The 'th' Sounds: δ and θ

English hides two different sounds under one spelling. The th of this buzzes — your vocal cords vibrate — while the th of thin is a silent hiss. English never bothers to tell them apart in writing, so most speakers have never consciously noticed the difference. Greek, by contrast, gives each sound its own letter: δ (delta) is the voiced one [ð], and θ (theta) is the voiceless one [θ]. The good news is that you already produce both sounds effortlessly. The whole task on this page is learning to map them reliably onto the two Greek letters — and, crucially, learning not to turn δ into a hard English d.

δ (delta) = the voiced 'th' of this [ð]

Put your tongue lightly between or just behind your teeth, let the air flow continuously, and switch your voice on. That buzzing sound is δ. It is exactly the initial consonant of English this, that, the, those, mother, weather.

The single most common Greek word in the language, δεν ("not"), begins with this sound. If you can say the English word then and simply not round it off into a full d, you have δεν right: [ðen].

θ (theta) = the voiceless 'th' of thin [θ]

Same tongue position, same continuous airflow, but now your voice is off — pure breath. That hiss is θ, the sound at the start of thin, think, three, thank, bath, math.

The future-tense particle θα — which you will meet in almost every sentence about tomorrow — is just this hiss plus an a: [θa]. Say the th of bath, add "ah", and stop your voice from creeping in.

The one contrast that matters: voicing

δ and θ are made in the identical place with the identical airflow. Only your voice box distinguishes them — on for δ, off for θ. Linguists call this a voicing contrast, and it is the same relationship English has between z and s, or v and f. Feel it: put a hand on your throat and say a long "δδδδ" — you feel the buzz. Now say "θθθθ" — silence, just breath.

Greek keeps a handful of near-minimal pairs that ride entirely on this contrast. The cleanest is δέμα ("parcel") versus θέμα ("topic, matter") — identical but for the first sound's voicing:

Why English speakers get this wrong

You would think English speakers would sail through, since both sounds live in English already. The trap is subtler than a missing sound — it is interference from the letter shape and from the d habit.

Because δ looks like a rounded d, and because the sound it makes has no dedicated letter in English, learners' hands and mouths default to the nearest English letter they know: a hard [d]. So δεν comes out as "den", δώρο as "doro", δρόμος as "dromos". To a Greek ear this is jarring — it sounds foreign, and worse, it collides with ντ, the digraph that genuinely is [d] (or [nd]). The pair δίνω ("I give") [ˈðino] versus ντύνω ("I dress") [ˈdino] shows how much rides on it: swap the soft δ for a hard d and you have said a different verb.

The mirror-image error hits θ. English th is voiced in the most frequent little words — the, this, that, they — so English speakers have a reflex to voice any th. Carried into Greek, that reflex turns θ into δ: θέλω becomes "delo", θα becomes "da". Keep θ crisp and breathy.

A note on continuous airflow

Both δ and θ are fricatives — the air never fully stops, it squeezes through a narrow gap and keeps flowing. A [d], by contrast, is a stop: the tongue seals the airflow completely and then releases it with a little burst. This is the physical heart of the mistake. When you make a hard [d] for δ, you are stopping the air where you should be letting it stream. Aim to sustain δ and θ — you should be able to hold either one for as long as your breath lasts, humming (δ) or hissing (θ). You cannot hold a [d]; it pops and is gone.

Common Mistakes

1. Pronouncing δ as a hard English d. This is the number-one error. δεν is [ðen], not "den".

2. Voicing θ into δ. English's habit of voicing th in the/this leaks over. θα is [θa], not [ða].

3. Devoicing δ into θ. The reverse slip — turning the buzz off — swaps δώρο ("gift") toward a non-word.

4. Reading δ and θ as one blended 'th'. Because English fuses them, learners guess randomly. Anchor each: δ = this, θ = thin, and check with the throat test.

Key Takeaways

• δ = [ð], the voiced 'th' of this — vocal cords on, air flowing. Words: δεν, δώρο, δρόμος.
• θ = [θ], the voiceless 'th' of thin — vocal cords off, pure breath. Words: θέλω, θα, θάλασσα.
• The only difference between them is voicing; the throat test (buzz vs. breath) settles every case.
• Never pronounce a bare δ as a hard English d — that [d] sound belongs to ντ, and δίνω vs. ντύνω proves the words are different.
• Resist English's reflex to voice every th: keep θ crisp so θα stays [θa], not [ða].