Your brain sorts speech before you follow it
Hearing a sentence is not a single step. The brain rapidly groups changing sounds into likely speech patterns, then uses familiar words and grammar to work out what was said. Years of listening to a native language make its sound combinations and rhythms easier to categorize, often without conscious effort.
In a place where most conversations use unfamiliar languages, those patterns are less predictable. Your attention can still register the general rise and fall of voices, but it has fewer cues for turning the stream into recognizable words. A familiar phrase, by contrast, can suddenly become intelligible almost as soon as it begins.
Recognition can seize attention
That shift from indistinct speech to meaningful language helps explain the jolt. Once your mind detects a familiar sound pattern, it can start matching it against words and phrases you know. You may orient toward the speaker before deciding to listen, because the speech has become relevant rather than merely part of the surrounding noise.
The effect depends on what you have learned, not simply on where you were born. Someone fluent in another language may notice it just as readily; a regional accent or an unfamiliar speaking style can make even a native language harder to recognize at first. What stands out is the speech your experience has taught your brain to decode quickly.
