Learn Danish: Børnene var lige ved at sove da en hvisken begyndte. - The children were just about to sleep when a whispering began.

hvisken is a verbal noun meaning "a whispering" or simply "whispering". It is formed by adding -en to the root of the verb at hviske (to whisper). Like almost all verbal nouns formed this way, it takes the common gender, which is why it uses en here.

What does the phrase lige ved at add to the sentence?

The expression at være lige ved at followed by an infinitive means to be "just about to" or "on the verge of" doing something. In this sentence, var lige ved at sove emphasizes that the children were right on the brink of falling asleep.

Why does this sentence use da for "when" instead of når?

This is the classic past-tense rule for "when". Because this sentence describes a single, specific event that happened in the past, Danish requires da. You would only use når in the past tense if it meant "whenever" for a repeated action.

Could we use a regular noun for a whisper instead of the verbal noun en hvisken?

There is actually no standalone noun like "en hvisk" in Danish. To talk about the act of whispering or a whispering sound, Danish relies completely on the verbal noun en hvisken. This makes verbal nouns ending in -en incredibly useful when a direct noun equivalent does not exist.