代码：

#include "mainwindow.h"
#include "ui_mainwindow.h"

MainWindow::MainWindow(QWidget *parent):QMainWindow(parent),ui(new Ui::MainWindow)
{
    ui->setupUi(this);
    connect(ui->pushButton,&QPushButton::clicked,this,&MainWindow::test);
}

MainWindow::~MainWindow()
{
    delete ui;
}
void MainWindow::test(){
    QString str="欢迎您";
    this->ui->lineEdit->setText(str);
    QTextToSpeech *Speecher=new QTextToSpeech;
    const QVector<QVoice> voices = Speecher->availableVoices();
      for (QVoice voice : qAsConst(voices)) {
          if(voice.gender() == QVoice::Female)
          {
              Speecher->setVoice(voice);//选择女生
              break;
          }
      }
    Speecher->setRate(0);//调节阅读速度，取值范围为-1.0到1.0
    Speecher->setVolume(1.0);//    调节阅读声音大小，取值范围为0.0到1.0
    Speecher->say(str);
}

 ui设计：