Enable "Personal Voice" in a terminal to use 'say' with your own voice

personal-voice.c

/*
  Compile via:
  gcc -x objective-c -framework AVFoundation -framework Foundation personal-voice.c -o personal-voice
  Run it in a terminal (make sure you authorized apps to use your personal voice)
*/

#import <AVFoundation/AVFoundation.h>

int main(){
  [AVSpeechSynthesizer requestPersonalVoiceAuthorizationWithCompletionHandler:^(AVSpeechSynthesisPersonalVoiceAuthorizationStatus status){
     // authorization popup should be visible now
  }];
  [[NSRunLoop currentRunLoop] run];
  return 0;
}