**4. Results**

The LDA topic extraction results concerning the first question reveal similar dimensions to those addressed in the literature on hearing loss. The twenty-one topics resulting from the LDA computation are shown in Table 1. The lists of words that make up a particular topic are displayed below the topic title for each theme. The finding suggests that the identified themes not only resembled the categorization of hearing loss diagnosis and treatments but also cover issues on topics relating to hearing loss.

We then examined the extracted 21 topics and merged similar topics. Finally, the topics were classified into five themes, which were "sudden hearing loss", "tinnitus", "noise-induced hearing loss", "hearing aids", "dizziness", "curiosity about hearing loss", "otitis media" and "complications of disease". Topics and words with probabilities for each topic are shown in Table 1.

**Theme 1. Sudden Hearing Loss.** *Four of the identified topics, namely Topics 3, 13, 17, and 22, pertain to sudden sensorineural hearing loss, commonly known as "sudden deafness", so the main theme derived from the four topics is labelled as sudden hearing loss. Specifically, this theme addresses causes, diagnosis, medication treatments, prescriptions, and e*ff*ects associated with both sudden hearing loss.*

Topic 3 contains the words related to the medication treatments of sudden sensorineural hearing loss: "steroid", "injection", "treatment", "drug", "prescription", "shot", and "sudden deafness". We found that, based on the selected keywords, the main concern is related to steroid use for the treatment of sudden deafness. Steroids taken orally or given by injection are commonly used to treat patients who experience sudden deafness. Topic 3 shows evidence that people with sudden hearing loss post questions to learn more about the effectiveness of treatment with steroid drugs and direct injections into their ears.

Topic 13 reflects diagnosis and test related to sudden hearing loss with keywords specifically "diagnosis", "cause", "hospital", "test", "result", "nose", and "infection". It is evident that patients who have been diagnosed with sudden deafness recently posted questions about what causes sudden deafness.

Topic 17 and 21 represent prescriptions and side effects, respectively. Terms such as "side effect", "treatment", "prescription", "drug", "worry", and "recovery" explain that patients with sudden deafness express concerns about the side effects of steroid and hearing recovery. A greater portion of patients diagnosed with sudden deafness have expressed concerns about the side effects of steroid use and have posted questions about whether their steroid treatment is appropriate in terms of frequency and dosage.

**Theme 2. Tinnitus.** *Four of the identified topics, namely Topics 1, 6, 15, and 19, pertain to tinnitus, so the central theme derived from the four topics is labeled as tinnitus. Specifically, the tinnitus theme addresses symptoms, causes, and treatments associated with both tinnitus and hearing loss.*


**Table 1.** The most probable keywords in the topic of LDA with 21 topics.

Topic 1 and 6 represent issues of hearing loss, with tinnitus symptoms and problems due to tinnitus such as "ringing", "buzzing", "sound", "loud", "noise", "sleep", "hissing", "night", "severe", and "stress". Interestingly, the keywords identified in the two topics show that questioners or patients in social Q&A detail their hearing problems with specific vibrations and sounds (e.g., "ringing", "buzzing" and "hissing"), and specify a level of severity when posting a tinnitus symptom. Tinnitus, commonly referred to as buzzing in the ears, is "often accompanied by hearing loss but not everyone with hearing loss experiences tinnitus" [44]. However, the results indicate that a significantly greater portion of patients who experience tinnitus are involved in the hearing loss topic. Additionally, patients seem to be more stressed at night due to tinnitus and worry that severe or persistent tinnitus is a sign of going deaf.

Topic 15 shows the keywords involved in treatments of tinnitus. This included words such as "treatment", "hospital", "doctor", "food", "audiologist", "pain", and "doctor". The topic results show that patients are in search of diverse tinnitus treatments, and specifically seek for good hospitals or doctors, and alternative treatments for tinnitus. We also found that, based on the selected keywords, effective food is a frequently occurring word, implying that tinnitus patients also search for foods to help reduce tinnitus.

Topic 19 represents a cause of tinnitus with keywords specifically including "infection", "drug", "earwax", "noise", "stress", and "medication". The topic results show that people want to understand what causes tinnitus. Patients who are su ffering from tinnitus want to know more about whether their recent illness, such as ear infection, ear wax, or stress, causes tinnitus. Additionally, patients with tinnitus post inquiries about the relationship between tinnitus and hearing loss, and particularly ask whether tinnitus can lead to hearing loss. Most importantly, the results show that many patients with hearing loss post questions whether exposure to loud noise causes tinnitus.

