En el supuesto de que cambie el umbral auditivo, actuaremos.

En el supuesto de que means assuming that, in the event that, or on the assumption that.

It is correct Spanish, but it sounds formal and somewhat technical/legal/medical/administrative. In everyday speech, people are more likely to say things like:

• si cambia... = if it changes...
• en caso de que cambie... = in case it changes / if it changes
• suponiendo que cambie... = assuming it changes

So this sentence has a fairly formal register.

Because en el supuesto de que triggers the subjunctive.

After expressions that present something as a possibility, assumption, or hypothetical condition, Spanish normally uses the subjunctive. Here, the change in hearing threshold is not being stated as a fact; it is being presented as something that might happen.

So:

• En el supuesto de que cambie... = correct
• En el supuesto de que cambia... = not correct in standard Spanish

Cambie is the present subjunctive form of cambiar.

Cambiar is an -ar verb. To form the present subjunctive:

1. Start from the yo form of the present indicative: cambio
2. Remove the -o
3. Add subjunctive endings for -ar verbs:
   • yo cambie
   • tú cambies
   • él/ella/usted cambie
   • nosotros/nosotras cambiemos
   • vosotros/vosotras cambiéis
   • ellos/ellas/ustedes cambien

In your sentence, the subject is implied as it/he/she/you formal, so cambie is the right form.

The subject is not stated explicitly, which is very normal in Spanish.

From the context, cambie most naturally refers to el umbral auditivo:

• En el supuesto de que cambie el umbral auditivo... = Assuming the hearing threshold changes...

So the implied subject is el umbral auditivo, which is third person singular, matching cambie.

Spanish allows word order to be more flexible than English.

Both of these are possible:

• ...de que cambie el umbral auditivo
• ...de que el umbral auditivo cambie

The version in your sentence sounds natural, especially in formal or written Spanish. Placing the verb before the subject can make the sentence feel a bit more impersonal or technical.

English usually prefers subject + verb order, but Spanish does not always need that.

Umbral auditivo is a technical term meaning hearing threshold.

• umbral = threshold
• auditivo = auditory / related to hearing

It is commonly used in medical, audiological, or scientific contexts to refer to the lowest level of sound a person can hear.

The comma separates the conditional subordinate clause from the main clause.

• En el supuesto de que cambie el umbral auditivo = subordinate clause
• actuaremos = main clause

This is very normal when a long introductory clause comes first. In English, you would often do the same:

• If the hearing threshold changes, we will act.

The comma helps readability.

Actuaremos is the simple future of actuar and means we will act.

It is used because the action in the main clause is presented as something that will happen after or if the condition is met.

Conjugation of actuar in the future:

• yo actuaré
• tú actuarás
• él/ella/usted actuará
• nosotros/nosotras actuaremos
• vosotros/vosotras actuaréis
• ellos/ellas/ustedes actuarán

In Spanish, this future tense is perfectly natural here, especially in formal writing.

Yes, sometimes Spanish uses the present to refer to the future, especially in speech:

• En el supuesto de que cambie el umbral auditivo, actuamos.

But in this exact sentence, actuaremos sounds more natural because the style is formal and because it clearly marks a future response.

So:

• actuaremos = more explicit, formal, and clear
• actuamos = less likely here, though not impossible in some contexts

Yes, but it would change the tone.

A more everyday version would be:

• Si cambia el umbral auditivo, actuaremos.

That means essentially the same thing: If the hearing threshold changes, we will act.

The difference is mainly register:

• si = neutral, common, everyday
• en el supuesto de que = more formal, more abstract, more bureaucratic/technical

Also note the verb:

• After si for a real possible future condition, Spanish uses the present indicative: si cambia
• After en el supuesto de que, Spanish uses the subjunctive: cambie

Yes. En el supuesto de que is a set expression.

The structure is:

• en el supuesto = in the assumption / under the supposition
• de que = that

So the whole phrase works together as a connector meaning assuming that or in the event that.

You should learn it as one chunk:

• en el supuesto de que + subjunctive

That is more useful than trying to translate each word separately every time.

Literally, supuesto comes from suponer and means something like supposition or assumption in this context.

So en el supuesto de que is literally something like:

• under the assumption that
• in the supposition that

In natural English, though, you would normally translate the whole phrase more smoothly as assuming that or if.

Auditivo means auditory, related to hearing.

It is related in meaning to the idea of hearing, like oír, but it is an adjective used mostly in formal or technical language.

Examples:

• problema auditivo = hearing problem
• memoria auditiva = auditory memory
• umbral auditivo = hearing threshold

Do not confuse it with:

• auditorio = auditorium / audience hall

They look similar but mean different things.

Yes, it strongly sounds that way.

Several things make it feel technical or professional:

• en el supuesto de que is very formal
• umbral auditivo is specialist vocabulary
• actuaremos sounds procedural, like part of a protocol or report

A native speaker would likely expect this sentence in:

• a medical report
• an audiology context
• a clinical protocol
• formal administrative writing

Yes. It is essentially a conditional sentence.

The condition is:

• En el supuesto de que cambie el umbral auditivo = if / assuming the hearing threshold changes

The result is:

• actuaremos = we will act

So even though it does not use si, it functions like an if-clause plus a result clause.

In standard Spanish, the normal and recommended form is:

• en el supuesto de que

Leaving out de would sound nonstandard or incorrect in careful writing. Since this is a fixed formal expression, it is best to memorise it exactly as:

• en el supuesto de que + subjunctive