TTS发音（IVTxtAuto）如何更换发音人（Mary，Mike，Sam，……）？

unit word1;interfaceuses
  Windows, Messages, SysUtils, Classes, Graphics, Controls, Forms, Dialogs,
  VTxtAuto_TLB, StdCtrls, ComCtrls, Mask, FileCtrl;type
  TForm1 = class(TForm)
    speedtext: TStaticText;
    speed: TTrackBar;
    Button1: TButton;
    Edit1: TEdit;
    Button2: TButton;
    gettext: TLabel;
    procedure FormCreate(Sender: TObject);
    procedure stopbtnClick(Sender: TObject);
    procedure speedChange(Sender: TObject);
    procedure prebtnClick(Sender: TObject);
    procedure nextbtnClick(Sender: TObject);
    procedure FormDestroy(Sender: TObject);
    procedure Button1Click(Sender: TObject);
    procedure Button2Click(Sender: TObject);
    procedure Edit1KeyPress(Sender: TObject; var Key: Char);  private
    { Private declarations }
  public
    { Public declarations }
  end;var
  Form1: TForm1;
  TTS:IVTxtAuto;
implementation{$R *.DFM}procedure TForm1.FormCreate(Sender: TObject);
begin
  TTS:=CoVtxtAuto_.Create;
  TTS.Register('superwords','superwords');
  speed.Position:=TTS.Get_Speed;
  speedtext.caption:='速度：'+inttostr(speed.position);
  speed.SelEnd:=speed.Position;
  //filelistbox1.Mask:= '所有文件(*.*)|*.*| 文本文件(*.txt)|*.txt';
end;procedure TForm1.stopbtnClick(Sender: TObject);
begin
  TTS.StopSpeaking;
end;
procedure TForm1.speedChange(Sender: TObject);
begin
  TTS.Set_Speed(speed.position);
  speedtext.caption:='速度：'+inttostr(speed.position);
  speed.SelEnd:=speed.Position;
end;procedure TForm1.prebtnClick(Sender: TObject);
begin
  TTS.AudioRewind;
end;procedure TForm1.nextbtnClick(Sender: TObject);
begin
  TTS.AudioFastForward;
end;procedure TForm1.FormDestroy(Sender: TObject);
begin
  TTS:=nil;
end;procedure TForm1.Button1Click(Sender: TObject);
begin
  close;
end;
procedure TForm1.Button2Click(Sender: TObject);
begin
  TTS.Speak(Edit1.text,vtxtst_READING);
end;procedure TForm1.Edit1KeyPress(Sender: TObject; var Key: Char);
begin
  if (length(trim(edit1.text))>0) and (key=chr(32))
  then  begin if  trim(edit1.text)=gettext.Caption
              then   begin
                     TTS.Speak(edit1.Text,vtxtst_COMMAND);
                     edit1.Clear;
                     end
              else   TTS.Speak('YOU ARE WRONG',vtxtst_STATEMENT);
        end;
end;
end.