From what I heard, Freddie disbanded since 1978 (more than it already was), andamong other things began to stay up late at night and sleep during the day.
While this does not explain the disaster in Japan, and also during the tour in that country,Freddie spent more Japanese to visit the country (it was his favorite)
Nor does it explain his bad voice quality during January 1979.
In simple accounts, the only logical explanation I find is that Freddie had a delicatethroat, and probably affected him quite abrupt changes in temperature and humidity,such as the climate of Britain, (wet and cold) climate is very different Germany, or the climate of France and Spain, and that could have affected more than usual in jazzperformance tour. (also adding that he had vocal nodules in 1979)
That can happen to anyone, for example I often sing, and had a voice in very poor condition in Arica, Chile (Zona desert, warm, dry and dusty), but now I'm on Valparaiso(More wet and cool) My voice recovered.
If you look good in concert, their best performances got them in England, Ireland andScotland. (Crazy tour, and Live Aid are very good examples)
The case of Japan is a good point if this is a country with a very changing climate, hashot and humid summers, and winters are very dry and cold, depending on the place is also usually affected by snow. Spring in particular has a very changing climate, with cool nights and very hot days.
Freddie may have been affected by this, and that would explain his voice unsteady, evenat times when his voice who was in better shape (February 1981).
Nevertheless, it seems that the case of 1979, is a very timely event, to hear therecordings, Freddie sounded fairly well for the jazz standard tour until April 22, 1979,after that, his voice deteriorated too much, and then again to acquire the jazz standardtour during the first days of May.
I guess that week must have had a cold, as it showed in his interviews that Tocia all the time, or who had difficulty speaking, on the other hand a week is just the period in which a person is slow to recover from a cold .
My point is the case in Japan during 1979, could not have been vocal nodules, since these take a long time to heal, and the improvement that has Freddie from May 1 through May 5, is pretty incredible too much to be just a matter of vocal nodules.