Definition:
Intelligibility is the degree to which a listener can accurately perceive what a speaker has said — the extent to which the spoken message is correctly decoded. In pronunciation research, intelligibility is carefully distinguished from two related but different constructs: accentedness and comprehensibility.
Three Related Constructs
| Construct | Question | Measured by |
|---|---|---|
| Intelligibility | Is the message decoded correctly? | Listener’s ability to transcribe/repeat what was said |
| Comprehensibility | How hard does the listener have to work? | Listener’s perceived effort ratings |
| Accentedness | How foreign does the speaker sound? | Listener’s ratings of native-likeness |
These three constructs are not the same thing and do not always correlate. A heavily accented speaker may be perfectly intelligible; a less accented speaker may be harder to understand in a noisy environment.
Intelligibility vs. Nativeness as a Teaching Goal
Traditional pronunciation instruction aimed at native-like pronunciation. Intelligibility-based teaching reorients the goal: rather than sounding native, learners should aim to be understood in the communicative contexts they actually face.
In ELF (English as a Lingua Franca) contexts, this means understanding which phonological features are functionally important (affect intelligibility) vs. which are merely markers of accent with little communicative consequence.
What Most Affects Intelligibility
Research consistently identifies these features as having high functional load — affecting intelligibility most:
- Consonants — especially in onset position
- Vowel distinctions that carry meaning (minimal pairs)
- Word stress placement — incorrect stress may prevent word recognition
- Sentence rhythm and connected speech — affecting segmentation
Features that correlate more with accent than intelligibility include: subtle vowel quality differences, final consonant detail, and many suprasegmental features.
Listener Factors
Intelligibility is listener-dependent: a trained or experienced listener may understand a highly accented speaker easily, while a naïve listener of the same L1 background may struggle. This is why exposure and familiarity with non-native accents improves comprehension — a major finding in ELF research.