What are the pitch-accent rules for compound nouns?

Question

I've been trying to learn the pitch-accent of standard Japanese, but this is more difficult as it should be as it's hard to find good learning resources that provide proper descriptions of how the accent works. For many words, this isn't too much of a problem, as I've found that good monolingual Japanese dictionaries use numbering notation to mark the location of pitch-accent. However, dictionaries don't tend to include many compound nouns, as their meaning can readily determined through their constituent parts.

I've been trying to find what rules govern the location of pitch-accent in compound words, but have found various conflicting descriptions.

One approach says that:

If N2 is three morae long or longer, a compound noun accent falls on the initial syllable of N2; e.g. 携帯電話 is pronounced けいたいでꜜんわ.

But another approach that I have found says that:

The compound accent falls either on the rightmost, nonfinal foot of the compound, or on the original accent position of the second noun; in which case 携帯電話 would presumably be pronounced either as けいたꜜいでんわ, or else without any downstep, as 電話 is unaccented.

These two descriptions seem to be conflicting, so I'm not sure what the actual rules are here. Would anyone be able to offer any advice on this matter? Thanks!

Answer 1

So, Toshihiko's answer gives the answer for the normal case, but there is a whole other facet of this issue:

Do two nouns always compound or not?

And the answer is that in many cases they do not. I can't list out all the cases, but the major categories to pay close attention to are:

1. N2 is somehow locative

E.g.,

• ロシア南部　→　ロ＼シア・ナ＼ンブ
• ロシア国境　→　ロ＼シア・コッキョー￣
• ヨーロッパ各国　→　ヨーロ＼ッパ・カ＼ッコク

You may occasionally hear the compounded versions of these, but not-compounded is more common.

2. N2 is a transitive suru-verb (他サ)

subject+verb → no compounding

• 当局発表　→　ト＼ーキョク・ハッピョー￣

object+verb → compounding

• 結果発表　→　ケッカハ＼ッピョー

• 乱数調整　→　ランスーチョ＼ーセー

• 再建検討　→　サイケンケ＼ントー

• 承認申請　→　ショーニンシ＼ンセー

• 自動車販売　→　ジドーシャハ＼ンバイ

  _{※ However, there are some exceptional transitive N2 verbs which cause the phrase to not compound:}

  • _{〜禁止（e.g., タバコ禁止　→　タバコ￣・キンシ￣、　撮影禁止　→　サツエー￣・キンシ￣）}
  • _{〜中止（e.g., 開催中止、渡航中止）}
  • _{〜防止（e.g., 蔓延{まんえん}防止、再発防止）}
  • _{〜改正（e.g., 憲法改正、特措法改正）}
  • _{〜独占（e.g., 権力独占、市場独占）}
  • _{〜開催（e.g., 大会開催、オリンピック開催）}
  • _{〜獲得（e.g., タイトル獲得、金メダル獲得）}
  • _{〜設立 (e.g., 水泳部設立、組織設立）}

modifier+verb → compounding

• 急激上昇　→　キューゲキジョ＼ーショー
• 全国販売　→　ゼンコクハ＼ンバイ

3. N2 is an intransitive suru-verb (自サ)

subject+verb → no compounding

• 雨雲発達　→　アマグモ￣・ハッタツ￣
• 社長辞任　→　シャチョー￣・ジニン￣
• 景気後退　→　ケーキ￣・コータイ￣

modifier+verb → compounding

• 一時帰国　→　イチジキ＼コク
• 引責辞任　→　インセキジ＼ニン

4. N2 is a both transitive and intransitive suru-verb　(自他サ)

subject/object+verb → no compounding (usually, especially when it's a novel combination)

• 所得減少　→　ショトク￣・ゲンショー￣ (or ショ＼トク・ゲンショー￣）
• 問題解決　→　モンダイ￣・カイケツ￣ (* see below)
• 感染拡大　→　カンセン￣・カクダイ￣ (* see below)

But it seems like if they get lexicalized enough they can compound:

• 人口減少　→　ジンコーゲ＼ンショー (I think this is always compounded)
• 問題解決　→　モンダイカ＼イケツ (I list this in both sections because you hear both)
• 感染拡大　→　カンセンカ＼クダイ (You used to hear this more but it seems like everyone has settled on not compounding it)

modifier+verb → compounding

• 急激減少　→　キューゲキゲ＼ンショー

Answer 2

A first, I write the initial word in compound nouns ''N1'', and the second word ''N2''.　　

The original pitch-accent pattern of N2 governs the location of pitch-accent in compound words.

If N2 is 3 morae long or longer

(1) In case N2 has the accent-fall in the middle, or on the initial syllable of the word, the compound noun keeps the location of N2.

• [たまご]{LHL}（卵） -> [おんせんたまご]{LHHHHHL}（温泉卵）
• [ひこうき]{LHLL}（飛行機） -> [かみひこうき]{LHHHLL}（紙飛行機）
• [はみがき]{LHLL}（歯磨き）it means toothpaste -> [やくようはみがき]{LHHHHHLL}（薬用歯磨き）
• いいんかい{LHLLL}（委員会）-> よさんいいんかい{LHHHHLLL}（予算委員会）
• [オリンピック]{LHHHLL} -> [ソルトレイクシティーオリンピック]{LHHHHHHHHHHHHHLL}
  
  However, some exception can be hit upon.
• [せんげん]{LHHL}（宣言） -> [ポツダムせんげん]{LHHHHLLL}
• [じょうけん]{LLHHL}（条件） -> [あくじょうけん]{LHHHLLL}（悪条件）
• [なっとう]{LHHL}（納豆）-> あまなっとう{LHHLLL}（甘納豆）
• [やきゅうじょう]{LHHHHHH}（野球場） -> [けんえいやきゅうじょう]{LHHHHHHHHHH}（県営野球場）
  
  There seems to be too many exceptions to call it rule.
  Some scholars or teachers may insist that it is the rule for the accent to fall on 1st syllable of N2, e.g.あくじょうけん{LHHHLLL}, and おんせんたまご{LHHHHHL} is rather exceptional.
  

(2) In case N2 has the accent-fall at the last syllable, or has no accent fall, the compound noun accent falls on the first syllable of N2.

• [でんわ]{LHH}（電話）-> [けいたいでんわ]{LHHHHLL}（携帯電話）
• [さかな]{LHH}（魚） -> こざかな{LHLL}（小魚）
• [あたま ]{LHHL}（頭） -> いしあたま{LHHLL}（石頭）
• [おとこ ]{LHHL}（男）-> おおおとこ{LHHLL}（大男）
• [エアコン]{LHHH} -> たきのうエアコン{LHHHHLLL}（多機能エアコン）
• [こうえん]{LHHH} -> こくりつこうえん{LHHHHLLL}（国立公園）

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The location of pitch-accent is quite complicated because many factors have something to do with it. Moreover, many words are changing in their pitch-accent. I can hardly explain it perfectly.