The Role of Average Fundamental Frequency Difference on the Intelligibility of Real-Life Competing Sentences

The average fundamental frequency separation (∆f_o) between two competing voices has been shown to provide an important cue for target-speech intelligibility. However, some of the previous investigations used speech materials with linguistic properties and f_o characteristics that may not be typical of realistic acoustic scenarios. This study investigated to what extent the effect of ∆f_o generalizes to more real-life speech.

Real-life sentences and a well-controlled method for manipulating the acoustic stimuli were employed. Fifteen young normal-hearing native Danish listeners were tested in a two-competing-voices sentence recognition task at several target-to-masker ratios (TMRs) and ∆f_os.

Compared to previous studies that addressed the same experimental scenario with less realistic speech materials, the present results showed only a moderate effect of ∆f_o at negative TMRs and a negligible effect at positive TMRs. An analysis of the employed stimuli showed that a large ∆f_o effect on the target speech intelligibility is only observed when the competing sentences have highly synchronous f_o trajectories, which is typical of the artificial speech materials employed in previous studies.

Overall, the present results suggest a relatively small effect of ∆f_o on the intelligibility of real-life speech, as compared to previously employed artificial speech, in two-competing-sentences conditions.