Perfect pitch

[robert sadowski]

Dear list,
     I was tuning today for a Sunday concert and a musician came in and told
me that he wanted the two pianos in question to be tuned to A441.  He said
he just returned from a practice room and that piano was A439.  Now I'm a
firm believer in the human computer but is this possible?  I know he wasn't
carrying an RCT with him to know.  It's hard for me to believe anyone can
detect 1 cps difference by listening.  Am I in the dark about this?

Thanks,
Bob Sadowski RPT
Erie, PA.