Breakdown of Grannen låter hunden väsnas.
hunden
the dog
grannen
the neighbor
låta
to let, allow
väsnas
to make noise
Questions & Answers about Grannen låter hunden väsnas.
Why isn't there an att before väsnas?
Because låta is used as a causative verb here. When it means to let or allow, it takes an object (hunden) followed directly by a bare infinitive. You drop the att (to) just like in English: lets the dog make noise, not lets the dog to make noise.
Doesn't låter usually mean sounds?
Yes, låta is very commonly used to mean to sound, like in det låter bra (that sounds good). However, when it is followed by an object and another verb, it acts as a causative verb meaning to let or to allow.
Why does väsnas end in an -s? Is it in the passive voice?
No, it is an active action. Väsnas (to make noise) is a deponent verb. These are special verbs that always end in -s but have an active meaning. You have likely seen others at this level, such as hoppas (to hope) and minnas (to remember).
Where does the verb väsnas come from?
It is built from the noun ett väsen, which translates to a noise, a racket, or a commotion. So to väsnas simply means to create a racket.