Here is a link to a California High Speed Train (HST) fact sheet, dated 2010, and signed by the CEO and Chief Engineer of CHSR. It's the first thing that came up when I did a Google search. It doesn't look like they are trying to keep anything hidden from the public.
It addresses these questions:
• What sound is produced by HST?
• Who could be affected by the sound of HST?
• How is the sound of HST described?
• What physical elements of the environment and operational factors affect the sound of
the high-speed train?
• What are the estimated sound levels of a HST System?
• How is the audible impact from HST operations determined?
• What can be done to mitigate HST noise?
• What are some of the benefits of HST operations along existing rail corridors?
Opens PDF doc:
http://www.hsr.ca.gov/docs/programs/eir_memos/Proj_Guidelines_SoundFactSht.pdf