public virtual ISpeechObjectTokens GetVoices(string RequiredAttributes, string OptionalAttributes);

该函数返回一个ISpeechObjectToken集合ISpeechObjectTokens，ISpeechObjectToken描述了每个朗读语音
函数两个参数均为对所得到集合的限制，第二参数为对第一参数的补充，比如使用

GetVoices('Gender = male', '')

就会得到男声集合
对于这些参数，一般有如下参数：Name,Vendor,Age,Gender,Language[有没有更多的不知道，翻过SAPI的帮助也没找到相关说明]
调用以下语句作以说明

            ISpeechObjectToken sot = svc.GetVoices(String.Empty, String.Empty).Item(0);
            System.Diagnostics.Trace.WriteLine(sot.GetAttribute("Name"));
            System.Diagnostics.Trace.WriteLine(sot.GetAttribute("Vendor"));
            System.Diagnostics.Trace.WriteLine(sot.GetAttribute("Age"));
            System.Diagnostics.Trace.WriteLine(sot.GetAttribute("Gender"));
            System.Diagnostics.Trace.WriteLine(sot.GetAttribute("Language"));

输出中会显示

Microsoft Mary
Microsoft
Adult
Female
409;9

        SpVoiceClass svc = new SpVoiceClass();
        private void button1_Click(object sender, EventArgs e)
        {            
            svc.Volume = trackBarVolume.Value;
            svc.Rate = trackBarRate.Value;
            svc.Voice = svc.GetVoices(string.Empty, string.Empty).Item(comboBoxLanguage.SelectedIndex);
            svc.Speak(textBox1.Text, SpeechVoiceSpeakFlags.SVSFDefault);
        }

        private void Form1_Shown(object sender, EventArgs e)
        {
            trackBarRate.Minimum = -10;
            trackBarRate.Maximum = 10;
            trackBarRate.Value = svc.Rate;//Rate取值 -10  10
            trackBarVolume.Maximum = 100;
            trackBarVolume.Value = svc.Volume;//Volume取值 0100
            ISpeechObjectTokens sots = svc.GetVoices(String.Empty, String.Empty);
            int i = 0;
            foreach (ISpeechObjectToken sot in sots)
            {
                String str = sot.GetDescription(0);//得到语音名称|相当于sot.GetAttribute("name")
                comboBoxLanguage.Items.Add(str);
                if (str == svc.Voice.GetDescription(0)) comboBoxLanguage.SelectedIndex = i;
                i++;
            }
        }