Tafadhali usitumie sauti kali unapozungumza na mtoto.

Tafadhali means please. It makes the sentence more polite.

In Swahili, tafadhali can appear at the beginning of a request or command very naturally:

• Tafadhali kaa chini. = Please sit down.
• Tafadhali usiondoke. = Please don’t leave.

So in this sentence, it softens the negative command.

Usitumie is made of several parts:

• u- = you (singular)
• -si- = negative marker
• tumi- = root of kutumia (to use)
• -e = subjunctive ending

So:

u-si-tumi-e = you should not use / don’t use

Swahili often packs subject, negation, tense, and verb into a single word. That is why it is written as one word, not several separate words as in English.

This is because negative commands in Swahili usually use the subjunctive ending -e, not the normal final -a.

Compare:

• Tumia = Use!
• Usitumie = Don’t use!

This is a very common pattern:

• Soma = Read!

• Usisome = Don’t read!

• Fanya = Do!
• Usifanye = Don’t do!

So usitumie is the expected negative command form of kutumia.

It is talking to one person.

The u- in usitumie and unapozungumza shows second person singular (you, one person).

If you were talking to more than one person, you would change it to plural:

• Tafadhali msitumie sauti kali mnapozungumza na mtoto.

Here:

• msi- = don’t you all
• mna- = you all are

Literally, it means something like strong voice, sharp voice, or harsh voice.

• sauti = voice / sound
• kali = sharp, fierce, intense, harsh, strong

In this sentence, sauti kali means a harsh, raised, or stern tone of voice.

This is a good example of how kali has a wider meaning than just one English word. Depending on context, it can mean:

• sharp
• severe
• intense
• strong
• harsh
• loud-ish/forceful

So here it refers to how someone speaks, not just volume alone.

This is because sauti belongs to a noun class where the adjective often stays in a form like kali.

So:

• sauti kali = a harsh/loud voice
• sauti nzuri = a good/nice voice

You do not say mkali here because the adjective agreement does not work that way with sauti.

This is something learners often have to get used to in Swahili: adjective forms depend on the noun class, not just on the meaning.

Unapozungumza means when you are speaking or as you speak.

It can be broken down like this:

• u- = you (singular)
• -na- = present tense
• -po- = a relative marker here giving the sense of when
• zungumza = speak / talk

So the whole form means something like:

when you speak / when you are speaking

In natural English, the sentence is best understood as: Please don’t use a harsh voice when speaking to a child.

Here -po- helps create the meaning when.

So unapozungumza is not just you are speaking; it is more like when you are speaking.

This kind of form is very common in Swahili for time-related clauses:

• ninapokula = when I eat / when I am eating
• anapokuja = when he/she comes
• tunapofika = when we arrive

For many learners, it helps to think of -po- here as part of a built-in when structure.

Yes, very often you could.

• unapozungumza na mtoto = when you speak / when you are speaking to a child
• ukizungumza na mtoto = when speaking / if you speak / while speaking to a child

In many everyday situations, both can work. However, they are not always identical in nuance.

Very roughly:

• unapozungumza is a more explicit when you speak
• ukizungumza can feel a bit more like while speaking or when/if speaking

In this sentence, both would sound natural, but unapozungumza is very clear and standard.

Because kuzungumza na means to speak with / to speak to someone.

So:

• kuzungumza na mtoto = to speak to a child

The preposition na often means with, but in contexts of communication it can also correspond to English to:

• Ninazungumza na mwalimu. = I am speaking to the teacher.
• Aliongea na mama yake. = He/she spoke to his/her mother.

So na mtoto is exactly what you would expect here.

Mtoto is singular: child.
Watoto is plural: children.

So:

• mtoto = one child
• watoto = more than one child

If the sentence were about children in general, you could say:

• Tafadhali usitumie sauti kali unapozungumza na watoto.

That would mean Please don’t use a harsh voice when speaking to children.

It is grammatically a negative command, but because it begins with tafadhali, it sounds like a polite request.

Without tafadhali, it would sound more direct:

• Usitumie sauti kali unapozungumza na mtoto. = Don’t use a harsh voice when speaking to a child.

With tafadhali, it becomes softer and more courteous:

• Tafadhali usitumie sauti kali unapozungumza na mtoto.

So it is still telling someone what not to do, but politely.

Yes, Swahili word order is somewhat flexible, especially with time clauses like this one.

For example, you could also say:

• Tafadhali, unapozungumza na mtoto, usitumie sauti kali.

This still means the same thing: Please, when speaking to a child, don’t use a harsh voice.

The original version is very natural, but moving the when clause is also possible.

It can mean both voice and sound, depending on context.

Examples:

• Ninasikia sauti. = I hear a sound.
• Ana sauti nzuri. = He/she has a nice voice.

In this sentence, because someone is speaking, sauti is best understood as voice or tone of voice, not just any sound.

The dictionary form is kuzungumza, meaning to speak or to talk.

In the sentence, you see it inside unapozungumza.

So:

• kuzungumza = to speak
• unapozungumza = when you speak / when you are speaking

A lot of Swahili verbs work this way: the dictionary form begins with ku-, and then in actual sentences the verb root combines with subject and tense markers.