ト and ツ in English loanwords


When it comes to gairaigo, every time there's a consonant cluster or a final
one you generally add a -u to it. Glass=gurasu, plan=puran, story=sutoorii,
wrestling=resuringu. As far as I can tell, this is the case for everything
_except_ the clusters /tr/ and /dr/, and final /t/ and /d/. Dragon=DOragon,
dress=DOresu, trap=TOrappu, trick=TOrikku, apart(ment)=apaaTO, fight=faiTO.
What I'm guessing is that "tsurikku" would have one too many consonants, the
analogue "tsrick" doesn't sound great. Final ツ is a lot less popular but seems
to exist, when the word ends in /ts/ or /ds/. And of course when it'd be
/dzu/, it becomes /zu/ because of them being the same in Tokyo-ben, therefore
good=guddo but goods=guzzu.

I'm looking for papers that investigate this, it looks pretty interesting.




According to the following article, _-u_ was the most common vowel and there
has been change to _-o_. It further rationalizes the change using some theory.

  * 大滝靖司 [借用語における母音挿入の音韻論的解釈 ―共時的および通時的観点から―／](https://researchmap.jp/Ltd-Exp/published_papers/1028786/attachment_file.pdf), [音韻研究 第１５号](http://www.kaitakusha.co.jp/book/book.php?c=2015&l=ja), 2012.

Copying some relevant(-looking) passages and citations for later reference.

> 挿入母音U [ɯ] は最も出現頻度の高いことから「デフォルト」の挿入母音と呼ばれることがある。 U が最もよ く挿入されるのは、日本語の 5
> 母音の中で①内在時間長が最も短く、②聞こえ度が最も低く、③無声化が起こり やすいことから、最も母音が無いように聞こえるためである
> (窪薗1999:229-233) とされる。

> ここで上述の環境で母音挿入の変化が起きた要因を考察する。 まず、 ʦU から tO への変化 (10a) については、 初めはデフォルト挿入母音 U
> が支配的だったが、後に原語の子音/t/の閉鎖音としての素性の保持を優先するよう になり、 O が挿入されるようになったと説明できる。

  * 窪薗晴夫 1999『日本語の音声』東京：岩波書店
  * Kubozono, Haruo. 2002. Prosodic structure of loanwords in Japanese: syllable structure, accent and morphology. Journal of the Phonetic Society of Japan 6(1). 79-97.
  * Lovins, Julie B. 1975. Loanwords and the phonological structure of Japanese. Bloomington: Indiana University Linguistic Club
  * 澤田田津子 1985「外来語における母音添加について」『国語学』 143. 88-75.




I think you are right. This should be simply because Japanese had no sound
that was similar enough to "tu" and "du". As you know, phonetically speaking,
the タ-line is highly irregular:

> タ /ta/ ダ /da/  
>  **チ** /t͡ɕi/ **ヂ** /d͡ʑi/  
>  **ツ** /t͡su/ **ヅ** /zu/ (/d͡zu/)  
>  テ /te/ デ /de/  
>  ト /to/ ド /do/

Although Japanese people started to recognize トゥ (/tu/) and ドゥ (/du/)
relatively recently as "extended kana", these were not things available in the
past. If old Japanese people had added "u" unconditionally, trap would have
ended up with ツラップ, but /t/ and /t͡su/ must have sounded too different even to
their ears. So they had to use ト instead.

At the end of words, there are some irregularities like シャツ, バケツ, スーツ and ビーズ.
Perhaps people did not pay much attention to this because sentence-end vowels
were sometimes simplified even in ordinary Japanese.

