Introduction Prenatal exposure to the Zika virus can impair neurodevelopment and cause auditory damage. Objective To analyze the frequency-following response (FFR) and the auditory behavior (with the LittlEars ® questionnaire) of children with and without prenatal exposure to Zika virus infection. Methods A total of 30 children participated in the present study, divided into 3 groups: 10 children with microcephaly and prenatal exposure to the Zika virus; 10 normocephalic children with prenatal exposure to the Zika virus; and 10 children with no evidence of prenatal exposure to the virus. The FFR test was performed with the /da/ syllable. The LittlEars ® questionnaire was used with parents/guardians. Results For the FFR measurements, there was no difference between the groups. The children with exposure to the Zika virus presented a final score in the questionnaire below what is expected from children with normal hearing. A significant difference was observed for the final, semantic, and expressive scores between the group with microcephaly and the other groups. A strong negative correlation was seen between the LittlEars ® questionnaire final score and the FFR measurements for the group with microcephaly when compared with the other groups. Conclusion Children exposed to the Zika virus, with and without microcephaly, presented FFR patterns similar to what was seen in children with no evidence of virus exposure. However, they showed signs of immature auditory behavior, suggesting auditory development delay.

No abstract

Background Forward masking occurs when noise is presented before the target signal, making the latter difficult to be perceived. It is related to temporal auditory processing and consequently to speech recognition in noisy environments, which may decline with age. Interest in forward masking has grown in the last years. Studies investigate psychoacoustic and electrophysiological recordings in different age- groups. Purpose The purpose of the study was to investigate the effect of forward masking on frequency following response (FFR) as a function of age. Research Design Cross-sectional analytical observational study. Study Sample We assessed 69 normal-hearing participants of both genders assigned to three groups: 40 young individuals (aged 18-25 years, mean age = 22 years 8 months), 21 middle-age individuals (aged 25-55 years, mean age = 37 years 2 months), and 8 seniors (aged <55 years, mean age = 65 years 3 months). Intervention FFRs were recorded using the /da/ syllable with and without noise. Data Collection and Analysis The /da/ syllable and speech-shaped noise were monaurally presented to the participants' right ears through ER-3a insert earphones. Electrodes were placed in M1 and M2 (-), Fz (+), and Fpz (ground). Acquisition occurred under two conditions: (1) the/da/ syllable presented without the noise and (2) the /da/ syllable presented 4 msec after the noise. Results Data show that (1) considering the mean values of all participants, there was a significant latency delay of all waves (PV, A, PW, PX, PY, PZ, and O) when the /da/ syllable was presented 4 msec after the masking noise as compared with the condition without noise, that is, forward masking occurred in all components of the FFR responses, and (2) for the youngest group and the middle-age group, forward masking was seen for all waves, except PX in the latter one; for the senior group, an irregular pattern was observed (presence of forward masking in PA, PY, PZ, and O). This pattern may be due to an aging effect on FFR responses even without noise presence, which makes it more difficult to identify forward masking effect in this population. Although it is well documented in the literature that forward masking increases with age, this is less evident on FFR recordings in the senior population. Conclusions An aging effect was identified in FFR responses. Forward masking was identified in FFR responses of all groups but less evident in senior population.

Purpose: to investigate forward masking by comparing latencies values of positive and negative peaks in frequency-following responses (FFR) recordings, in normally hearing young adults. Methods: from a database, 20 FFR recordings were selected, 10 being from men, and 10 from women, aged 18 to 25 years, with normal hearing. They were qualitatively analyzed by two experienced researchers and also analyzed, according to two different protocols of recording identification: (i) predominance of positive peaks - PV, A, PW, PX, PY, PZ, and O waves; and (ii) predominance of negative peaks - V, A, C, D, E, F, and O waves. The Shapiro-Wilk normality test, the Wilcoxon test, and the Student’s t-test were conducted, by adopting the significance level of p<0.05. Results: the comparative analysis of latency peak values did not reveal any significant difference between the studied protocols. However, the standard deviation was higher for absolute latency values as compared to negative peaks, suggesting an inverted pattern of what was expected. Conclusion: forward masking was identified in both proposals and the protocol of predominant positive peaks was less variable.

YELLAMSETTY, Anusha; BIDELMAN, Gavin M. Brainstem correlates of concurrent speech identification in adverse listening conditions. Brain research, v. 1714, p. 182-192, 2019.