الدليل الصوتي عند مدخل المتحف.

Because Arabic usually omits the present-tense verb to be.

So الدليل الصوتي عند مدخل المتحف literally looks like:

• the audio guide
• at the entrance of the museum

But it means The audio guide is at the museum entrance.

This is a very common Arabic pattern called a nominal sentence. In the present tense, Arabic normally does not say is / are / am.

If you wanted a past-tense version, then Arabic would use a verb, for example:

• كان الدليل الصوتي عند مدخل المتحف = The audio guide was at the museum entrance

It is a noun + adjective phrase:

• الدليل = the guide
• الصوتي = audio / sound-related

So literally it is the audio guide or the sound guide.

A useful note: صوتي can mean different things depending on context:

• audio
• acoustic
• phonetic

Here, because it is describing دليل, the natural meaning is audio guide.

Because الصوتي is an adjective describing الدليل, and Arabic adjectives agree with the nouns they describe.

That means the adjective usually matches the noun in:

• definiteness
• gender
• number
• case

Here:

• الدليل = definite (the guide)
• so the adjective must also be definite
• therefore: الصوتي = the audio

So Arabic says:

• الدليل الصوتي

not:

• الدليل صوتي

If you made the noun indefinite, the adjective would also become indefinite:

• دليل صوتي = an audio guide

Because ص is a sun letter.

In Arabic, the ل of الـ is pronounced clearly before some letters, but it assimilates before others. ص is one of the letters that causes assimilation.

So although it is written:

• الصوتي

it is pronounced:

• aṣ-ṣawtī

By contrast, in المتحف, the first letter after الـ is م, which is a moon letter, so the l sound is pronounced:

• al-matḥaf

So in this sentence you get both patterns:

• الدليل = ad-dalīl? Wait—actually د is also a sun letter, so this is pronounced ad-dalīl
• الصوتي = aṣ-ṣawtī
• المتحف = al-matḥaf

Here عند means something like:

• at
• by
• near

In this sentence, the most natural translation is at:

• at the museum entrance

عند is very common in Arabic and often expresses location. It can also have other meanings in other contexts, such as with or in someone’s possession, for example:

• عندي كتاب = I have a book / literally A book is with me

So its exact English translation depends on context.

Because this is an iḍāfa construction, often called a construct phrase.

مدخل المتحف means:

• the entrance of the museum
• more naturally in English: the museum entrance

In an iḍāfa:

• the first noun does not normally take الـ
• the second noun can be definite or indefinite
• the whole phrase gets its definiteness from the second noun

So:

• مدخل متحف = a museum entrance
• مدخل المتحف = the museum entrance

That is why Arabic says:

• مدخل المتحف

not:

• المدخل المتحف

Because it is the second part of an iḍāfa phrase:

• مدخل المتحف = entrance of the museum

In Arabic, the second noun in an iḍāfa is put in the genitive case.

So, in fully vowelled Arabic, you would have:

• المتحفِ

with a kasra at the end.

Also, in this sentence, مدخل itself is linked to عند, and that also leads into a genitive relationship:

• عندَ مدخلِ المتحفِ

So both مدخلِ and المتحفِ appear in genitive form in full formal pronunciation.

This is one of the key features of iḍāfa.

Even when the whole phrase is definite, the first noun usually does not take الـ.

So:

• مدخل المتحف is definite as a whole
• but only the second noun shows that definiteness directly with الـ

Think of it this way:

• مدخل by itself = entrance
• المتحف = the museum
• together, مدخل المتحف = the entrance of the museum / the museum entrance

So the definiteness of the whole phrase comes from المتحف, not from putting الـ on مدخل.

In fully vowelled, careful MSA, the sentence would be:

• الدَّلِيلُ الصَّوْتِيُّ عِندَ مَدْخَلِ الْمَتْحَفِ

The case endings are:

• الدليلُ = nominative, because it is the subject/topic of the nominal sentence
• الصوتيُّ = nominative, because it is an adjective matching الدليل
• عندَ = usually treated as an adverbial expression with fatḥa
• مدخلِ = genitive after عند
• المتحفِ = genitive as the second term of the iḍāfa

In normal speech, many speakers do not pronounce these endings fully, especially at the ends of phrases, but they matter in formal grammar.

Yes, Arabic word order is somewhat flexible, but the version you have is the most straightforward and neutral for this meaning:

• الدليل الصوتي عند مدخل المتحف

This starts with the thing being talked about, then gives its location.

You may also see location expressions placed earlier for emphasis or style, but that is less neutral. For example:

• عند مدخل المتحف يوجد الدليل الصوتي
• الدليل الصوتي موجود عند مدخل المتحف

These are also natural, but they slightly change the feel:

• يوجد adds an explicit there is
• موجود adds an explicit located/present

The original sentence is short, natural, and very typical Arabic.

No. دليل can mean different things depending on context, including:

• guide
• proof
• evidence
• indicator

That can be confusing for learners.

For example:

• دليل سياحي = tour guide
• دليل استخدام = user guide / manual
• هذا دليل على... = This is evidence of...

In your sentence, because it is followed by الصوتي, the meaning is clearly audio guide.

They are related, but not the same.

• مدخل = entrance / entryway
• باب = door / gate

So:

• مدخل المتحف = the museum entrance
• باب المتحف = the museum door or gate

In many contexts they may refer to nearby physical areas, but مدخل is broader. It focuses on the place where you enter, not just the door itself.

That is why مدخل is a very natural choice here.