been reversed
These are extremes - we worked in subtleties in the C.G.
Sorry to bang on - it gets easier when you get to used to this way of work - and very easy - almost instinctive
Jim