About the Pronunciation of 'hypothesis'
As you known, the phonetic symbol for 'th' of 'hypothesis' is same as the 'th' of 'thank' (I cannot print out that phonetic symbol, so here I just use /0/ as the symbol.)

The problem is that 'th' in hypothesis sounds like /f/ rather than /0/ for me. I also recorded my pronunciation for this word, and the result is same. Although I tried to pronounce /0/, but it still sounds like /f/.

Do you notice that phenomenon? You can find another person to read this word and you listen. It seems difficult to tell /fi/ and /0i/. But easy to tell /faen/ and /0aen/, e.g word 'fan' and 'thank'.

I am not sure whether it's common or there is problem in my ear.
Thanks for your anwsers! in advance :)

Question

About the Pronunciation of 'hypothesis'
As you known, the phonetic symbol for 'th' of 'hypothesis' is same as the 'th' of 'thank' (I cannot print out that phonetic symbol, so here I just use /0/ as the symbol.)

The problem is that 'th' in hypothesis sounds like /f/ rather than /0/ for me. I also recorded my pronunciation for this word, and the result is same. Although I tried to pronounce /0/, but it still sounds like /f/.

Do you notice that phenomenon? You can find another person to read this word and you listen. It seems difficult to tell /fi/ and /0i/. But easy to tell /faen/ and /0aen/, e.g  word 'fan' and 'thank'.

I am not sure whether it's common or there is problem in my ear.
Thanks for your anwsers! in advance :)

Answer

Zhen, I can see from your picture that you are just a baby now.
Even American kids your age nomally have problems with the "th" sound.  I'm surprised you even know how to use a computer.

Don't worry-- as you get older, you'll be able to make more sounds like us adults.

Answer

Here's what to listen for:

The th/θ has a slight hiss and sounds sharper, whereas the f is slightly muffled and puffy.  Think of the θ as an s which has slipped forward, not an f which has slipped back.

By the way, there is a British accent in London (nooo, not all of London) which has replaced θ with f, so "south" sounds like "souf", and "three" sounds like "free".

Answer

the sound for /0/ as in THANKS  is interdental (your tongue goes between your upper and lower teeth)

the sound for /f/ as in FAN is labio-dental (your upper teeth touch your lower lip)


as you can see, the difference is mainly articulatory

Answer

Aout pronounciation, our teacher told us many years ago "stick your tongue out" 
not like cow ofcourse, but it's tip should be between teeth,

Answer

To a native English speaker, the "th" in "hypothesis" sounds exactly like the "th" in "thank" (and the accent is on the second syllable--"hy-PO-the-sis").