语音合成时怎么选择播报的声音？我用sdk中

String ttsTextModelFilePath =

                getApplicationContext().getApplicationInfo().dataDir + "/lib/libbd_etts_text.dat.so";

        String ttsSpeechModelFilePath =

                getApplicationContext().getApplicationInfo().dataDir + "/lib/libbd_etts_speech_female.dat.so";

        speechSynthesizer.setParam(SpeechSynthesizer.PARAM_TTS_TEXT_MODEL_FILE, ttsTextModelFilePath);

        speechSynthesizer.setParam(SpeechSynthesizer.PARAM_TTS_SPEECH_MODEL_FILE, ttsSpeechModelFilePath);

不起作用，有谁能替我解答一下？