Task: Question Generation
Input (English): 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 ⟨◌ʱ⟩ for the breathy-voiced release of obstruents.
Output (English): What do some linguists restrict the double-dot subscript ⟨◌̤⟩ to?