google voice synthesis Speed ​​control, language code API, help!

            
I use http://translate.google.com/translate_tts?tl=zh_cn&q = "need synthesized voice" doing speech synthesis, but the synthesis of Speed ​​too fast, how to control the rate of speech? Tl languages ​​and area code if Baidu same code? Thank you!
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Add: the synthesized voice echo heavy, how to solve it?
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