For pronunciation and definitions of だくてん – see the following entry.
[noun] a voicing diacritical mark, such as on , used to:
[noun] derive the kana for a voiced-onsetted mora from the kana for a base voiceless-onsetted mora;
[noun] (informal) orthographically convey a guttural tone, such as that of a cry or scream
(This term, だくてん (dakuten), is the hiragana spelling of the above term.)