Learn Hardcore Finnish: Pidä puhelin äänettömällä, ettet häiritse kokousta. - Keep your phone on silent so that you don’t disturb the meeting.

Pidä is the 2nd person singular imperative of pitää (to keep / hold / maintain).
So Pidä puhelin äänettömällä means Keep the phone on silent.

The verb pitää has an irregular imperative stem:

infinitive: pitää
imperative (sinä): pidä (not pitä)

Why is puhelin (not puhelimen) used as the object?

In Finnish, with an imperative, a total object is often in the nominative singular:

Sulje ovi. = Close the door.
Ota kirja. = Take the book.
Pidä puhelin äänettömällä. = Keep the phone on silent.

In a normal statement you’d typically see the -n form:

Pidän puhelimen äänettömällä. = I keep the phone on silent.

Does this mean my phone, or a phone, or your phone?

By default, puhelin here is understood as your phone from context (because it’s an instruction to you), but Finnish often doesn’t mark possession unless it matters.

If you want to make it explicit, you can say:

Pidä puhelimesi äänettömällä. = Keep your phone on silent.

What case is äänettömällä, and why is it in that case?

Äänettömällä is the adessive case (-lla/-llä) of äänetön (silent).

Here it expresses being in/at a setting or mode (roughly: on silent). Finnish commonly uses adessive for “on a setting/state”:

Puhelin on äänettömällä. = The phone is on silent.
Pidä puhelin äänettömällä. = Keep the phone on silent.

It’s like an implied phrase äänettömällä (tilalla) = in silent mode.

Could I also say äänettömälle instead of äänettömällä?

Yes, but it changes the nuance:

Pidä puhelin äänettömällä = keep it in that state (maintain silent mode)
Laita puhelin äänettömälle / Pane puhelin äänettömälle = put/set it to silent mode (movement into the state)

So -llä is “already there / staying there”, and -lle often matches “set it into that mode.”

What does ettet mean, and how is it built?

Ettet is essentially että + et in a purpose/avoidance clause:

että = that / so that
et = you do not

So ettet häiritse kokousta = so that you don’t disturb the meeting.

It agrees with sinä (you). If the subject were different, it would change:

…ettei hän häiritse… = so that he/she doesn’t disturb…
…etten häiritse… = so that I don’t disturb…

Why is it häiritse, not häiritset?

Because Finnish forms negation with a separate negative auxiliary (here inside ettet = et) and the main verb goes into a special form called the connegative.

So you get:

affirmative: (sinä) häiritset = you disturb
negative: (sinä) et häiritse = you do not disturb

Inside the clause it’s the same pattern, just fused into ettet:

ettet häiritse = so that you don’t disturb

Why is kokousta in the partitive case?

Häiritä very often takes a partitive object, especially when the idea is disturbing an ongoing situation/process rather than affecting something as a completed whole:

häiritä kokousta = disturb the meeting (while it’s going on)

You might see kokouksen in some contexts, but kokousta is the most natural and common here.

Is ett(et) the only way to say “so that you don’t …”? What are alternatives?

Common alternatives include:

jotta et häiritse kokousta = so that you don’t disturb the meeting
ettei kokous häiriinny = so that the meeting isn’t disturbed (different structure)

ett(et) is very common in instructions and warnings, especially in writing.

Can the word order be changed? Why is it this order?

The basic, neutral order is:

Pidä + object + state: Pidä puhelin äänettömällä.

You can reorder for emphasis, but it starts to feel marked:

Pidä äänettömällä puhelin sounds unusual unless you’re contrasting (e.g., not on vibrate).

The second clause is also quite neutral:

ettet häiritse kokousta follows naturally as the reason/purpose.

How would I say this to a group, or more politely?

To a group (2nd person plural imperative):

Pitäkää puhelimet äänettömällä, ettette häiritse kokousta.

Softer / more polite options:

Pidäthän puhelimen äänettömällä… (adds a gentle, “please do” tone)
Voisitko pitää puhelimen äänettömällä… = Could you keep your phone on silent…