Burmese has four tones. Each tonal contrasts involve not only differences in pitch and vowel length but also differences in voice quality (clear, breathy or creaky). The presence or absence of a glottal stop at the end of a syllable is considered to be part of the tonal system.
And consonants are divided into four classes [low (long, low, clear voice), high (long, high, sometimes breathy voice), creaky (short, high, creaky voice), checked (very short, mid-high, clear voice with final glottal stop)]