Wow Text-To-Speech speed not work?

the tts speed and volume does not work in wow on ubuntu? can change and hear but too slow…

this api (enable tts first) demonstrates the same problem (changing speed/volume not work) C_VoiceChat.SpeakText - Warcraft Wiki - Your wiki guide to the World of Warcraft /run C_VoiceChat.SpeakText(0, “Hello world”, Enum.VoiceTtsDestination.LocalPlayback, 0, 100)

also tried manually changing settings file (tts-cache-account.txt) and deleting/resetting it, nothing changes speed!?

just wondering if anyone has got it working or
works fine on windows…

thanks