The gnome-speech parameter ranges set up for espeak do not match espeaks docs or capabilities.  In particular:

The pitch should range from 0 to 100
The rate should range from 80 to 369
The volume should range from 0 to 100
The capitals should range from 0 to 3

Here's the relevant snippets from the eSpeak code:

Pitch (see this line in http://espeak.sourcearchive.com/documentation/1.39/src_2speak__lib_8h-source.html):
00388       espeakPITCH:   base pitch, range 0-100.  50=normal

Rate (see these lines in http://espeak.sourcearchive.com/documentation/1.39/setlengths_8cpp-source.html):
00121       if(wpm > 369) wpm = 369;
00122       if(wpm < 80) wpm = 80;

Volume (see this line in http://espeak.sourcearchive.com/documentation/1.39/src_2speak__lib_8h-source.html):
00390       espeakRANGE:   pitch range, range 0-100. 0-monotone, 50=normal

Capitals (see these lines in http://espeak.sourcearchive.com/documentation/1.39/src_2speak__lib_8h-source.html):
00396       espeakCAPITALS: announce capital letters by:
00397          0=none,
00398          1=sound icon,
00399          2=spelling,
00400          3 or higher, by raising pitch.  This values gives the amount in Hz by which the pitch
00401             of a word raised to indicate it has a capital letter.