Research

My research focuses on phonetic detail within phonology and how it fits into representations, developing a phonological model for what that representation looks like and how it can account for observed experimental results, typological patterns, and diachronic patterns.

To probe this model, I look at phonetic correlates of phonological contrasts and other predictors in production, how they influence perception, how they shift based on experimental manipulations, and how they vary across languages. Some of these patterns provide an additional line of evidence establishing pathways of diachronic developments.

Phonetics in Phonology

I am developing a connectionist model to account for the representation of phonetic details and the resulting patterns in speech perception and production, based on what factors are connected to phonetic details and which phonetic details are specified in that connection. This model can help explain both synchronic patterns and patterns of change.

Phonetic details in the phonological representation are linked with features rather than individual sounds. I demonstrate that shifts are generalized at the featural level: Exposing listeners to raised or lowered F1 or F2 in one vowel produces corresponding shifts in vowels that match in height or backness, respectively. Listeners extend shifted formants across speakers; their subsequent perception of a novel talker reflects the relative formants of exposure stimuli based the training talker's apparent vowel space.

Factors beyond phonological contrasts can also exhibit associated phonetic details. I show that longer vowel duration increases listeners' perception that a stimulus item is a noun rather than a verb, both for real words and nonce words. Many apparent word-specific effects can be explained by factors like part of speech and how lexical frequency interacts with lexical access. Items with higher lexical frequency can achieve full activation based on weaker phonetic matches, resulting in frequency biases, particularly for reduced forms. Recent exposure to a word broadens the acceptable phonetic realizations of the phonological categories within that word based on raising the activation level.

Several lines of evidence support an articulatory model for phonological representations. Articulatory Phonology provides a model which is well suited to explaining links between phonological categories and their phonetic realization. I demonstrate that perceptual evidence also supports a gestural representation; the duration of aspiration contributes both to perception of the consonant as well as perception of following vowel duration. These dual effects are consistent with listeners perceiving the aspiration as the overlap between the vowel and a consonant gesture.

Evidence for Sound Changes

Experimental data, in combination with traditional comparative methods, can elucidate questions about sound change, and in turn, patterns of sound change can further our understanding of biases in phonological interpretation of phonetic input. There are broad parallels between diachronic developments and synchronic patterns of perception and production, which make experimental data a useful source of complementary evidence for reconstructions. The typological patterns of broadly observed phenomena, such as voicing-conditioned vowel duration, can also provide evidence for potential pathways of development and suggest the phonetic characteristics of reconstructed phonemes.

I also use synchronic parallels to help test specific reconstructions, which is particularly useful for changes without many clear reconstructed parallels, such as the developments of the Proto-Indo-European laryngeals, which I investigated in my dissertation. I have also demonstrated a parallel for the sound change proposed in Winter's Law, with vowel lengthening before voiced unaspirated stops and not before voiced aspirated stops. While Hindi is often taken as representative of how voiced aspirated stops influence vowel duration, I demonstrate that Telugu differs from Hindi and provides a duration pattern that parallels Winter's Law. The different realizations of voiced aspirated stops in Hindi and Telugu further help illustrate crucial phonetic differences in sounds that are often treated as equivalent.

Typology

Cross-linguistic typologies help shed light on what drives phonetic patterns and how they are represented. Some effects are consistent across languages and can be explained as purely mechanical, while others must be phonologically specified. This typological information also helps us better understand the variation which can exist in languages of the world.

My typological focus is on timing patterns. While a large body of work demonstrates effects of factors like vowel height and voicing of the following consonant, there is no typological collection pulling together all of these language-specific studies to examine how the size of each effect varies across languages and how it interacts with different predictors. In a paper on voicing-conditioned vowel duration, I show that the size of this effect varies substantially across languages. There is also variation within each language; the size of the voicing effect with stops is predictive of its size with fricatives in the same language, but the size of the effect word-finally is not predictive of its size word-medially.

I also contribute to a research group working on A'ingae, a South American language isolate; we have produced the first instrumentally based overview of its phonological system and continue to elucidate both areally motivated characteristics of its phonology and unique characteristics such as narrative use of syllable-level falsetto.

Phonetics and Effects of Methodology

Because of restrictions on travel and in-person research during the Covid-19 pandemic, many researchers have started making remote recordings, using a range of methods. It is important to know how these methods might affect acoustic measurements, particularly for underdocumented languages, but also in any phonetic research. Variation might arise either because of different recording devices or because of the software used to make recordings. In a collaborative project, I led the Yale fieldwork group in investigating how varied recording methods impact phonetic measurements. Different recording devices and software programs have a substantial impact on many of the measurements that we tested, including measurements of duration, frequency, and aperiodic noise.

I have also examined how commonly used headphone checks impact results in online perception experiments. Headphone checks exclude many participants, which alters participant demographics such as gender, age, and geographic region. However, these exclusions do not increase effect sizes for most characteristics; for many perception studies, there is little evidence that headphone checks provide any benefit.

In addition to effects of how data is collected, methods of analysis can impact results. In a collaborative project, I demonstrated that some apparent individual differences in phonetic convergence are likely to be an artifact of the frequently used difference-in-difference method for measuring convergence.