Pitch: Why for mom and dad is the 2nd syllable stressed but for aunt and uncle is the 1st syllable stressed?


I notice in [the pitch /
stress](https://japanese.stackexchange.com/questions/24690/idina-menzel-
pronounces-sayaka-%E6%B2%99%E4%B9%9F%E5%8A%A0) or whatever it's oKAA-san and
oTOU-san but then it's Oba-san and Oji-san. Why?

I'm not so familiar with this LH HL thing but I think it's:

お母【LH】, お父【LH】

おじ【HL】, おば【HL】




> it's oKAA-san and oTOU-san but then it's Oba-san and Oji-san.

> お母【LH】, お父【LH】
>
> おじ【HL】, おば【HL】

I think these are incorrect, I'm afraid. In Standard Japanese:

> [おかあさん]{LHLLL} [おとうさん]{LHLLL} [おばさん]{LHHH} [おじさん]{LHHH}  
>  i.e. oKAa-san, oTOu-san, oBA-SAN, oJI-SAN

> [おかあ]{LHL} [おとう]{LHL}*
>
> [おじ]{LH} [おば]{LH}

*おかあさん, おとうさん, おねえさん, おばあさん etc. are お+かあさん, お+とうさん, お+ねえさん, お+ばあさん (prefix お is attached to かあさん etc.), rather than おかあ+さん, おとう+さん, おねえ+さん, おばあ+さん (suffix さん is attached to おかあ, おねえ etc.)

* * *

By the way, (as you may know,) the pitch of the suffix ～さん depends on the
pitch of the final sound (or mora?) of the preceding word:

> [さとう]{HLL} + さん → [さとうさん]{HLLLL}  
>  [たかはし]{LHLL} + さん → [たかはしさん]{LHLLLL}  
>  [ひろこ]{HLL} + さん → [ひろこさん]{HLLLL}

and

> [すずき]{LHH} + さん → [すずきさん]{LHHHH}  
>  [やまもと]{LHHH} + さん → [やまもとさん]{LHHHHH}  
>  [ひろみ]{LHH} + さん → [ひろみさん]{LHHHH}

In the same way...

(お) + [かあ]{HL} + さん → ([お]{L})[かあさん]{HLLL}  
[おば]{LH} + さん → [おばさん]{LHHH}

* * *

In reply to DJ's comment:

The pitch of [おばさん]{LHHH} and [おじさん]{LHHH} change to [おばさん]{HLLL} and
[おじさん]{HLLL} when they're attached to a name:

[ひろこ]{HLL} + [おばさん]{LHHH} → [ひろこおばさん]{LHHHLLL}  
[たろう]{HLL} + [おじさん]{LHHH} → [たろうおじさん]{LHHHLLL}

