Some years ago, I read an article in People Magazine called "Throat Doctor to the Country Stars". The specialist said the following, as I remember:

Country stars' voices suffer because the stars have not had training and their singing technique is hard on the voice.

Going on tour and singing too loud, too long can make the voice crash completely.

When the voice is sore, avoid caffeine, chocolate and alcohol, all of which are drying.
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I think this info was from some other source: talking is harder on the voice than singing. If your throat's sore, avoid talking as much as you can.

I hope Adele recovers.