Pitch accent of months?

Question

I'm having some trouble identifying a pattern/rule in the pitch accent for months.

For example, the 4-mora, 2-kanji 三月 is HLLL (頭高) while 六月、七月、八月、十月 are LHHH (平板/尾高). (As is usually the case.)

For 二月, OJAD states it is HLL (頭高) while NHK states it is LHH (平板/尾高). My native speaker girlfriend says that both are fine, but she also says 四月 as HLL (頭高), while both dictionaries claim it is LHH.

Are the pronunciations of these words just super flexible? If so, is there some simple rule of thumb I can follow?

Answer 1

二月　HLL(me)　　LHH(NHK)
二月四日　HLL(me) ≧ LHH(me)

四月　HLL(me)　　LHH(NHK)
四月四日　HLL(me)　≧ LHH(me)

I'm a native and I live in Yokohama since about 50 years ago.

I noticed two things:

1. The names of the two months concerned have only one syllable. Confusion may likely occur between them when spoken with a small voice or low pitch at the biginning like LHH. Therefore, we seem to become to speak them naturally with loud voice or with high pitch at the beginning of them like in HLL even both pronunciations are allowed.

2. The pitch is different when saying only the name of the month and when saying the month and the date together.
   Even in the latter case, I think that the previous noticing is involved. For example, when 二月四日 is pronounced, 二月 is usually known in the conversation, so what you only have to listen to clearly is 四日. Therefore, 二月 may be allowed to be pronounced lightly. So if two pronunciations are allowed, 二月 may be pronounced in LHH pitches, which is sometimes hard to listen to.

By the way, although 四月 is claimed to be pronounced as LHH in both dictionaries, I think that this is a phonologist's preferred expression, and I usually pronounce the word expressed by this mark flatly without placing an accent anywhere with my intention like LLL not like HHH.

---

Bonus

In my answer I wrote that in order to clearly convey one-syllable words, we devise to pronounce them in a loud voice or we put a pitch accent on the starting point of the word like HLL, even it is claimed to be pronouced in LHH or flatly.

I think that this device is applied to the Japanese who speak with standard pronunciation and accent including myself, but I would like to introduce different measures that the Kansai dialect takes so that one-syllable words could be heard more clearly.

When the Kansai people pronounce a one-syllable word like "[木]{ki} tree", "[酢]{su} vinegar" or "[手]{te} hand", instead of placing an high pitch accent at the begininng of it, they would enlong the vowel and add the same vowel after the enlonged one like 酢 suh-u.

The way to pronounce it is to lower the pitch gradually from the begining of the word to the enlonged vowel and to raise the pitch suddenly at the lastly added vowel. In this way, they pronouce a one-syllable word as much as two to three times long.

By doing this, enough time could be secured for listeners to hear the pronounced one-syllable word. I think the Kansai people are clever.

I do not know why, but regarding the pronunciation of 二月 and 四月, I think that the Kansai dialect does not use its good device.

Answer 2

You can try FORVO for checking the pronounciation https://forvo.com/word/%E4%BA%8C%E6%9C%88/#ja

Three of four speakers pronounce 二月 as LHH, and one (from the US) pronounces it as HLL.　

As a rule of thumb 月 (gatsu) and 日 (nichi) are 尾高 when they follow accented number, and 頭高 when they follow nonaccented number (3,5,9) (9 is considered nonaccented only as く, when it's きゅう it's considered accented).