tosyokan de ha ookina koe de hanasanaide kudasai

で marks the place where an action happens, so 図書館で means in the library.

Adding は after で makes では, which adds a topic or contrast nuance. So 図書館では feels like:

• in the library, ...
• as for in the library, ...
• when it comes to the library, ...

In a sentence like this, では often sounds natural because it sets the location as the context for a rule or instruction.

So:

• 図書館で話さないでください = Please don’t talk in the library.
• 図書館では話さないでください = In the library, please don’t talk. / As for the library, please don’t talk there.

The difference is small, but では is very common in signs, rules, and general statements.

The two で particles do different jobs.

• 図書館では: で marks the place of the action.
• 大きな声で: で marks the means or manner, meaning with or in a loud voice.

So 大きな声で話す literally means to speak with a loud voice.

This use of で is common:

• 日本語で話す = speak in Japanese
• 小さい声で話す = speak in a quiet voice
• 電話で話す = talk by phone

Both 大きな声 and 大きい声 are possible.

• 大きい is an -i adjective
• 大きな is a special form that can only come before a noun

So both of these can mean a loud voice or literally a big voice:

• 大きい声
• 大きな声

In this sentence, 大きな声 is just the chosen phrasing. It is very natural and common.

A useful point:

• 大きい can be used both before a noun and on its own: 声が大きい
• 大きな can only directly modify a noun: 大きな声

You cannot say 声が大きな.

Yes, literally it is big voice, but in natural English we usually say loud voice.

Japanese often uses big/small where English uses loud/quiet:

• 大きい声 / 大きな声 = loud voice
• 小さい声 / 小さな声 = quiet voice

So this is a normal expression, not a strange metaphor.

It is built from the verb 話す (to speak / to talk).

Step by step:

• dictionary form: 話す
• negative plain form: 話さない = do not speak / not speak
• 話さないで = don’t speak / without speaking
• 話さないでください = please do not speak

So 〜ないでください is a very common pattern for polite negative requests:

• 入らないでください = Please do not enter.
• 触らないでください = Please do not touch.
• 写真を撮らないでください = Please do not take photos.

It is a polite request, but in practice it often functions like an instruction or prohibition.

Tone-wise:

• 話すな = very direct, rough: Don’t talk
• 話さないで = softer, casual: Don’t talk
• 話さないでください = polite: Please do not talk

On signs and notices, 〜ないでください is standard and polite, even though it is clearly telling people not to do something.

They are opposites.

• 話してください = Please speak.
• 話さないでください = Please do not speak.

The negative is made with ないでください.

Compare:

• 座ってください = Please sit down.
• 座らないでください = Please do not sit down.

Japanese often leaves out the subject when it is obvious from context.

In a sign or rule, the implied subject is usually you or people in general. So the sentence naturally means:

• Please don’t speak loudly in the library
• People should not speak loudly in the library

Japanese does this all the time. Explicit subjects are much less necessary than in English.

No, normal Japanese is usually written without spaces:

図書館では大きな声で話さないでください。

Spaces are often added in textbooks or beginner materials to make the parts easier to read.

So in real Japanese, you would normally see it written as one continuous sentence.

A natural breakdown is:

• 図書館では = in the library
• 大きな声で = in a loud voice / loudly
• 話さないでください = please do not speak

So the order is basically:

[place] [manner] [verb/request]

Japanese usually puts the verb at the end, which is one of the biggest differences from English.

Yes. In fact, Please don’t talk loudly in the library is the most natural English translation.

Japanese often says things a bit more literally, like with a loud voice, but in English we normally turn that into an adverb:

• 大きな声で話す = speak loudly / talk in a loud voice

So a smooth translation is:

• Please don’t talk loudly in the library.

Either can work in translation.

• 話す can mean to speak
• 話す can also mean to talk

In this sentence, English usually sounds most natural with talk:

• Please don’t talk loudly in the library.

But Please do not speak loudly in the library is also fine.

Not for this meaning.

Here, the library is the place where the action happens, so you need で.

• 図書館で = at/in the library
• 図書館では = in the library, as for that place

に is used for things like destination, existence, or specific points in time, not usually for the location of an action like speaking.

So:

• 図書館で話す = speak in the library
• not 図書館に話す for this meaning

図書館には would mean something different, such as as for the library with に-type functions, but it would not fit this sentence naturally.

It is written with は, but in this pattern it is pronounced wa.

So:

• では is pronounced de wa

This is the same reason why the topic particle は is pronounced wa in general.

So 図書館では sounds like toshokan de wa.