Why is there an 'ear' radical in the character for smell? 闻 聞
I find this pretty confusing. Perhaps there is a fun story behind it?
「聞」(Baxter-Sagart OC: /*mu[n]/) is comprised of semantic「耳」(ear) and phonetic「門」(/*mˤə[r]/), indicating the meaning to hear. For example,「新聞」means news (literally meaning new information passed on by hearing/reading/etc.)
「門」does not play a meaning role in「聞」. For that matter, it does not play a meaning role in「問」, either.
To smell is a semantic extension. For example, in English, there's something fishy going on is used to describe a situation which is not quite right, literally referring to the smell of fish, but metaphorically referring to someone picking up information about their surroundings and deducing that something feels off.
NOTE: This is a hypothesis, not a fact.
The complex form, 聞, has a rather straightforward ideogrammatic interpretation as a pair of doors (門) with an ear (耳) presenting itself within the space beneath them, suggesting a human placing or centering their ear at or within the frame of the door pair's (door bottom)-(floor top) gap to hear sound issuing from the space behind said door. (This, in addition to that 門 is phonetically similar to 聞.) Hence, it has the meaning of hearing, i.e. hearing sound (音), perhaps whatever is going on on the other side of the door (i.e. snooping).
This element is used in more complex pieces with the meaning hearing - e.g. see the compounds section on Wiktionary:
e.g. 但聞. These suggest that, in a sense, the notion of "hear" became more generalized to the application of other sense organs - such as the nose - to an object of interests as well, essentially, to, more generally, "hear a smell" with the nose. It's generalized hearing, if you will, and carries the cognition of sensation or detection as a concept being a generalization of the notion of gathering information through the employment of the ear.
Baidu has this:
“闻”字在先秦时期已经被用来表示嗅到，《韩非子 · 十过》有**“闻酒臭而还”。我相信当时口语中表示嗅到的词与“闻”同音**，但没有专字，所以借用“闻”字来表示。这种现象在汉字中很普遍，如“朋”、“来”、“其”、“而”等等。如此观之，“闻”表示“嗅到”有可能是假借义。由广变窄，变专的过程。文学接受进入高潮阶段的一种更高境界，是指读者在阅读文学作品，与之形成共鸣，并达到净化后进入的更高阶段，包括潜思默想、洞悉宇宙奥妙、体悟人生真谛和提升精神境界等状况与过程。 我个人简单认为： 领悟就是心灵受到某种触动，而使智慧知识上升等级的过程。
Are the senses really all 1 sense? Is everyhting just in our minds? I recently read that the structures known as tastebuds are found in many other places in our bodies, apart from our mouths.
见 is see, but 听见 is hear.
There is a condition known as synesthesia. If you suffer from this, you may smell music, hear tastes.