Are there rules for 濁音化？


As far as I know, 濁音化 happens a lot when words are combined together. The
following are some examples I know.

  1. 三（サン）+ 階（カイ）-> 三階（サン **ガ** イ）
  2. 一（イチ）+ 匹（ヒキ）-> 一匹（イ **ッピ** キ）
  3. 猫（ネコ）+ 好き（スキ）-> 猫好き（ネコ **ズ** キ）
  4. 興味（キョウミ）+ 深い（フカイ）-> 興味深い（キョウミ **ブ** カイ）

To the best of my knowledge, cases like 1 and 2 are very common in Japanese.

It seems that consonants in ハ行, if after ち or つ , usually become semi-voiced
(半濁) . At the same time, ち or つ become っ (促音化).

  * 烈（レツ）+ 風（フウ）-> 烈風（レ **ップ** ウ）

Also, if after ん, these consonants appear to become semi-voiced as well.

  * 三（サン）+ 分（フン）-> 三分（サン **プ** ン）
  * 千（セン）+ 変（ヘン）-> 千変（セン **ペ** ン）

For other consonants, like those in カ行, there doesn't seem to be a general
rule, just as @Leebo mentioned. But fortunately, Some cases can be handled
using UniDic, a dictionary for Japanese morphological analysis.

Using MeCab and UniDic, we can parse 三階 and 三回, respectively.

[code]

    三      名詞,数詞,*,*,*,*,サン,三,三,サン,三,サン,漢,*,*,*,*,N3,*,数,サン,サン,サン,サン,0,C3,*,3985463396409856,14499
    階      名詞,普通名詞,助数詞可能,*,*,*,カイ,階,階,カイ,階,カイ,漢,カ濁,基本形,*,*,*,"B1S6SjShS,B1S6S8SjShS",体,カイ,カイ,カイ,カイ,1,C3,*,1545647094374912,5623
    
[/code]

[code]

    三      名詞,数詞,*,*,*,*,サン,三,三,サン,三,サン,漢,*,*,*,*,N3,*,数,サン,サン,サン,サン,0,C3,*,3985463396409856,14499
    回      名詞,普通名詞,助数詞可能,*,*,*,カイ,回,回,カイ,回,カイ,漢,*,*,*,*,*,"B1S6SjShS,B1S6S8SjShS",体,カイ,カイ,カイ,カイ,1,C3,*,1540974169956864,5606
    
[/code]

In the above 2 cases, 三 has a feature **N3** , 階 has a feature カ濁, while 回 has
*, which means no information. And according to [UniDic User
Manual](https://clrd.ninjal.ac.jp/unidic/UNIDIC_manual.pdf), some rules for
濁音化 for numbers are illustrated in a chart.

[![enter image description
here](https://i.stack.imgur.com/Z0QET.png)](https://i.stack.imgur.com/Z0QET.png)

According to this chart, we find the rule below:

> If the previous word has a feature of N3 and the next word is カ濁, then
> consonant (of the next word) **k** becomes **g**.

Thus, 濁音化 happens in 三階 but not in 三回.

And additionally, cases like 3 and 4 are much more tricky. 興味 ends with ミ and
猫 ends with コ. I can't see any point about how they can affect following
consonants.




I have never come across the term 濁音化, but clearly what you describe is called
連濁, translated as 'sequential voicing'. Since Timothy Vance, An Introduction
to Japanese Phonology, devotes a whole chapter to this subject, I don't think
it can be covered properly here. You should really consult the above-mentioned
book, or some other treatment of Japanese phonology. There are some general
rules like 'Lyman's Law' which states that a voiced obstruent inhibits
rendaku, e.g., oo + sora yields oozora, 大空, but oo + kaze yields ookaze 大風,
not the expected *oogaze (because kaze contains a voiced fricative, 'z'), but
it is a large topic.

