A thoughtful question came in recently from an instructor reviewing the Audio Lab:
“I can’t seem to find certain sounds like the schwa /ə/ or diphthongs like /oɚ/. Am I missing something?”
It’s a fair question—and an important one—because it gets to the core of how the P-ESL system prioritizes targets.
The short answer is: you’re not missing anything. Some sounds are intentionally not included as primary targets. The reason has less to do with whether those sounds exist in English, and more to do with how consistently they appear as errors across speakers from different language backgrounds.
How Target Sounds Were Selected
The Audio Lab is based on the research behind the Phonological Assessment of Foreign Accent, developed by Dr. Arthur Compton. In that work, the goal was not to catalog every possible sound in American English, but to identify the sounds that most reliably interfere with intelligibility across a wide range of native languages.
In other words, the focus is on high-impact, high-frequency error patterns—the sounds that consistently show up as problematic and, when corrected, produce meaningful improvements in clarity.
This is why you will see strong representation of certain consonants and vowels that are known to vary significantly across languages. These sounds tend to produce noticeable communication breakdowns when misarticulated.
Why the Schwa /ə/ Isn’t a Primary Target
The unstressed schwa vowel /ə/ is a good example of how this prioritization works.
In Dr. Compton’s research, the schwa did not emerge as a consistent, high-impact error sound across native language groups. That doesn’t mean it never causes issues—it certainly can—but it wasn’t identified as a reliable source of intelligibility breakdown at the same level as other targets.
Because of that, it was not included as a primary training focus in the Audio Lab.
Instead, emphasis was placed on the stressed vowel /ʌ/, which did appear frequently as an error across languages. This distinction matters. The /ʌ/ vowel requires more precise articulatory control and tends to carry more perceptual weight in stressed syllables.
Here’s the practical takeaway:
When clients improve their production of the stressed /ʌ/ vowel, that accuracy often generalizes to the unstressed schwa position.
This reflects a broader principle in pronunciation training:
Work on the high-impact, high-control targets, and allow lower-impact variations to improve through generalization.
What About Sounds Like /oɚ/ and Other Variants?
Diphthongs and r-colored vowels—like /oɚ/—can raise similar questions.
Again, the issue is not whether these sounds exist or matter, but whether they:
- Appear consistently as errors across speakers, and
- Significantly disrupt intelligibility when misproduced
Some of these combinations are better understood as variations or extensions of core phoneme patterns, rather than standalone targets. For example, r-colored vowels often relate back to underlying /r/ production and vowel shaping—both of which are directly targeted in the system.
So instead of treating every possible variation as its own category, the approach is to:
- Target the core phoneme behaviors (e.g., /r/, vowel positioning)
- Allow more complex or context-dependent forms to improve through structured practice and carryover
But What If You Hear the Error in Your Client?
Here’s where your clinical judgment comes in—and this is critical.
Just because a sound is not included as a primary target in the Audio Lab does not mean it should be ignored if it shows up in your client’s speech.
In fact, you should absolutely:
- Document it in your assessment notes
- Track its occurrence and impact on intelligibility
- Address it directly if it is affecting communication clarity
The difference is that you won’t treat it as a completely separate system. Instead, you apply the same instructional framework used for all phoneme targets:
- Establish clear articulatory placement
- Build auditory discrimination
- Practice in structured progression (isolation → words → phrases → conversation)
- Monitor and reinforce carryover
This keeps your instruction consistent and efficient, without overcomplicating the training process.
A More Strategic Way to Think About “Missing” Sounds
It’s tempting – especially for clinicians trained in detailed phonetic analysis – to want a one-to-one match between every possible sound and a corresponding training module.
But that approach can quickly become overwhelming for both instructor and client.
The P-ESL system takes a different stance:
- Prioritize what moves intelligibility the most
- Focus on patterns, not just individual sounds
- Use generalization as a tool, not an afterthought
This keeps the attention on what actually changes how a speaker is understood in real-world communication.
Bottom Line
If you don’t see a sound like /ə/ or /oɚ/ in the Audio Lab, it’s not an oversight. It’s a reflection of how target sounds were selected based on their impact and consistency across speakers.
At the same time, your role as the instructor is not limited to a fixed list. If a client presents with a pronunciation pattern that affects intelligibility, you address it—using the same structured, evidence-aligned approach that drives progress across all targets.
That balance – research-informed prioritization combined with clinical flexibility – is what makes the P-ESL system both efficient and adaptable.