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!