Sound (noun): something that you hear; a vibration that travels through air or another medium and is detected by the ear.
Sound (verb): to make a noise; to give a particular impression when heard or perceived — often followed by an adjective.
Sound (adjective): in good, solid, or healthy condition; thorough and reliable; undisturbed (used of sleep).
What Does Sound Mean?
The word sound is one of the most common and flexible words in English, functioning as a noun, verb, and adjective — each with a distinct meaning and set of collocations. Understanding all three uses will dramatically improve the naturalness of your English.
As a noun, sound refers to any audible vibration: the sound of traffic, the sound of music, a strange sound in the night. It covers everything from the softest whisper to a thunderclap. In phonetics and language teaching, sound also refers to individual speech sounds — the building blocks of pronunciation.
As a verb, sound has two main senses. The first is literal: to produce or emit a noise ('the fire alarm sounded'). The second — and very important for learners — is as a linking verb meaning 'to seem' or 'to give the impression of': 'That sounds like a great idea.' In this second sense it behaves like look, feel, smell, and taste — it links the subject to an adjective, not an adverb.
As an adjective, sound means solid, reliable, healthy, or thorough. A sound argument is one that is logically valid. A sound building is structurally solid. Sound advice is trustworthy and sensible. This adjective sense is especially common in formal, academic, and professional writing.
Example Sentences by Level
| Sentence | Level | Usage note |
|---|---|---|
| I heard a strange sound outside my window last night. | A2 | sound as a countable noun |
| That sounds like a really good idea — let's try it. | B1 | sound as a linking verb + adjective |
| Her pronunciation of difficult sounds improved significantly through regular practice. | B1 | speech sounds in a language learning context |
| The report was based on sound evidence gathered over three years of research. | B2 | sound as an adjective meaning reliable/solid |
| Despite the disruptions, the children were all sound asleep within minutes of the lights going out. | C1 | sound asleep — fixed adjectival phrase meaning deeply asleep |
Collocations
| Collocation | Part of speech | Example |
|---|---|---|
| sound advice | adjective + noun | She gave me some very sound advice about the interview. |
| sound sleep / sound asleep | adjective | After the long hike, he fell into a sound sleep. |
| sound investment | adjective + noun | Property in this area has always been a sound investment. |
| sound knowledge | adjective + noun | Candidates must have a sound knowledge of tax law. |
| make a sound | verb phrase | The cat crept past without making a sound. |
| sound effect | compound noun | The film's sound effects created a powerful atmosphere. |
| background sound | noun phrase | Background sounds can distract learners during online lessons. |
| speech sound | compound noun | English has 44 distinct speech sounds, or phonemes. |
| sound reasoning | adjective + noun | Her sound reasoning convinced the committee to approve the plan. |
| sound the alarm | verb + noun | Scientists have been sounding the alarm about rising sea levels for decades. |
Usage Notes
Sound as a linking verb: When sound means "to seem", it must be followed by an adjective, not an adverb. Say 'that sounds great' — not 'that sounds greatly'. This is one of the most common errors made by intermediate learners.
Sound vs. noise: Both refer to things you can hear, but noise implies something unwanted, loud, or unpleasant ('traffic noise', 'noise pollution'). Sound is neutral and can be pleasant or unpleasant.
Formal adjective use: In academic and professional writing, sound as an adjective ('sound methodology', 'sound argument', 'a sound basis') is extremely common and carries a positive, scholarly register. It is worth learning as a productive collocate.
Sound asleep: This fixed phrase functions as a predicate adjective and is not split by other words. Avoid 'sound deeply asleep' — the phrase is already idiomatic and does not require reinforcement.
Common Mistakes
Watch Out For
That sounds very interestingly.
That sounds very interesting. (linking verb + adjective, not adverb)
She sounded like an expert in the topic.
She sounded like an expert on the topic. (use on a topic, not in with expert)
I could hear a loud noise sound from the engine.
I could hear a loud sound from the engine. (do not combine noise and sound as synonyms in the same noun phrase)