Learn Hardcore Indonesian: Psikolog kampus mempelajari pengaruh musik pada stres murid secara mendalam. - The campus psychologist studies the effect of music on students' stress in depth.

In Indonesian, when you have two nouns together and one modifies the other (like campus psychologist, chicken soup, car door), the main noun comes first and the modifier comes after it.
So:

psikolog kampus = campus psychologist (psychologist of the campus)
dokter hewan = animal doctor (veterinarian)
pintu mobil = car door

Putting it as kampus psikolog would sound wrong and confusing, as if kampus were being described by psikolog.

Does psikolog kampus mean “a psychologist who works at a campus” or “a psychologist of the campus (employed by it)”?

Normally psikolog kampus suggests a psychologist who is part of the campus organization, e.g. the campus counselor or mental health professional on staff.
If you just want to say “a psychologist who happens to be at the campus” (location only, not staff), you’d more naturally say psikolog di kampus.

So:

psikolog kampus → campus psychologist (institutionally linked)
psikolog di kampus → a psychologist at/on the campus (physically there)

What is the difference between mempelajari and belajar?

Both relate to “studying/learning,” but they’re used differently:

belajar = to study/learn (intransitive, no direct object needed)
- Saya belajar. = I study / I am studying.
- Saya belajar bahasa Indonesia. = I learn Indonesian.
mempelajari = to study something in depth / examine / analyze (transitive, usually more serious or systematic)
- Psikolog mempelajari pengaruh musik. = The psychologist studies the effect of music.

Using mempelajari here emphasizes that the psychologist is examining it carefully, not just casually learning.

Could I use meneliti instead of mempelajari?

Yes, but the nuance changes slightly:

mempelajari → to study something (can be theoretical or broad, not necessarily a formal research project)
meneliti → to research / investigate (stronger nuance of scientific or systematic research)

So:

Psikolog kampus mempelajari pengaruh musik... = The campus psychologist studies/examines the influence of music...
Psikolog kampus meneliti pengaruh musik... = The campus psychologist conducts research into the influence of music...

Both are grammatically correct; meneliti sounds more like formal research.

How is mempelajari formed? What is its base word?

The base idea comes from ajar (to teach/learn):

ajar → base/root
belajar → to study/learn (intransitive)
pelajar → student
mempelajari → to study something (carefully, in detail)

Morphologically, mempelajari is meN- + pelajar + -i (with sound changes giving mem-).
You don’t need to analyze this every time, but recognizing the pattern helps you see the family: ajar → belajar → pelajar → mempelajari.

What does pengaruh mean exactly, and why is it pengaruh musik?

pengaruh means influence, effect, impact.
pengaruh musik is literally the influence (effect) of music.

In Indonesian, you often just put the two nouns together:

pengaruh musik = the effect of music
pengaruh cuaca = the effect of the weather

You don’t need a word like “of” (though you can add dari: pengaruh dari musik, which is also correct but a bit longer/more explicit).

Why is the preposition pada used in pengaruh musik pada stres murid? Can I use terhadap or untuk?

pada here means on / toward / with respect to and is very common after pengaruh to introduce the thing being affected:

pengaruh musik pada stres murid = the influence of music on students’ stress

You could also say:

pengaruh musik terhadap stres murid – also correct; terhadap sounds a bit more formal/academic.

Using untuk would be odd in this context; untuk usually means for (purpose/benefit), not “on” in the sense of “effect on something”.

Is stres murid singular or plural? Does it mean “a student’s stress” or “students’ stress”?

Indonesian generally doesn’t mark singular/plural on nouns.
murid can mean student or students, depending on context.

So stres murid can mean:

the stress of a (generic) student, or
students’ stress in general.

If you want to make it clearly plural, you can say stres para murid (“the students’ stress”) or stres murid-murid (reduplication to show plural).

What is the structure of stres murid? Why is the order like that?

The structure is the same as psikolog kampus:

main noun: stres (stress)
modifier noun: murid (student[s])

stres murid literally = the stress of (the) student(s) → students’ stress.
In Indonesian, possessor or classifier comes after the main noun:

buku murid = student’s book / students’ book
rumah guru = teacher’s house

So stres murid is “student stress” in English.

Why is stres spelled that way, not stress like in English?

stres is a loanword from English “stress”, adapted to Indonesian spelling.
Indonesian often simplifies consonant clusters and spelling to fit its phonetic system:

stress → stres
class → kelas
traffic → trafik (less common; often still traffic informally)

In standard Indonesian, stres is the correct spelling.

How does secara mendalam work grammatically? Why do we need secara?

secara is used to turn adjectives or nouns into adverb-like phrases, often translated as “in a … way” or “-ly” in English.

mendalam = deep (adjective)
secara mendalam = in a deep way → deeply / in depth

Other examples:

pelan = slow → secara pelan = slowly
resmi = official → secara resmi = officially

So mempelajari ... secara mendalam = to study ... in depth.

Can I replace secara mendalam with something else, or change its position?

Yes. Alternatives:

dengan mendalam – also “deeply / in depth”
mendalam alone sometimes works as an adverb in context, especially in informal speech.

Position-wise, Indonesian often places such an adverbial phrase at the end of the sentence, as in the example.
You could move it earlier (e.g. Psikolog kampus secara mendalam mempelajari...), but the original [verb + object + secara mendalam] is very natural and common.

Why is there no word for “the” or “a” in Psikolog kampus mempelajari ...? How do I know if it’s definite or indefinite?

Indonesian doesn’t have articles like “a/an/the.”
Definiteness (specific vs nonspecific) is understood from context or added words.

Psikolog kampus mempelajari... could be:

The campus psychologist studied...
A campus psychologist studied...

If you really need to emphasize:

Seorang psikolog kampus = a (single) campus psychologist
Psikolog kampus itu = that/the (specific) campus psychologist

But in most cases, context is enough.

Is murid the right word in a campus context? What about mahasiswa?

Both are correct Indonesian words, but they differ in typical usage:

murid usually refers to school students (elementary, junior high, high school).
mahasiswa refers specifically to university/college students.

Since kampus suggests a university/college, many speakers would say:

stres mahasiswa = university students’ stress.

However, murid is still understandable and not grammatically wrong; it just sounds more like younger students unless context is clearly “campus / university.”