Possible Clues:

• Opening numbers sound tremulous, mostly
• By the sound of it, the whole of it is in 15 across
• Air hole?
• Snort compound, single line - through here?
• Nasal feature
• Sounds as if one knows where to find the whole of it
• It sounds as if one knows about this
• Sounds as if one knows where to find a couple such
• Breathing opening for a human
• Knows the whole of it, by the sound of it