<Window xmlns="https://github.com/avaloniaui"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
        xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
        Height="300" Width="300"
        x:Class="AvaloniaUI.SpeechSynthesis"
        Title="SpeechSynthesis">

    <StackPanel Margin="10" Spacing="8">
        <TextBox x:Name="txtWords"
                 Watermark="Enter text to speak"/>

        <Button Content="Speak"
                Click="CmdSpeak_Click"/>

        <Button Content="Prompt Test"
                Click="CmdPromptTest_Click"/>
    </StackPanel>
</Window>

using Avalonia;
using Avalonia.Controls;
using Avalonia.Interactivity;
using Avalonia.Markup.Xaml;
using System;
using System.Speech.Synthesis;

namespace AvaloniaUI;

public partial class SpeechSynthesis : Window
{
    public SpeechSynthesis()
    {
        InitializeComponent();
    }
    private void CmdSpeak_Click(object? sender, RoutedEventArgs e)
    {
        using var synthesizer = new SpeechSynthesizer();
        synthesizer.Speak(txtWords.Text);
    }

    private void CmdPromptTest_Click(object? sender, RoutedEventArgs e)
    {
        var prompt = new PromptBuilder();

        prompt.AppendText("How are you");
        prompt.AppendBreak(TimeSpan.FromSeconds(2));

        prompt.AppendText("How ", PromptEmphasis.Reduced);

        var style = new PromptStyle
        {
            Rate = PromptRate.ExtraSlow,
            Emphasis = PromptEmphasis.Strong
        };

        prompt.StartStyle(style);
        prompt.AppendText("are ");
        prompt.EndStyle();

        prompt.AppendText("you?");

        using var synthesizer = new SpeechSynthesizer();
        synthesizer.Speak(prompt);
    }
}