Loanwords not being pronounced in a normal moraic rhythm?


Here's a spectogram of a speaker's rendition of “プロトタイプ” from English
“prototype”, collected from
[_Forvo_](https://forvo.com/word/%E3%83%97%E3%83%AD%E3%83%88%E3%82%BF%E3%82%A4%E3%83%97/#ja)

[![purototaipu](https://i.stack.imgur.com/89GsM.jpg)](https://i.stack.imgur.com/89GsM.jpg)

It should be clear from this spectogram that the _pu_ -mora is pronounced in
half a mora; the mora-length in this segment is about 0.16 ms and _pu_ takes
about 0.08 ms; the entire _tai_ is also pronounced in about 1.5 moræ.

I've definitely encountered this multiple times in speech, and it wasn't hard
to find examples on _Forvo_ at all. I couldn't find any published research on
the matter; is this normal? I've heard “ナイス” from English “nice” pronounced
with _nai_ as seemingly one mora, and it again wasn't hard to find examples of
this on _Forvo_ and confirm it with acoustic analysis.




Not an expert, so I cannot cite any research, but I think what you are
observing is the vowels not getting pronounced. English does this all the
time, and "prototype" is a case in point where "p" is not followed by a vowel,
but there are plenty of examples of this in Japanese native words. See
[母音の無声化](https://ja.wikipedia.org/wiki/%E6%97%A5%E6%9C%AC%E8%AA%9E%E3%81%AE%E9%9F%B3%E9%9F%BB#%E6%AF%8D%E9%9F%B3%E3%81%AE%E7%84%A1%E5%A3%B0%E5%8C%96)
in Wikipedia that describes some rules along with examples. Consider くつ vs
くうき.

As @naruto points out in a comment, [What are the rules regarding "mute
vowels" ("u" after "s" and "i" after
"sh")?](https://japanese.stackexchange.com/questions/1095/what-are-the-rules-
regarding-mute-vowels-u-after-s-and-i-after-sh) covers this in much more
depth.

