1. Read some literature, understand the knowledge of music and mood, or the impact on people.

Depression significantly decreased in the peaceful music group compared to the sad music group after the intervention. Further, significant differences in heart rate variability were identified during the intervention among the groups. The change in low frequency (LF) in the joyful music group was lower than the other three groups; the change in high frequency (HF) in the peaceful music group was lower than in the tension and joyful music groups; and the change in LF/HF in the peaceful music group was lower than in the sad and joyful music groups. Additionally, the subsamples with high state anxiety experienced more change in HF while listening to tense music than to peaceful music, reflecting an upward trend after listening for 10 minutes. The findings indicate that listening to different genres of music induces different psycho-physiological responses. In the present study, participants with high-state anxiety registered elevated parasympathetic activity after listening to 10 minutes of tense and sad music. Simultaneous listening effects were detected only in joyful and peaceful music, which reduced subjective anxiety and depression. The results of the present study advocate that music interveners and clinical care providers select joyful, peaceful, and tense music to help alleviate the anxiety and negative emotions of their patients.

2. In addition to the literature, I learned some music-related knowledge and also used many apps related to our subject.

Among many mobile phone applications, we have selected five existing mobile phone applications. They are Pzizz, Relax Melodies, Calm, Stop, Breath, Think, Simple Habit. We used these five mobile phone softwares separately, and the sound types they used are very similar.

Through analysis, it is easy to find that these software use the sound of nature or the sound of everyday scenes as background music. Use these background music to match the sound of reading aloud or piano and other instruments. Users rated these mobile apps after use and gave a high score of 4.7. In the comment section of the APP Store, most of the users said that this music helped them relax their mood, improve their attention, and bring them a better sleep.

3.In addition to Arduino, I learned about other sensors online, some of which can be used in our design

1. Electret Microphone：This can be installed in a test tube or flask
2. https://core-electronics.com.au/sensors.html This is a website that sells various sensors, I will buy some sensors

According to the observation method I learned in the HCI course, I will take the bus, record the observation data according to my own experience, and count the observation results. I will do some preparations before observing. First, I will prepare a pen, a form, and even interview passengers and make recordings. I will also try to take pictures.

The form will have the following content

Date&Time Location How many people in bus GET ON Get off

I will also record the age and characteristics of the passengers, what they are doing on the bus, what they did when they got on the bus, and what they did when they got off the bus.

Because of the special circumstances, we cannot go out now, so Lorna taught us some other observation methods. For example: Using YouTube (and Online Video) for (Teaching) Observational Studies (added by Robin Smith). I think this method is to find a video and then record your observation notes by watching the video. But I am more puzzled about how to choose the right video among many videos.

Watching a video has some advantages than going to the field. For example, during a field trip, if there were many people at the time, we could not observe the behavior of each person, and the video can be watched repeatedly, so we can observe and record the behavior of each person. The advantage of watching a video over a document is that the document is susceptible to the subjective views of the author.