Abstract
Suppressing unwanted background sound is crucial for aural communication. A particularly disruptive type of background sound, informational masking (IM), often interferes in social settings. However, IM mechanisms are incompletely understood. At present, IM is identified operationally: when a target should be audible, based on suprathreshold target/masker energy ratios, yet cannot be heard because target-like background sound interferes. We here confirm that speech identification thresholds differ dramatically between low- vs. high-IM background sound. However, speech detection thresholds are comparable across the two conditions. Moreover, functional near infrared spectroscopy recordings show that task-evoked blood oxygenation changes near the superior temporal gyrus (STG) covary with behavioral speech detection performance for high-IM but not low-IM background sound, suggesting that the STG is part of an IM-dependent network. Moreover, listeners who are more vulnerable to IM show increased hemodynamic recruitment near STG, an effect that cannot be explained based on differences in task difficulty across low- vs. high-IM. In contrast, task-evoked responses near another auditory region of cortex, the caudal inferior frontal sulcus (cIFS), do not predict behavioral sensitivity, suggesting that the cIFS belongs to an IM-independent network. Results are consistent with the idea that cortical gating shapes individual vulnerability to IM.
Highlights
Perceptual interference from background sound, called auditory masking, has long been known to impair the recognition of aurally presented speech through a combination of at least two mechanisms
We sought to differentiate between Informational masking (IM)-independent parts of the brain whose activation levels are equivalently driven by lowor high-IM, vs. IM-dependent regions whose activation levels correlate with individual IM-vulnerability
The current data confirm that cortical regions at or near superior temporal gyrus (STG) and caudal inferior frontal sulcus (cIFS) engage during masked speech comprehension tasks (Scott et al, 2004, 2006, 2009; Kerlin et al, 2010; Ding and Simon, 2012; Mesgarani and Chang, 2012; Michalka et al, 2015; Noyce et al, 2017; Rowland et al, 2018; Zhang et al, 2018)
Summary
Perceptual interference from background sound, called auditory masking, has long been known to impair the recognition of aurally presented speech through a combination of at least two mechanisms. Energetic masking (EM) occurs when target and masker have energy at the same time and frequency, such that the masker swamps or suppresses the auditory nerve activity evoked by the target (Young and Barta, 1986; Delgutte, 1990). Listeners experience IM when the masker is target-like (e.g., hearing two women talk at the same time vs hearing out a female in the background of a male voice; Brungart, 2001b) or when the listener is uncertain about perceptual features of the Informational Masking Linked to STG target or masker [e.g., trying to hear out a target with known vs unexpected temporal patterning, cf Lutfi et al (2013)]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
