Inclusion Criteria in Phase 2  Occupational therapist  This study requires the subject to be between 18 and 80 years old. The subject needs to be Thai. The subject can communicate in the Thai language. Working as an occupational therapist in Ramathibodhi hospital. The subject is consent.  Head and neck cancer patients  This study requires the subject to be between 18 and 80 years old. The subject needs to have stable vital signs. The subject can make the body steady sit on the chair longer than 30 minutes. The subject is diagnosed with head and neck cancer and treated at Ramathibodhi hospital. Eating Assessment Tool (EAT-10) score is more than or equals 3. Montreal Cognitive Assessment (MOCA) score is more than or equals 23. The subject is consent.  Exclusion Criteria in Phase 2  Occupational therapist  Cannot participate in the experiment. The therapist denied or withdrew.  Head and neck cancer patients  Have pain around the examination area such as oral mucosa, tongue, and neck. Participate in chemotherapy. Cannot participant until the end of the experiment. The subject denied or withdrew.  Inclusion Criteria in Phase 3  Dysphagic Specialist  The age is more than 18 years old. The specialist is required to be Thai. The specialist can communicate in the Thai language. Working in oropharyngeal swallowing rehabilitation in the dysphagic unit at Ramathibodhi hospital for more than 3 years. The specialist has papers related to swallowing rehabilitation. The specialist is consent.  Observers  This study requires the subject to be between 18 and 80 years old. The observer can communicate in the Thai language. The observer needs to be Thai. Working in swallowing rehabilitation in Ramathibodhi hospital for more than a year. The observer is consent. Head and neck cancer patients The criteria are the same as the inclusion criteria of head and neck cancer patients in phase 2.  Exclusion Criteria in Phase 3  Dysphagic Specialist  Cannot participant in the experiment. The specialist denied or withdrew.  Observers  Have a relationship with software development. Cannot participate in the study until the end of the experiment. The subject denied or withdrew. Head and neck cancer patients The criteria are the same as the exclusion criteria of head and neck cancer patients in phase 2.