**Theme 3. Noise-Induced Hearing Loss.** *Topic 2 contains terms such as "loud", "music", "earphone", "headset", "cause", "damage", referred to as "noise-induced hearing loss". These words imply that users want to ask about the relationship between listening to loud music through earphones or headsets with a personal listening device and hearing loss. In addition, people want to know how long listening to music is safe for not getting hearing loss per day.*

The authors can observe the terms "shooting", "military", "gun", "explosion", "compensation", "degree", and "diagnosis", "hospital" in Topic 18. These terms imply that people who are exposed to excessive and continuous noise wonder and ge<sup>t</sup> the information whether and how they can ge<sup>t</sup> any compensation with their degree of hearing loss. Notably, South Korea has adopted a conscription system. Noise-induced hearing loss is a severe disease in the military because military personnel remain in a noisy environment for the completion of their missions. Thus, the prevalence of hearing loss and tinnitus in the military is higher than the general public [45].

**Theme 4. Hearing Aids.** *Topics 8, 11, and 16 were identified as hearing aids. Hearing aids are the most popular option of treating hearing loss for improving speech understanding. Topic 8 contains the words, "hearing aids", "cochlear implant", "handicap degree", "disabled", and "support". In South Korea, the registered disabled person with hearing loss gets the subsidy of their hearing aid expense every five years. People with hearing loss or their family members want to know whether their hearing loss degree gets financial support.*

In Topic 11, the authors also observe the term "cochlear implant" and "surgery". In a person with severe to profound hearing loss, hearing aids do not give many benefits. So, instead of hearing aids, cochlear implantation can help to improve speech understanding to people with severe to profound hearing loss. People want to ask about alternative interventions, such as cochlear implantation surgery, other than hearing aids.

Topic 16 consists of the keywords: "hearing aids", "recommend", "brand", "hospital", and "price". Those keywords indicate that patients post questions by asking for a specific recommendation for an excellent hearing aid with a reasonable price in social Q&A.

**Theme 5. Otitis media.** *Topics 4 and 10 include the terms related to hearing loss with symptoms of otitis media, such as "pain", "sore throat", "infection", "deafen", "headache" and "eardrum". Otitis media is an infection of the middle ear, and it is one of the most common disease in children [46]. The symptoms of otitis media are sore throat, night restlessness, fever, and ear pain [47].*

Topic 10 also contains keywords related to the treatment of otitis media, "hospital", "surgery", "medication", "test", "after". The results indicate that people asked about hearing loss after taking medication or undergoing surgery for otitis media. The term "hospital", "after", and "doctor" imply that, right after visiting doctors, users ask questions about otitis media treatment, such as drugs and surgery. Mild hearing loss can come with otitis media, and usually, hearing loss recovers after otitis media is cured. However, if otitis media occurs repeatedly, it causes permanent hearing loss [48].

**Theme 6. Dizziness.** *Topic 9 contains the words "dizzy", "cause", "headache", "awake", "morning", "severe" and "sudden" referred to as "dizziness". Topic 14 also contains the keywords "headache", "stress", and "dizziness" referred to as "dizziness". One of the most common cause of dizziness is problems of the inner ear. The vestibular system, which is responsible for balance, is located within the inner ear with the auditory system. There are many diseases that a*ff*ect dizziness and hearing loss, including severe cold, and bacterial or virus infections of the inner ear. In particular, Ménière's disease is a disorder of the inner ear that leads to dizziness and sudden hearing loss. The a*ff*ected ear may lead to progressive and*/*or permanent hearing loss [49]. Other symptoms of Ménière's disease are tinnitus, migraines, and nausea. Ménière's disease is very hard to diagnose due to the fact that not all of the symptoms are shown at the early stage [50]. These words relating to topic 9 may represent the symptoms of Ménière's disease.*

**Theme 7. Curiosity or general inquiry about hearing loss.** *Topics 5 and 20 contain a higher number of words relating to hearing loss itself. The authors could observe that users want to know about assessment results, such as the units (decibel) which are used for describing hearing loss. Additionally, the terms such as "stress", "nerve", "headache", "worry" imply that users ask about their symptoms relating to hearing loss.*

The terms "treatment", "hospital", "communication" "learning" imply that people went to the hospital to have assessments of their hearing, but they did not fully understand their hearing loss and how to treat their hearing loss. In social Q&A, they want to ge<sup>t</sup> the information about their hearing loss.

**Theme 8: Complications of disease.** *Topic 7 and 12 represent the terms "chronic", "anemia", "cancer", "thyroid", "hepatitis", "kidney" and "disease". All the diseases in topic 12 are related to hearing loss. Hearing loss is a side e*ff*ect of some chemotherapy drugs [51–54]. Additionally, anemia, iron deficiency, and thyroid hormone deficiency lead to hearing loss [55–58]. The hepatitis virus B and C are very strong risk factors of sudden sensorineural hearing loss [59]. Hearing loss is linked to chronic kidney disease [60], too. In social Q&A, patients or their family members seek the information about di*ff*erent complications leading to a hearing loss.*
