David:

On my Twain's World CD-ROM there are 32 different references to the word "deaf" and nine more to the word "deef."  Most are paired with ... and dumb.

Highlights:

Following the Equator, VII, Ch XXV mentions Keller
"Women's Press Club" address mentions Keller
"Rogers and Railroads" mentions Keller

"A Little Note to M. Paul Bourget"--many references

The Innocents Abroad, Ch XV, mentions Abbe Scard the first teacher of the
deaf and dumb

in "1601" there is an instance of someone breaking wind so loudly it
threatens deafness (gosh, I love Twain)

Oh, don't forget in Huck (along with the usual quotes), that when he's on
Jackson's Island and the cannon goes off on the steamboat searching for
his body, Hucks says "it made me deaf with the noise. . ."  (looks like
textual foreshadowing to me)

Michael O'Conner