Remove the music and surrounding sound just before the shock to create silence. When the audience leans in to listen, the loud sound bursts out and startles them even more.
The 1–3 seconds before a jump scare, the moment when tension relaxes and it seems like "nothing's going on."
Mute the sound of the generated clip and rebuild it in editing. 2–3 seconds before the shock, remove the music and background sound or lower them to almost zero (afade=t=out, or volume over a set range). Leave only one small sound, like breathing or a clock ticking. Put a loud sound effect on the shock frame. Rather than complete silence, leaving a very quiet room sound (room tone) keeps it from sounding like the audio dropped out by mistake.
Two-shot sequence: Shot 1, a woman closes a creaky cellar door behind her and tiptoes down wooden stairs holding a candle, all sound dropping away to dead silence for the last 1.5 seconds, 4 seconds; hard cut to Shot 2, the candle flame is suddenly blown out and a loud slam echoes in total darkness, 2 seconds.
Cat People (1942) — The quiet of a night walk and the sparse clicks of high heels build tension, and then a bus enters the frame with a loud, jarring sound (Wikipedia — Jump scare)
Insider — How Sound Is Used To Create Suspense In Horror Movies
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