Read this: Some linguists restrict the double-dot subscript to murmured sonorants, such as vowels and nasals, which are murmured throughout their duration, and use the superscript hook-aitch for the breathy-voiced release of obstruents.
Now answer this question, if there is an answer (If it cannot be answered, return "unanswerable"): What is used for the loud-voiced release of obstruents?
unanswerable