Would copying registry entries to get access to all installed TTS voices be against the MS TOS?

Question

Hello,

I'm building an accessibility app that uses TTS voices already installed on a Windows 10/11 machine. However, GetInstalledVoices() provided by the SpeechSynthesizer class only gives me two options despite having installed German, English, and Dutch language packs. I need at least one voice per language to be available.

After some research, I discovered voices are registered at different registry locations: HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Speech\Voices and HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Speech_OneCore\Voices. Unfortunately, only the voices in the first location are accessible by the SpeechSynthesizer.

All solutions I can find for this suggest I copy the voices from one location to the other. However, I'm worried this might be against the Microsoft TOS.

Answer 1

You don't need to copy registry keys with SpeechLib

You can use SpObjectTokenCategory.SetId with the 2nd registry path to get the voices.

Test :

// Add reference to : Microsoft Speech Object Library (SAPI)

At beginning :

SpVoice voice = new SpVoice();

Then :

{
    ISpVoice pVoice = (ISpVoice)voice;
    SpObjectTokenCategory otc = new SpObjectTokenCategory();
    //otc.SetId("HKEY_LOCAL_MACHINE\\SOFTWARE\\Microsoft\\Speech\\Voices");
    otc.SetId("HKEY_LOCAL_MACHINE\\SOFTWARE\\Microsoft\\Speech_OneCore\\Voices");
    ISpeechObjectTokens tokenEnum = otc.EnumerateTokens();
    int nTokenCount = tokenEnum.Count;
    Console.WriteLine("Number of voices: {0}", nTokenCount);
    foreach (ISpeechObjectToken sot in tokenEnum)
    {
        Console.WriteLine("Voice : {0}", sot.GetDescription());
        {
            pVoice.SetVoice((ISpObjectToken)sot);
            try
            {
                uint n = 0;                       
                pVoice.Speak("Hello! This is a test", 0, out n);                        
            }
            catch (System.Exception ex)
            {
                Console.WriteLine("Cannot speak with the voice : {0}", sot.GetDescription());
            }
            Marshal.ReleaseComObject(sot);
        }
    }
}