are you using Android or iOS? If you're using Safari in iOS, the way Safari loads the audio file is after you click the button, so you need to wait for a few seconds for audio file to be loaded after you click the button. While on Chrome, the audio is played right away because the audio file is preloaded before you click the button.
Please also note that some audio files are not available.
As for Android, I do not have an Android phone to test right now.
October 24, 2015 at 2:36pm