The maintenance of clear speech in naturalistic conversations.

Clear speech is a style that speakers adopt when talking with listeners whom these speakers anticipate may have a problem understanding speech. This study examines whether native English speakers use clear speech in conversations with non-native English speakers when native speakers are not explicitly asked to use clear speech (i.e., clear speech elicited with naturalistic methods). The results of the study suggest that native English speakers use clear speech in conversations with non-native English speakers even when native speakers are not explicitly asked to. Native English speakers' speech is more intelligible in the early portions of the conversations than in the late portions of each conversation. Further, the speakers "reset" to clearer speech at the start of each Diapix picture. Additionally, acoustic properties of the speech are examined to complement the intelligibility results. These findings suggest the instigation of clear speech may be listener-driven but the maintenance of clear speech is likely more speaker-driven.

Non-native English listeners' adaptation to native English speakers.

Listeners often have difficulty understanding unfamiliar speech (e.g., non-native speech), but they are able to adapt to or improve their ability to understand unfamiliar speech. However, it is unclear whether non-native listeners demonstrate adaptation to novel native English speech broadly with relatively limited exposure. Thus, this study examines non-native English listeners' adaptation to native English speakers and whether talker variability affects adaptation. Results suggest that while greater variability initially disrupts non-native English listeners' perception of native English speakers, listeners are able to rapidly adapt to novel speakers and exposure to greater variability could result in cross-talker generalization.

Lexical Diversity, Lexical Sophistication, and Predictability for Speech in Multiple Listening Conditions.

When talkers anticipate that a listener may have difficulty understanding their speech, they adopt a speaking style typically described as "clear speech." This speaking style includes a variety of acoustic modifications and has perceptual benefits for listeners. In the present study, we examine whether clear speaking styles also include modulation of lexical items selected and produced during naturalistic conversations. Our results demonstrate that talkers do, indeed, modulate their lexical selection, as measured by a variety of lexical diversity and lexical sophistication indices. Further, the results demonstrate that clear speech is not a monolithic construct. Talkers modulate their speech differently depending on the communication situation. We suggest that clear speech should be conceptualized as a set of speaking styles, in which talkers take the listener and communication situation into consideration.

Effective humoral immune response from a H1N1 DNA vaccine delivered to the skin by microneedles coated with PLGA-based cationic nanoparticles.

Intradermal DNA vaccination is a promising method of immunization that overcomes some practical drawbacks of conventional intramuscular vaccinations. However, it is difficult to deliver DNA vaccines to target cells in the skin and polyplexes. This study outlines the development of an intradermal pH1N1 DNA vaccine delivery platform using microneedles (MNs) coated with a polyplex containing poly lactic-co-glycolic acid/polyethyleneimine (PLGA/PEI) nanoparticles (NPs). Stainless steel MNs with enhanced hydrophilicity have been manufactured by silanization, which improves coating efficiency. MNs coated with the polyplex encapsulating pDNA vaccine were prepared by optimizing the N/P ratio, with a 6:1 ratio showing the highest transfection efficiency in mammalian cells. Polyplexes were coated on MNs without severe aggregation of the polyplex in the dry form. The coated polyplex rapidly dissolved in porcine skin (within 5min) and induced a greater humoral immune response than that of intramuscular polyplex delivery or naked pH1N1 DNA vaccine delivery by a dry-coated MN. These results indicate that intradermal delivery of pDNA vaccines within a cationic polyplex coated on MNs has potential in skin immunizations.