I found that there are two different pronunciations for the [ɸ] phone. For example, in Japanese compare those two pronunciations for same word 冬 (for which I believe will has [ɸɯjɯ] as phonetic transcription):
- https://jisho.org/search/%E5%86%AC. To my ear, this one sounds more like [pʰɯjɯ].
- https://translate.google.com/#view=home&op=translate&sl=ja&tl=en&text=fuyu. . To my ear, this one sounds more like [kʰɯjɯ].
In this wikipedia page, which provides the audio sample for the sound (near the top right of the page), I also found that phone is pronounced much similar to the first link in the list above.
However, some other sources suggest that the pronunciation link in second link is also common. For example, this link: http://www.guidetojapanese.org/learn/grammar/hiragana provides pronunciation for /hu/.
So which one is correct, or both?
Note: I'm a Vietnamese native speaker and in our country, almost anyone can spot the difference between the two pronunciations in the links listed above.