El audiómetro mide el umbral auditivo.

Yes. Audiómetro is a masculine singular noun, so it takes el.

A few helpful points:

• Nouns ending in -o are often masculine in Spanish.
• The article el tells you the gender and number: el audiómetro = masculine singular.
• In the plural, it becomes los audiómetros.

So this sentence starts with a standard noun phrase: el audiómetro.

Because both are being treated as specific or generic definite nouns.

In Spanish, the definite article is used more often than in English. Here:

• El audiómetro can mean the audiometer or an audiometer as a type of device, depending on context.
• El umbral auditivo refers to the hearing threshold as the thing being measured.

So Spanish often says:

• El audiómetro mide el umbral auditivo where English might say:
• An audiometer measures hearing threshold or
• The audiometer measures the hearing threshold

Spanish is more comfortable using el/la/los/las in general statements.

Mide comes from the verb medir, which means to measure.

It is an irregular stem-changing verb in the present tense:

• yo mido
• tú mides
• él/ella/usted mide
• nosotros medimos
• ellos/ellas/ustedes miden

The e in medir changes to i in most present-tense forms. That is why you get mide, not mede.

This is a very common Spanish pattern.

Mide is:

• present tense
• third person singular
• from medir

It agrees with the subject el audiómetro, which is singular.

So the structure is:

• El audiómetro = subject
• mide = verb
• el umbral auditivo = direct object

In other words: The audiometer + measures + the hearing threshold

Because in Spanish, descriptive adjectives usually come after the noun.

So:

• umbral auditivo = auditory threshold / hearing threshold

This is the normal word order for a technical or descriptive phrase. Putting the adjective after the noun sounds natural and standard in Spanish, especially in scientific or medical language.

If you moved it before the noun, it would sound unusual here.

Literally, it means something like auditory threshold.

Breaking it down:

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

So umbral auditivo is the standard technical phrase for the hearing threshold.

This is a good example of how Spanish often uses:

• noun + adjective where English often prefers:
• adjective + noun

The accent mark shows where the stress goes: au-DIÓ-me-tro.

Without getting too technical, audiómetro is stressed on the third-to-last syllable, and Spanish spelling rules require a written accent in words of that type.

So the accent mark is not optional. It tells you the correct pronunciation and is part of the correct spelling:

• audiómetro ✅
• audiometro ❌

A simple pronunciation guide for a Latin American learner context could be:

el aw-DYOH-meh-tro MEE-deh el oom-BRAHL aw-dee-TEE-bo

A few notes:

• audiómetro has the stress on dió
• mide sounds like MEE-deh
• umbral has the stress on the last syllable: oom-BRAHL
• auditivo has the stress on ti: aw-dee-TEE-bo
• The r in umbral is a light Spanish r
• The d between vowels can sound softer than English d

You could, but it changes the nuance.

• El audiómetro mide el umbral auditivo = a general fact, definition, or normal function
• El audiómetro está midiendo el umbral auditivo = the audiometer is measuring the hearing threshold right now

So the original sentence is better if you are describing what the device does in general.

Yes. Auditivo agrees with umbral in gender and number.

Since umbral is:

• masculine
• singular

the adjective is also:

• masculine singular → auditivo

If the noun changed, the adjective would change too. For example:

• los umbrales auditivos = masculine plural

This agreement is a basic rule in Spanish: adjectives usually match the nouns they describe.

Not especially in casual conversation. It is a real and correct word, but it often sounds a bit technical, formal, or specialized depending on context.

In medical or scientific language, though, it is very normal:

• umbral del dolor = pain threshold
• umbral auditivo = hearing threshold

So in this sentence, umbral fits the technical register very well.