There are Channel ARI Demos in which we can control channel state: ring, answer, play silence, play some tone or audio-file (https://github.com/asterisk/ari-examples/tree/master/channel-state, https://wiki.asterisk.org/wiki/display/AST/ARI+and+Channels%3A+Manipulating+Channel+State) Is it possible to receive some chunks (parts, buffers, etc.) of call voice (which are created by remote subscriber) or write chunks of voice, for example like a some array of bytes (not from file) in some audio format (alaw, ulow, etc.).
You can use asterisk EAGI interface to get voice data.
Other option is use Record or Mixmonitor app for record channel(channel have be put to Stasis to allow dialplan control by ARI)
"Write chunks of voice" can be done by application Playback
Also you can create your own application using c/c++, compile it into asterisk and get result you want.
No, you can't redirect voice directly using ARI.