eSpeakNG is a compact open source software speech synthesizer for Linux, Windows and other platforms. It uses a formant synthesis method, providing many languages in a small size. Much of the programming for eSpeakNG's language support is done using rule files with feedback from native speakers. Wikipedia
root@edison:~# opkg install espeakroot@edison:~# espeak --voices=variant
Pty Language Age/Gender VoiceName File Other Languages
5 variant F female2 !v/f2
5 variant F female3 !v/f3
5 variant F female4 !v/f4
5 variant F female5 !v/f5
5 variant F female_whisper !v/whisperf
5 variant - klatt !v/klatt
5 variant - klatt2 !v/klatt2
5 variant - klatt3 !v/klatt3
5 variant - klatt4 !v/klatt4
5 variant M male2 !v/m2
5 variant M male3 !v/m3
5 variant M male4 !v/m4
5 variant M male5 !v/m5
5 variant M male6 !v/m6
5 variant M male7 !v/m7
5 variant M whisper !v/whisper
5 variant 70F female1 !v/f1
5 variant 70M croak !v/croak
5 variant 70M male1 !v/m1
root@edison:~# root@edison:~# echo "hello world" | espeak -ven+whisper
ALSA lib /export/users/neck/iotdk_3.5_dev/workdir/build_edison/tmp/work/core2-32-poky-linux/alsa-lib/1.0.28-r0/alsa-lib-1r
root@edison:~# root@edison:~# echo "hello world" | espeak -ven+m5
ALSA lib /export/users/neck/iotdk_3.5_dev/workdir/build_edison/tmp/work/core2-32-poky-linux/alsa-lib/1.0.28-r0/alsa-lib-1r
root@edison:~# root@edison:~# espeak --voices
Pty Language Age/Gender VoiceName File Other Languages
5 af M afrikaans other/af
5 an M aragonese europe/an
5 bg - bulgarian europe/bg
5 bs M bosnian europe/bs
5 ca M catalan europe/ca
5 cs M czech europe/cs
5 cy M welsh europe/cy
5 da M danish europe/da
5 de M german de
5 el M greek europe/el
5 en M default default
2 en-gb M english en (en-uk 2)(en 2)
5 en-sc M en-scottish other/en-sc (en 4)
5 en-uk-north M english-north other/en-n (en-uk 3)(en 5)
5 en-uk-rp M english_rp other/en-rp (en-uk 4)(en 5)
5 en-uk-wmids M english_wmids other/en-wm (en-uk 9)(en 9)
2 en-us M english-us en-us (en-r 5)(en 3)
5 en-wi M en-westindies other/en-wi (en-uk 4)(en 10)
5 eo M esperanto other/eo
5 es M spanish europe/es
5 es-la M spanish-latin-am es-la (es-mx 6)(es 6)
5 et - estonian europe/et
5 fa - persian asia/fa
5 fa-pin - persian-pinglish asia/fa-pin
5 fi M finnish europe/fi
5 fr-be M french-Belgium europe/fr-be (fr 8)
5 fr-fr M french fr (fr 5)
5 ga - irish-gaeilge europe/ga
5 grc M greek-ancient other/grc
5 hi M hindi asia/hi
5 hr M croatian europe/hr (hbs 5)
5 hu M hungarian europe/hu
5 hy M armenian asia/hy
5 hy-west M armenian-west asia/hy-west (hy 8)
5 id M indonesian asia/id
5 is M icelandic europe/is
5 it M italian europe/it
5 jbo - lojban other/jbo
5 ka - georgian asia/ka
5 kn - kannada asia/kn
5 ku M kurdish asia/ku
5 la M latin other/la
5 lfn M lingua_franca_nova other/lfn
5 lt M lithuanian europe/lt
5 lv M latvian europe/lv
5 mk M macedonian europe/mk
5 ml M malayalam asia/ml
5 ms M malay asia/ms
5 ne M nepali asia/ne
5 nl M dutch europe/nl
5 no M norwegian europe/no (nb 5)
5 pa - punjabi asia/pa
5 pl M polish europe/pl
5 pt-br M brazil pt (pt 5)
5 pt-pt M portugal europe/pt-pt (pt 6)
5 ro M romanian europe/ro
5 ru M russian europe/ru
5 sk M slovak europe/sk
5 sq M albanian europe/sq
5 sr M serbian europe/sr
5 sv M swedish europe/sv
5 sw M swahili-test other/sw
5 ta M tamil asia/ta
5 tr M turkish asia/tr
5 vi M vietnam asia/vi
5 vi-hue M vietnam_hue asia/vi-hue
5 vi-sgn M vietnam_sgn asia/vi-sgn
5 zh M Mandarin asia/zh
5 zh-yue M cantonese asia/zh-yue (yue 5)(zhy 5)
root@edison:~# root@edison:~# echo "hola mundo" | espeak -ves-la
ALSA lib /export/users/neck/iotdk_3.5_dev/workdir/build_edison/tmp/work/core2-32-poky-linux/alsa-lib/1.0.28-r0/alsa-lib-1r
root@edison:~#