Thanks for your replies, Ramon and Keith,
I will definitely keep your advice in mind. As to the humidity, at present, and for the past 30 years, I have lived within 3 blocks of the Pacific Ocean here in San Francisco, and the humidity has always been above 70% (I have two different humidity gauges), so I don't think that is the problem. I am a little hard of hearing, so I probably pluck the strings harder than most people, but I haven't experienced this problem with my classical guitar. Fortunately, I live two blocks from a well known luthier (Alan Perlman), and maybe I will have him take a look. Also, I would definitely prefer to use lower tension strings if possible, since in the past, my subjective impression has been that too high a tension tends to choke a guitar. Since the physics of a guitar is really complicated, I wonder if it is possible to get more projection and better coupling between the strings and top with lower tension strings. Are there any members of the forum out there that have some knowledge in this area?
Keith, I am aware that some buzzing goes with the territory, especially during strong compases, but the falsetas shouldn't be quite the same. And as I mentioned, when the strings were fresh, I noticed no problem, but after a week or so, only the basses started acting out. Kind of weird. In any case, thank you all very much for your replies.
P de V