Welcome to our pronunciation lesson on the English consonants theta and eth. The theta sound, written as [θ], is voiceless and appears in words like 'third'. The eth sound, written as [ð], is voiced and appears in words like 'mother'. Both sounds are made by placing the tongue tip between the upper and lower teeth. The key difference is that [ð] involves vocal cord vibration while [θ] does not.
Let's practice words with the theta sound. Remember to place your tongue tip lightly between your teeth and blow air gently without using your voice. Listen and repeat: thing, think, thought, thief, third, nothing, through, three. Notice how the tongue position stays consistent for all these words.
Now let's practice words with the eth sound. This time, place your tongue tip between your teeth and use your voice. You should feel vibration in your throat. Listen and repeat: the, this, that, thus, other, another, father, mother. Notice the vibration that makes this sound different from theta.
Let's practice comparing similar sounds. Listen carefully to the difference between regular consonants and the theta and eth sounds. Notice how mouse and mouth differ only in the final sound. The same pattern appears in sum versus thumb, sick versus thick. For the eth sound, compare day with they, dare with there. The key is the tongue position between the teeth and whether you use your voice or not.