La conducción aérea usa un tono puro.

Conducción can mean different things depending on context.

• In everyday Spanish, it can mean driving.
• In technical or medical contexts, it often means conduction.

So in la conducción aérea, it does not mean driving through the air. It means air conduction, which is a technical term.

Spanish often uses the definite article with general concepts, processes, and technical categories.

So la conducción aérea means something like:

• air conduction as a concept
• the air-conduction method/process

English often drops the article where Spanish keeps it. So even if English says just air conduction, Spanish commonly says la conducción aérea.

Because aérea is an adjective describing conducción, and adjectives must agree with the noun in gender and number.

• conducción is feminine singular
• so the adjective must also be feminine singular: aérea

Compare:

• el transporte aéreo
• la conducción aérea

Same adjective, different ending because the noun changes gender.

In Spanish, adjectives usually come after the noun.

So:

• conducción aérea = air conduction

That is the normal order. English often puts the describing word first, but Spanish usually puts it after.

Because it is pronounced in separate syllables: a-é-re-a.

The stress falls on é, and the word is stressed earlier than the second-to-last syllable, so it needs a written accent.

This is also helpful because it shows that a and e are pronounced separately, not blended into one syllable.

Usa is the third-person singular present indicative of usar.

So it means:

• uses / is using / does use, depending on context

The subject is la conducción aérea, which is singular, so the verb is singular too:

• La conducción aérea usa...

Because usar is a transitive verb. It takes a direct object directly.

So:

• usa un tono puro

is correct, because un tono puro is the thing being used.

You do not need a preposition like de or con after usar in this structure.

Un means a or one, so it introduces something non-specific or one item of that type.

• usa un tono puro = it uses a pure tone

If you said el tono puro, that would usually refer to a specific pure tone already known from the context.

Also, tono is a masculine singular noun, so the article is un.

Again, this is the normal position for adjectives in Spanish.

• tono puro = pure tone

Also, in technical language, tono puro is a set phrase. It works like a classification: a tone of the pure type.

If you changed the order to puro tono, it would sound unusual and would not be the normal technical expression.

A simple pronunciation guide is:

la kon-doo-SYON AH-eh-reh-ah OO-sah oon TOH-noh POO-roh

A few notes:

• conducción: stress on the last syllable, -ción
• c before i is pronounced like s in most of Latin America
• aérea: pronounce the vowels separately, a-é-re-a
• usa: stress on u
• tono: stress on to
• puro: stress on pu

Yes, it is grammatically correct and understandable, especially in a technical context.

That said, in real technical Spanish, a speaker might also say something like:

• En la conducción aérea se usa un tono puro.
• La prueba de conducción aérea usa un tono puro.

Those versions can sound a little more natural because conducción aérea is a process or method, not literally a person doing the using. But your original sentence is still correct.