Intonasjonen blir bedre.

Because Norwegian usually puts the definite article at the end of the noun instead of using a separate word like the.

• intonasjon = intonation
• intonasjonen = the intonation

So -en here is the definite ending for a singular noun of this type.

The base form is intonasjon.

This is the dictionary form, also called the indefinite singular form.

A quick pattern:

• en intonasjon = an intonation
• intonasjonen = the intonation

Blir is the present tense of bli, which often means become or get.

So in this sentence:

• blir bedre = gets better / becomes better

That is why the sentence expresses a change, not just a fixed state.

This is an important difference.

• Intonasjonen blir bedre = The intonation is getting better / becoming better
• Intonasjonen er bedre = The intonation is better

So:

• blir focuses on improvement or change
• er describes a state

If someone’s pronunciation is improving over time, blir bedre is very natural.

Bedre means better. It is the comparative form.

Common forms are:

• god / bra = good
• bedre = better
• best = best

In this sentence, bedre means the intonation is improving compared with how it was before.

Because Norwegian often marks definiteness with an ending on the noun instead.

English:

• the intonation

Norwegian:

• intonasjonen

So the meaning of the is already included in intonasjonen.

This sentence has the normal basic word order:

• Intonasjonen = subject
• blir = verb
• bedre = complement

So it follows the common Norwegian pattern:

Subject + verb + complement

That makes it very straightforward.

A rough English-friendly guide would be:

in-to-na-SHO-nen blir BED-re

A few notes:

• sj in -sjonen sounds like sh
• blir has a long i sound
• bedre has two syllables: BED-re
• The r sound may vary depending on dialect

A more natural learner-friendly approximation is:

in-to-na-SHO-nen blir BED-re

This sentence is standard Bokmål.

In Nynorsk, you would more often see:

Intonasjonen blir betre.

The main difference here is:

• Bokmål: bedre
• Nynorsk: betre

Yes, possibly, depending on context.

• intonasjon is a more technical or linguistic word: intonation
• tonefall is a more everyday word: tone of voice / intonation pattern

So Intonasjonen blir bedre sounds perfectly natural, especially in language learning or pronunciation contexts.
Tonefallet blir bedre can also work, but it may feel a bit different in nuance.

You can change blir to the past tense ble:

• Intonasjonen ble bedre. = The intonation got better / became better.

You could also say:

• Intonasjonen har blitt bedre. = The intonation has gotten better / has become better.

So:

• blir = present
• ble = past
• har blitt = present perfect

No, bedre stays the same.

That is one nice thing about comparatives in Norwegian: they usually do not change for gender or number.

Examples:

• Uttalen blir bedre. = The pronunciation gets better.
• Setningene blir bedre. = The sentences get better.
• Resultatet blir bedre. = The result gets better.

In all of these, bedre stays bedre.