pitch accent - Pronunciation Troubles with トラブル and トラブる: Loanwords with both noun and verb ending in ru mora

Following this comment:

What is the difference in pronunciation or pitch accent between:

• トラブル and トラブる


• ダブル and ダブる

What are the regional differences (if any)?

Is the pronunciation rule generalisable to other pairs of the form ＊＊ル and ＊＊る?

Answer

[トラブル]{LHLL} -- [トラブる]{LHHL}

[ダブル]{HLL} -- [ダブる]{LHL}

[バトル]{HLL} -- [バトる]{LHL}?

(I can't think of any other pairs...)

The verbs seem to have a pronunciation rule:

[サボる]{LHL}、 [テンパる]{LHHL}、 [ハモる]{LHL}、 [パニクる]{LHHL}、 [バグる]{LHL}、 [ググる]{LHL}、 [スタンバる]{LHHHL} ...

But I can't find a rule for loanwords ending with ル...

[トラブル]{LHLL}、 [サンダル]{LHHH}、 [ライフル]{HLLL}、 [バトル]{HLL}、 [メタル]{LHH} / [メタル]{HLL}、[メダル]{LHH}...

_{As for the regional differences: In Kansai, for example, we pronounce these verbs like: [サボる]{HHH}、[テンパる]{HHHH}、[ハモる]{HHH}、[パニクる]{HHHH}、[バグる]{HHH}...}