Most languages prefer a vowel after every consonant. English does not. sixth stacks four consonant sounds with no vowel to rest on: /s-ɪ-k-s-θ/. Adding a helping vowel ('sik-suh-th') is the giveaway accent.
The Rule: Do not insert a vowel between the consonants. Keep your tongue moving through the cluster in one breath, ending with the tongue tip between the teeth for the final /θ/.
The hard endings
Practice these words:
More: eighth, depths, texts, twelfths, strengths, lengths.
A practical shortcut
Build the cluster slowly, then speed up. For months, say 'mun' + 'th' + 's' and blend: /mʌnθs/. Many natives simplify it to /mʌns/ in fast speech, so a light /θ/ is fine - just never add a vowel.
Why Does This Happen?
Ordinal numbers add -th to the number, which crashes the /θ/ into whatever consonant was already there. That is how English ends up with /fθ/, /ksθ/ and /lfθ/. They feel impossible at first, then automatic with practice.
Quick Summary
| Word | Cluster | Tip |
|---|---|---|
| fifth | /fθ/ | fif + th, no vowel |
| sixth | /ksθ/ | siks + th |
| months | /nθs/ | mun + th + s |
| clothes | /ðz/ | often just /kloʊz/ |
Want to train your ear and mouth on these patterns? Try our interactive pronunciation practice and hear each sound in context.