The speaker’s identity (who the speaker is) and linguistic information (what the speaker is saying) are essential to daily communication. However, it is unclear whether and how listeners process the two types of information differently in speech perception. The present study adopted a passive oddball paradigm to compare the identity and linguistic information processing concerning neural resource involvements and hemispheric lateralization patterns. We used two female native Mandarin speakers’ real and pseudo-Mandarin words to differentiate the identity from linguistic (phonological and lexical) information. The results showed that, in real words, the phonological-lexical variation elicited larger MMN amplitudes than the identity variation. In contrast, there were no significant MMN amplitude differences between the identity and phonological variation in pseudo words. Regardless of real or pseudo words, the identity and linguistic variation did not elicit MMN amplitudes differences between the left and right hemispheres. Taken together, findings from the present study indicated that the identity information recruited similar neural resources to the phonological information but different neural resources from the lexical information. However, the identity and linguistic information processing did not show a particular hemispheric lateralization pattern at an early pre-attentive speech perception stage. The findings revealed similarities and differences between linguistic and non-linguistic information processing, contributing to a better understanding of speech perception and spoken word recognition.

A theta/gamma oscillatory neural mechanism has been postulated to explain the auditory sampling of hierarchical syllable-phoneme structure with corresponding speech rates or linguistic hierarchies (theta for syllable and gamma for phoneme). Yet, whether such a mechanism is generalizable to Mandarin Chinese, a language that both has suprasegmental phonemes in the form of lexical tones and contains more monosyllabic words, which may lead to higher reliance on either phonemic-level or syllabic-level perceptual representations, is unclear. In this study, we applied transcranial electric stimulation with either theta or gamma alternating currents (tACS) to bilateral auditory cortices in healthy Mandarin-speaking participants during a consonant or tone identification task in quiet or noisy environments. Results showed that theta tACS impaired consonant identification in quiet, specifically, and generally prolonged reaction times across tasks and environments. Gamma tACS, however, only delayed tone identification in quiet. Besides, both theta and gamma tACS modulated perceptual decision-making parameters, leading to increased boundary thresholds (cautiousness of decision) and altered response biases in the perceptual decision of both consonants and tones, as evidenced by the hierarchical drift-diffusion model (HDDM). These findings indicate that theta oscillations causally support the perception of Mandarin syllables, with consonants and lexical tones presumably embedded in syllable-level representations, regardless of task difficulty. Gamma activity, however, is presumably engaged in supporting fast-changing and fine-grained acoustic features in a modulatory manner. Significance Statement: How the brain samples speech features for perception is a key question in language neuroscience. Previous research has shown that theta and gamma brain activity support the perception of suprasegmental syllables and segmental phonemes, corresponding to their length or linguistic hierarchy. However, for Mandarin, the existence of suprasegmental phonemes (lexical tones) and the large number of monosyllabic words can either lead to higher reliance on gamma oscillations for phoneme perception, or higher dependence on theta oscillations for holistic syllable integration. With the combination of brain stimulation to selectively modulate theta/gamma auditory activity and phoneme identification tasks, this study reveals a causal role of theta activity in supporting holistic syllable-based Mandarin phoneme perception, yet gamma engagement is modulatory.

Introduction: In order to study the impact of social factors on the evolution of the epidemic, this paper takes the COVID-19 in Hubei Province of China as an example to study the impact of social factors such as the permanent population, universities, hospitals, the distance between Wuhan seafood market and 17 cities in Hubei Province, and the distribution of medical supplies on the COVID-19. This is of great significance for helping to develop effective prevention and control measures and response strategies, ensuring public health and social stability.Methods: Time series regression analysis is used to study the impact of various factors on the epidemic situation, multidimensional scale analysis is used to assess the differences among provinces, and Almon polynomial is used to study the lag effect of the impact.Results: We found that these cities can be divided into three groups based on the number of confirmed cases and the time course data of the cases. The results verify that these factors have a great impact on the evolution of the COVID-19.Discussion: With the increase in the number of universities, the number of confirmed cases and new cases has significantly increased. With the increase in population density, the number of new cases has significantly increased. In addition, the farther away from the Wuhan seafood market, the fewer confirmed cases. It is worth noting that the insufficient increase in medical supplies in some cities still leads to a significant increase in new cases. This impact is regional, and their lag periods are also different. Through the comparison with Guangdong Province, it is concluded that social factors will affect COVID-19. Overall, promoting the construction of medical schools and ensuring the reasonable distribution of medical supplies is crucial as it can effectively assist decision-making.

A theta/gamma neural activity mechanism has been postulated to explain the auditory sampling of hierarchical syllable-phoneme structure with corresponding speech rates or linguistic hierarchies (theta for syllable and gamma for phoneme). Yet, whether such a mechanism is generalizable to Mandarin Chinese, a tonal language, where lexical tones are at syllable length but function as phonemic cues, is unclear. In this study, we applied transcranial alternating current stimulation (tACS) with theta or gamma currents over bilateral temporal areas in healthy Mandarin-speaking participants during a consonant or tone identification task in quiet or noisy environments. Results showed that theta tACS impaired both consonant and tone identification in quiet and prolonged reaction times across tasks and environments. Moreover, it reduced the psychometric slope for consonant identification in quiet, indicating decreased perceptual sensitivity and less distinct category boundaries. Gamma tACS, however, only delayed tone identification in quiet. Besides, both theta and gamma tACS modulated perceptual decision-making parameters in quiet, leading to increased boundary thresholds (cautiousness of decision) and altered response biases in the perceptual decision of both consonants and tones, as evidenced by the hierarchical drift-diffusion model. These findings indicate that the perception of Mandarin consonants and lexical tones is causally supported by syllable-length theta activity, presumably reflecting syllable-level holistic representations, regardless of environment. Gamma activity, however, is presumably engaged in supporting fast-changing and fine-grained acoustic features in a modulatory manner. Theoretical explanations from historical linguistics and implications for clinical or educational applications are also provided.

Listeners identify speakers more accurately in a familiar language than in an unfamiliar one, a phenomenon known as the language-familiarity effect. Whether voice identity learned in one language can be recognized when the same speaker speaks another language, and how familiarity with the learning and test languages affects this transfer, remains unclear. Three experiments used a speaker identification paradigm in which native Mandarin participants learned speakers' voices in one language and were tested on the same speakers speaking another language. Experiment 1 examined transfer from English (a proficient second language) to Mandarin (native) and Cantonese (unfamiliar). Experiment 2 manipulated the learning language (Mandarin, English, or Cantonese) and the test language. Experiment 3 replaced Cantonese with Russian to rule out phonological similarity. Across all experiments, identification accuracy was above chance in every test-language condition, indicating that voice identity can transfer across languages. In Experiment 1, reaction times for Mandarin and English were shorter than for Cantonese. In Experiment 2, learning language and test language interacted on both accuracy and reaction times. When the learning language was Mandarin or English, performance for Cantonese was worse than for English; when the learning language was Cantonese, reaction times for Mandarin were longer than for Cantonese and English. Experiment 3 replicated this reversal with Russian. These findings suggest that language-general acoustic information may support basic transfer, while language-specific information may support better performance, shedding light on how linguistic and non-linguistic information interact during voice perception.