Underpulse

He did nothing, as yet, which was really the reverse ; he did not make her his evident object, —it seems to me that this is always a high and delicate test of gentlemanhood, — and yet, to me, who felt an underpulse in all these things, there was a plain perception, that as it had been she from whom he went away, it was to her now that he was come back.

Source: wiktionary

He began lightly, but her unforeseen surrender gave to the next words an underpulse of feeling that quite spoiled his response as comedy.

Source: wiktionary

What was missing from the experience, though, was the driving, knife-sharp underpulse of fear.

Source: wiktionary

The music seems to have no particular sense of beginning or end: it doesn't drive toward a cadence; it simply elaborates the big waves with little waves, underpulses, in the way that the surge of surf on a beach falls into long rhythms of tide and medium rhythms of regular wave fall and short rhythms of little splashes at the end of the regular wave fall.

Source: wiktionary