Hiragana
To write the voiced sounds for “g”, “d”, “z” and “b” two little lines called a dakuten (゛) are added after a character starting with the unvoiced sounds  “k”, “t”, “s” and “h”.  A circle, (゜), is added after a “h” for the sound “p”.  For example: は gives the sound “ha”; ば gives the sound “ba”; ぱ gives the sound “pa”.