Evaluating Arabic Text-to-Speech synthesizers for mobile phones

Text-to-Speech (TTS) synthesizers are useful tools for the visually impaired people. However, current TTS synthesizers are lacking in several aspects. Different factors of TTS synthesizers can be evaluated for the use in specific applications. As part of an undergoing project for building an Arabic navigation system for the blind, we need to choose the best Arabic TTS to be used within the system. For that purpose, we conducted an evaluation of five Arabic TTS synthesizers for mobile devices, namely VoiceOver, Uspeech, Acapela, Adel, and SVOX. First, we evaluated their intelligibility and naturalness using the modified Mean Opinion Score (MOS) scale with visually impaired subjects. The results showed the subjects´ biasness to VoiceOver and Acapela since they are familiar with. Due to the biasness of the MOS test results, we performed another evaluation, namely Semantically Unpredictable Sentences (SUS) test, to evaluate the intelligibility of the systems. Our results show that Adel has the highest score among otherTTS while Acapela has the lowest score.