tashkil Tashkil are the various diacritics that are attached to Arabic letters to indicate features including vowels, gemination, and absence of any vowels. Arabic texts are typically written without tashkil, as fluent speakers can comprehend the text by automatically filling in these diacritics. Image at right: Arabic text with tashkil. The human brain is exemplary at filling in these diacritics, despite the fact that there is an average of 11.6 possible diacritizations for every non-diacritized word (Debili et al., 1998). That’s a lot of possible choices. Automated systems, such as the one behind ReadSpeaker’s text-to-speech technology, are quite good at determining the diacritics for particular words. However, a computer is no replacement for a fluent speaker and will consequently make more errors than a fluent speaker. This is why, when listening to Arabic TTS, reading a text written without tashkil, a fluent speaker will be able to determine where exactly the errors are. Whilst the ReadSpeaker team can fix the pronunciation of individual words in specific locations, any new texts written without tashkil will contain new pronunciation errors on the basis of the computer algorithm. How can you help improve the quality of the Arabic voices and decrease the number of errors? By writing texts with tashkil! This may be time-consuming, but at the end of the day, it’s beneficial to everyone. The ReadSpeaker voices improve, and more people can read the Arabic text, as texts written without tashkil are much more difficult for non-fluent (and possibly non-native) speakers of Arabic to read. Help our Arabic voices: Write with tashkil!