“…Ear wax, also called cerumen, is an important protective substance produced by glands in the skin of the ear canal along with skin cells that are shed daily, just like skin cells everywhere in the body. Cerumen exists the ear canal on its own during showering, swimming, and normal everyday activities and carries with it other matter that may have entered the canal. Cerumen’s main functions are to protect the delicate skin of the ear canal from damage by moisture and to fight outer ear infections such as swimmer’s ear.”
耳屎，也稱為耳垢，是耳道皮層上的腺體分泌來保護耳道的物質，加上耳道上新陳代謝後掉落的皮層死亡細胞。
耳垢主要的功能是保持耳道乾爽，並保護耳道皮層不被感染。
“The ear canal is about 1 inch long(24mm). The outer one-third of the canal is made up of cartilage, whereas the inner two-thirds is made of bone. The ear canal is lined with skin, much like the skin that covers the rest of the body, but there are some important differences.
The external ear has a unique self-cleaning mechanism. Like all skin of the body, outer layers of skin cells are lost every day. In the ear, these cells migrate outwards(from eardrum to ear canal opening) carrying debris with them. They become part of cerumen(ear wax) and extrude on their way from the ear opening. The wax is key to protecting the ear canal skins.
Cerumen glands are similar to both mammary glands and sweat glands. The cerumen itself had several functions. It helps prevent outer ear infection because it:
1. Protect the skin from water…
2. Is slightly acidic, making bacteria growth difficult, and
3. Contains antimicrobial protein that attack bacteria.
Together these factors contribute to an antibacterial and antifungal effect cerumen.”
外耳有自動清潔的機制。
耳道表面有一層皮層細胞，每天新陳代謝死亡剝落下來的皮層細胞，就會往耳朵外面的方向挪動。
耳垢分泌腺和乳腺及汗腺類似，它的分泌物和死亡剝落的耳內皮層細胞，共同構成了耳垢，用以下幾種機制保護外耳：
1. 耳垢防水。
2. 耳垢俱微酸性，可抑制細菌的繁殖。
3. 耳垢內含有抗菌的蛋白質。
因此，耳垢有抵抗細菌和真菌的功能。
(耳垢會自然往外移動，可以防止耳道阻塞，基本上不需要去挖它。挖耳垢，反而可能會把耳垢往內堆，而且不小心如果刮傷耳道，則容易導致感染。至於如果有小蟲子跑進去或感覺塞往了，最好找耳鼻喉科去處理。)
Age-related hearing loss.
年老的重聽。
“Sensorineural hearing loss that occurs in older adults is called presbycusis…The degree and age of onset of presbycusis tend to be hereditary, and men are disproportionately affected. Age-related hearing loss has a great impact on the quality of life of tens of millions of older people and is closely associated with all forms of dementia.”
年老時重聽程度和遺傳有關，在比例上，發生在男性身上比女性多。重聽和失智症相關(但非因果關係)。
“Aging changes the cochlea microscopically in four known ways: loss of hair cells and their supporting cells; loss of auditory nerve cells(that carry signals to the brain); degeneration of the stria vascularis(part of the cochlea that maintains chemical and bioelectric balance); and thickening of the basilar membrane(which normally vibrates freely). One of the rare causes of presbycusis is mutation of a mitochondrial gene…”
年老的重聽。是耳蝸的老化導致，有四種原因：
1. 毛細胞或相關細胞功能喪失。
2. 聽覺神經細胞功能喪失。
3. 耳蝸血管紋退化。
4. 基底膜變厚無法靈活震動。
至於因為粒線體基因的突變，這種年老的重聽則很罕見。
“At the time of writing, there is no cure for presbycusis or any type of nerve deafness.”
截至目前為止，老化導致的重聽(和神經性的耳聾一樣)，都沒有任何有效的治療方法。
Noise-Induced Hearing Loss
噪音引起的聽力喪失。
“Exposure to loud noise is the second leading cause of hearing loss. Noise-Induced Hearing Loss(NIHL) can occur at any age…
The louder the noise and the longer the exposure, the more damage it causes to the hair cells of inner ear…
Current music player…Earbuds are closer to the eardrum than head phones and can cause more damage. As a general rule, music played through earbuds or headphones should not be audible to anyone else(keep the volume down) and should not played for more than two hours at a time(keep the duration down as well). Another general rule: if your ears ring after exposure, you have already caused some damage.”
曝露在更大的噪音之中、曝露在噪音的時間愈久，對耳朵毛細胞的傷害愈大。
用耳機聽音樂的時候，聲音要愈小愈好，持續的時間要愈短愈好。如果在用耳機聽音樂的時候，旁邊的人也聽得到，那就明顯太大聲了。另外如果在聽完，耳朶會嗡嗡作響，那代表已經對耳朵造成傷害了，耳機音量太大了。
Tinnitus, ringing in the ears.
耳鳴。
“Tinnitus is the sense of hearing something when there is no related external sound. Nonetheless, tinnitus is real; there are well-known causes for tinnitus and it can be measured. Tinnitus is not a disease but a symptom of physiology.”
耳鳴本身並不是疾病，而可能是身體某些不正常所顯示的症狀。
“…It seems that the actual loudness of their tinnitus does not determine whether people feel that it is ruining their lives. The amount of distress caused by tinnitus is instead related to anxiety and depression. In other words, anxiety and depression do not cause tinnitus but make it seem worse. A tinnitus cycle can develop where anxiety, depression, and loss of sleep make tinnitus more debilitating and the worsening tinnitus makes the anxiety and depression more severe.”
耳鳴音量的絕對大小，對個人生活影響的大小，並沒有必然的關係。耳鳴所造成的焦慮和憂鬱，才是患者所感受到的壓力。換句話說，耳鳴不必然造成焦慮和憂鬱，但容易有焦慮和憂鬱傾向的人，會更感到耳鳴的嚴重性。耳鳴、焦慮和憂鬱、失眠等三者，會形成一個交互影響的惡性循環。
“The realistic goal of treatment of tinnitus of chronic subjective tinnitus is management rather than cure. That is, the hope is to reduce the severity and allow the patient to understand and feel control of his or her tinnitus rather than to feel oppressed and controlled by it…”
面對耳鳴，最合理的目標不是根除它，而是要去管理它；理解它，接受它，跟它和平相處。避免因為耳鳴而引發心𥚃不必要的焦慮和憂鬱。
“Caffeine, Alcohol, and smoking make tinnitus worse…”
耳鳴的人要避免喝有咖啡因(咖啡、茶、可樂等等)的飲料、不要喝酒，不要抽煙。
“Sleep is important for your overall health. If you have a thick neck, snore loudly, or weigh more than you should, you may need to shed some pounds…”
有好的睡眠品質和維持適當的體重，也很重要。
Sound Therapy.
耳鳴的聲音療法。
“Sound therapy uses external sources of sound to reduce the severity of tinnitus…
Following are some methods of sound therapy used to promote sleep.
1. Everyday background sounds such as music, fans, air conditioners, humidifiers, air filters(or political speeches).
2. Generic sound generator can play recordings of birdsong, trains, a babbling brook, or the ocean through headphones or pillow speakers.
3. Customized sound generation(also called wearable maskers) look like hearing aids…
(不寫了，自行參閱)
*：Thomas J. Balkan & Kevin D. Brown, The Ear Book, a complete guide to ear disorder and health, 2017, John Hopkins University Press
2023/7/30 The Ear Book, a complete guide to ear disorder and health Damakey
