Effect of Forward Masking on Frequency Following Response as a Function of Age

Abstract

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