Abstract: Apnea or Sleep Apnea Syndrome is a condition when a person unconsciously stops
breathing during a sleeping state for longer than a certain time. Long-term and multiple apnea events induce various impairments. However, apnea detection in hospitals is an intensive and complicated procedure and this causes highly undiagnosed and low awareness of the disease. Existing wearable devices for apnea detections mostly used heartbeat signal patterns and SpO2 levels to detect the disease, however since apnea is a respiratory impairment, it is believed that using a breathing pattern is the most straightforward approach in apnea detection. Several recent studies investigated that swallowing frequency during sleep can increase along with the apnea severity. However, the number of wearable devices using swallowing to detect apnea is very limited. Thus, this study proposes a wearable system to recognize human contexts such as breathing, heartbeat pattern, and swallowing using an audio sensor. Experiments were conducted to compare and obtain the most suitable parameters for the system such as window sizes, types of audio feature values, and classification algorithms. The prototype of the device was built and able to detect breathing, swallowing, heartbeat, oral sounds, and body movement. The result shows the best accuracy of 76.9% using 1s window size and Mel’s Frequency Cepstral Coefficient (MFCC) features in contact microphone data.