Place it right after the knock, the doorbell or the incoming message, then follow it with a surprised reaction for the answer. Pair it with the sudden suspense cue before the reveal, or follow it with a confused huh and an oh my god wow when the identity turns out unexpected.
Об этом звуке
This is a very short Spanish voice clip, lasting about a second, in which a speaker asks '¿Quién es?' in a direct, questioning tone. The clipped delivery makes it feel curious and slightly suspicious, as if the speaker has just heard a knock or an unfamiliar voice and wants an answer before opening up. It works best as a quick, playful challenge to an unseen caller.