## 5 Discussion  
There are studies that have conducted perceptual training to improve the tone ability in Chinese perception and production; however, the content of the learning is mainly monosyllabic and disyllabic. A study that described the effects of perceptual training showed that after two weeks of perceptual training using disyllable words, the tone perceptual ability improved by 21% and lasted for over six months [31]. Studies have also divided participants into groups to measure the learning effect of the perceptual training and pronunciation practice, showing that when using monosyllabic words to perform perceptual and pronunciation training, perceptual training has a significant effect on improving perceptual ability, but the improvement in pronunciation ability is much less than that achieved by pronunciation practice [32]. Similarly, pronunciation practice is effective at improving monosyllabic tone pronunciation; however, the effect on improving monosyllabic tone perception is lower than that of perceptual training. However, using the application to practice disyllable word perception and pronunciation by imitating a model voice with pitch tracking shows that it is effective to improve pronunciation ability only with perceptual training. Training only in perception is sufficient for improving the tone perception and pronunciation in disyllabic words [33].  
There are various factors that can affect the results of the tone pronunciation experiment, such as the training time, individual differences among learners, learning experience of participants, etc. However, considering the reasons why the two studies that compared perception and pronunciation training described above led to different conclusions, we speculate that using monosyllabic or disyllable words and training with an application or a teacher is key. Training with a teacher can give the learners a proper opinion and help them to avoid pronunciation errors when practicing pronunciation. As shown in our experimental results, pronunciation practice with only the application may lead to fossilized errors. Furthermore, using monosyllabic words to perform perceptual training does not focus on the relative pitch and categorization perception of tones. Although the participants in the study could generally distinguish four tones in monosyllabics, recognizing and imaging the Mandarin Chinese tones correctly was still difficult for them.  
Based on cognitive psychology theories, the perceptual training app we developed examines the learning content, conducts experiments, and optimizes the perceptual training tasks and application interfaces that help users in learning Mandarin tones. The results of the evaluation experiment showed that the perceptual training application user's cognitive ability was improved, and the tone pronunciation errors were reduced. However, a participant who had a high correct answer rate (93.33%) in the disyllabic pronunciation task after training with perception questions performed worse (83.33) in the disyllabic pronunciation task after practicing their pronunciation instead of perception. Therefore, to support pronunciation practice to improve tone production, the task design and feedbackof pronunciation practice with the application should be based on considering the tone understanding and categorization, error correction, vocal cord exercises, etc.