Answer:

hmm

Answer	Crossword Clue
HMM	"In-teresting..."
HMM	"..., I wonder ..."
HMM	Thoughtful sound

HMM	Perplexed sound
HMM	"Let me think..."
HMM	"Let's see ... "
HMM	"That's an interesting thought ..."
HMM	"Let's see here ..."
HMM	"I'm thinking"
HMM	"Let me think ..."
HMM	"I wonder ..."

HMM	Muse emanation?
HMM	"I'm thinking ..."
HMM	"Let me think about that"
HMM	"That's odd ..."
HMM	"Let me think ... "
HMM	"I'm thinking..."
HMM	"Very interesting..."
HMM	Thoughtful utterance

HMM	"I wonder..."
HMM	"Lemme see ..."
HMM	"Wait, it'll come to me ..."
HMM	"Well, let me see ..."
HMM	Thoughtful interjection
HMM	"Let me see ..."
HMM	"Very interesting ..."
HMM	Start of a response to a brainteaser

HMM	Muser's mumbling
HMM	"Let me think . . ."
HMM	Sound of deep thought
HMM	"Very interesting . . ."
HMM	"Let me see . . ."
HMM	Muser's sound
HMM	"Let me think about it"
HMM	Sound of wheels turning?

HMM	"Interesting ..."
HMM	"Let me consider that ..."
HMM	A musing sound
HMM	"Well, let me think ..."
HMM	"That's curious ..."