Apple today released the fifth beta of iOS 7.1 to registered developers for testing purposes



From MacRumors:

According to the release notes, iOS 7.1 beta 5 includes new natural-sounding Siri voices for English (Australia), English (United Kingdom), Japanese, and Chinese (Mandarin - China). It also notes that a compact version of Siri is bundled with the release for the new languages, but can be expanded to the more natural voice after install.The iOS device initially uses a compact voice for Siri. After you have configured a Wi-Fi network and have the device connected to a power source, iOS will automatically download and install a higher quality version.

  Apple Releases iOS 7.1 Beta 5 to Developers With Siri Language Improvements