(a) Participants were instructed to attended right or left ear (counterbalanced) and ignore the other. To-be-attended stimulus was always natural Hebrew speech, and multiple choice questions about the content were asked at the end of each trial. The task-irrelevant ear was always presented with hierarchical frequency-tagging stimuli in two conditions: Structured and Non-Structured. (b) Example of intelligible (Structured) speech composed of 250 ms syllables in which 4 levels of information are differentiated based on their rate: acoustic/syllabic, word, phrasal, and sentential rates (at 4, 2, 1, and 0.5 Hz, respectively). Translation of the two Hebrew sentences in the example: ‘Small puppies want a hug’ and ‘A taxi driver turned on the meter.’ Control stimuli were Non-Structured syllable sequences with the same syllabic-rate of 4 Hz. (c) Representative sound wave of a single sentence (2 s). Sound intensity fluctuates at the rate of 4 Hz. (d) Modulation spectrua of the speech envelopes in each condition. Panels b and c are reproduced from Figure 1A and Figure 1B of Makov et al., 2017. Panel d has been adapted from Figure 1C of Makov et al., 2017.