Figure 4: Mean listening effort ratings (effort scale categorical units, ESCUs) of 10 participants and the reference (solid line), and streaming condition (dashed line) as a function of signal-to-noise ratio (i-SNR) of sentences and noise; the areas around the mean functions show the spread (standard deviation). The ESCU range from 1=“effortless” to 13=“extremely effortful”; in addition, there is the response category ‘noise only’ (no).