This might be a bit weird, but when I listen to Japanese music, sometimes I notice "r"-like sounds in syllable-final positions, or between vowels where there should be no [r]. I know that /r/ is not allowed in a syllable-final or word-final position, so I'm trying to figure out what exactly I'm hearing in these songs. If there really is an [r] sound in these positions, why is it legal?
I've tried searching for information on Japanese dialects and allophonic variation, since I thought that's what it would be related to, but I can't find anything that seems related. I mostly find things about language acquisition, like native Japanese speakers learning English, or vice versa, and generally concerning syllable-initial [l/r]. My only guess is that what I hear is nasalisation that I'm interpreting as rhotacisation due to my own dialect, but the vowels I hear rhotacised aren't always connected to nasal consonants or anything, so I'm left wondering why they would be nasalised...
The first example that comes to mind is in the song "Smile Ichiban Ii Onna" by An Cafe, right around 3:28, where I hear a very distinct [r] at the end of 「たいよう」. Immediately followed by 「さ」:
https://www.youtube.com/watch?v=TlO2N2t6MA8&feature=youtu.be&t=3m28s
The other example is from a band called 摩天楼オペラ. The singer's pronunciation is often rhotic to my ears. The first line of this song is 「どれだけの善意が どれだけの悪意が この地上にへばりついてる」, but when he sings 「善意」(ぜんい) it sounds like he's replacing the ん with a schwar or something similar. And when he sings 「悪意」(あくい) I hear an [r] inserted between the く and い. As the song goes on, I continue to hear rhoticisation in various vowels, but not as remarkably...
https://www.youtube.com/watch?v=WxCie8nujj8&feature=youtu.be&t=40s
Sorry if this question isn't as detailed/focused as it should be. It's just something strange I noticed and can't seem to find anything about.
**Possibly relevant information: The other day, I happened upon a pinyin pronunciation chart, and noticed another vowel sound that sounds rhotic, but technically isn't (probably). Obviously, this is a completely different language, but it made me remember my long-time question here. In the first paragraph below the chart itself, it talks about the difference between production of the "sh" and "x" sounds. And while I can't hear the difference between these consonant sounds themselves, they drastically change the following vowel. Specifically, the "x" makes the following vowel sound rhotacised to my ears.... but that's as far as I can get with it. Having my tongue in such a low position (for "x" production) lowers the following vowel production as well, and also seems to prevent my lips from rounding or stretching to the same degree as when producing my normal "sh" sound... But again, I don't notice anything that would cause a similar lowering effect in all of my examples...
I also realised looking back that I didn't include the very first example of this I heard: Miyavi's "Jibun Kakumei." I don't hear it anywhere else in the song except in the word 「言葉」, which sounds like "kerterba" to me. It's softer than the other examples, the [o] sound has become like the German "ö," or [œ] in IPA...