pitch accent exception that changes from heiban to atamadaka (学校)

Question

I am using the anki N5 and N4 vocabulary decks based on the 日本語総まとめ　books (edition is ask). As far as I know 学校 is always heiban but in that example:
日本語の学校を見学します。
in the audio to me it sounds like they prounounce it as
にほんごの{LHHHH}がっこうを{HLLLL}けんがくします{LHHHHHL}。
Am I hearing it wrong, or is there a rule, either specific to the word 学校 or one that applies to a category of words that includes it that makes the word's pitch accent change from heiban to atamadaka?

Answer 1

You are both hearing and reading it wrong.

It is not 日本語{にほんご}の学校{がっこう}, it is 日本語{にほんご}学校{がっこう}.

The latter is a compound noun, which causes it to get a compound accent, にほんごが＼っこう. This is how most (but not all) noun compounds behave.

If it was 日本語の学校 it would be just be the juxtaposition of the underlying accents, にほんごの￣・がっこう￣