Here's a cheerful thought, to discuss over the iced Christmas cake... According to audiologists Rothwell and Boyd of St Helier (Jersey) Hospital, amalgam dental fillings dull your hearing.
They tested healthy women aged 40-45 and found losses from 8 kHz upwards compared with other women who had non-amalgam dentistry. The strongest influence was at 14 kHz "where each additional amalgam filling was associated with a 2.4 dB decline".
Hi, Joe - I'm smiling right now! Well, at 2.4 dB per tooth, and 12 mercury-based fillings I shall need to set the EQ to... no, I would rather not go there!
Did these audiologists say that each amalgam caused an additional 2.4 dB decline @ 14 kHz? That would mean that, with your 12 fillings, you should have a 28.8 dB hole in the 14 kHz range! Of course, you might not even notice it if you did. Its pretty close to the top end of the human hearing range which is, in reality, around 18 kHz. But we are most sensitive to sounds in the 100 Hz to 4 kHz range. So, in short, I don't think anyone working as voice talent need worry about the effect of old fillings on their hearing unless they start losing frequencies closer to the middle of the normal audible range.
Yes! That's my reading of it. And indeed, I cannot now hear 14kHz at any level, though I could when young - 50 years ago. You can view the research abstract here: http://www.ncbi.nlm.nih.gov/pubmed/19085401 As to gold fillings, any precious metal I own is inside the mike :-/
Ah... the best thing a voice actor can do; put your money where your mouth is! ¦~$