Dakuten

Dakuten (濁点?), colloquially ten-ten ("dot dot"), is a diacritic sign most often used in the Japanese kana syllabaries to indicate that the consonant of a syllable should be pronounced voiced. Handakuten (半濁点), colloquially maru ("circle"), is a diacritic used with the kana for syllables starting with h to indicate that they should instead be pronounced with . The kun-yomi pronunciation of the character 濁 is nigori; hence the daku-ten may also be called the nigori-ten. The meaning of this character—muddy or turbid—is a hint that the theory behind this kind of spelling device originally came from China, where consonant sounds were traditionally described by terms such as clear, half-clear, muddy, and so on.