Assessment protocols for forward masking in Frequency-Following Response

ABSTRACT 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.