The following presentation was created for FLT841 - Sociolinguistics and Spoken Language. This covers several different tones of voice used in Japanese, including "sweet voice" (professional sounding voices, often used in anime); "yakuwarigo" (specific role language - how someone should sound, depending on age and status), and male-vs.-female variations of the word "I".
Adachi, C. (2016). Sugoi! – Indexicality and stance taking in Japanese compliments. Language in Society, 45, 193-216. doi:10.1017/S0047404515000974
Itakura, H. (2015). Constructing Japanese men's multidimensional identities: a case study of mixed-gender talk. Pragmatics, 25(2), 1-79-203. doi:10.1075/prag.25.2.03ita
Starr, R. L. (2015). Sweet Voice: the role of voice quality in a Japanese feminine style. Language in Society, 44, 1-34. doi:10.1017/S0047404514000724
Teshigawara, M., & Kinsui, S. (2011). Modern Japanese 'role language' (yakuwarigo): Fictionalised orality in Japanese literature and popular culture. Sociolinguistic Studies, 5(1), 37-58. doi:http://dx.doi.org.proxy2.cl.msu.edu/10.1558/sols.v5i1.37