cefsharp cannot play audio by javascript

I am writing a dictionary program using CefSharp by C#. When the dictionary page(i.e.[Longman-love][1]) is loaded I want it could play its pronounce automatically(by clicking the pronouce icon using JavaScript). Here are related codes: C# part: JavaScript part(I copyed it from web and added some ‘alert’s for debugging the program): The last alert sentence alert(‘will play’); showed but I could not hear anything. However,when I clicked the audio icon directly in the CefSharp browser, it could play the pronounce. How could I fix this problem? I am not a native English speaker, I hope you can understand me. Many thanks!