I was watching a Hangul tutorial the other day, and noticed something interesting about English: the "s" sound in the word "stand", is slightly different from the "s" sound in the word "sun".

Let me explain.

Take the word "beet" and "bit" for example. When you try to pronounce the word "beet", the articulation of the vowel happens in the back of your mouth, it is pronounced longer, and your lips stretch towards the side. This in phonology is known as "tenseness". In contrast, in pronouncing the word "bit", the articulation of the vowel happens in the front of your mouth, it is pronounced shorter, and your lips stays in a neutral position. This is known as "laxness".

The same rule applies to consonants as well.