Comparing dichotic listening and monaural degraded speech in measuring ear dominance

Purpose: The aim of this study was to compare three different methods for assessing ear dominance and analyse the relationship between handedness and various ear dominance values. Methods: In a group of neurotypical, Hungarian adults including right-handed (N=38), left-handed (N=24) and ambidextrous (N=10) men and women, handedness was assessed by a short form of the Edinburgh Handedness Inventory, whereas ear dominance was assessed by dichotic tests and two types of degraded speech stimuli (sine-wave and vocoded speech, generated from trisyllabic Hungarian words) presented monaurally. Results: Although the majority of participants had a right ear advantage using each of the three methods, characteristics of ear dominance differed depending on the assessment method. The three different ear dominance indices were uncorrelated with one another. Handedness was weakly related to dominance measured by monaural sine-wave stimuli and unrelated to that measured by monaural vocoded and dichotic stimuli. Crossed dominance was observed in a substantial proportion of participants (35-46%, depending on the type of ear dominance). Analysis of the perception of degraded speech revealed a remarkable interindividual variability and a learning transfer between sine-wave and vocoded speech. Conclusion: The use of monaural degraded speech stimuli reveals different forms of ear dominance compared with dichotic tests, which suggests that ear dominance is strongly task-dependent. Handedness is not strongly correlated with any form of ear dominance. The high prevalence of crossed hand-ear dominance suggests that this type of crossed dominance is a normal variant rather than a maladaptive trait. The observed learing transfer between the two types of degraded stimuli might be mediated by domain-general mechanisms.