visual studio 2010 c# reference

[garbmail10]

Hallo to all

I'm using visual studio 2010 c# on windows 7

In a program i use SpeechLib (located in C:\Windows\System32\Speech\Common\sapi.dll) with

SpVoice voice = new SpVoice();
voice.Speak("Hallo", SpeechVoiceSpeakFlags.SVSFDefault);
 

The voice was ok until i added System.Speech.Synthesis (located in C:\Program Files\Reference Assemblies\Microsoft\Framework\v3.0\System.Speech. dll) with

public SpeechSynthesizer _speaker = new SpeechSynthesizer();
_speaker.SpeakAsync(speechstring);
 

Even after i removed the second reference the voice has pretty worse quality
Is there anything i can do to fix it ?

Thanks in advance