音量已经开到最大了，而且也没有静音模式，麻烦帮看下是不是还有哪里要设置

speechSynthesizer.setParam(SpeechSynthesizer.PARAM_SPEAKER, "0");
// 设置合成的音量，0-9 ，默认 5
speechSynthesizer.setParam(SpeechSynthesizer.PARAM_VOLUME, "9");
// 设置合成的语速，0-9 ，默认 5
speechSynthesizer.setParam(SpeechSynthesizer.PARAM_SPEED, "5");
// 设置合成的语调，0-9 ，默认 5
speechSynthesizer.setParam(SpeechSynthesizer.PARAM_PITCH, "5");

speechSynthesizer.setParam(SpeechSynthesizer.PARAM_MIX_MODE, SpeechSynthesizer.MIX_MODE_HIGH_SPEED_NETWORK);
speechSynthesizer.setAudioStreamType(AudioManager.MODE_NORMAL);