Auditory Cortex Processes Variation in Our Own Speech

Abstract

As we talk, we unconsciously adjust our speech to ensure it sounds the way we intend it to sound. However, because speech production involves complex motor planning and execution, no two utterances of the same sound will be exactly the same. Here, we show that auditory cortex is sensitive to natural variations in self-produced speech from utterance to utterance. We recorded event-related potentials (ERPs) from ninety-nine subjects while they uttered “ah” and while they listened to those speech sounds played back. Subjects' utterances were sorted based on their formant deviations from the previous utterance. Typically, the N1 ERP component is suppressed during talking compared to listening. By comparing ERPs to the least and most variable utterances, we found that N1 was less suppressed to utterances that differed greatly from their preceding neighbors. In contrast, an utterance's difference from the median formant values did not affect N1. Trial-to-trial pitch (f0) deviation and pitch difference from the median similarly did not affect N1. We discuss mechanisms that may underlie the change in N1 suppression resulting from trial-to-trial formant change. Deviant utterances require additional auditory cortical processing, suggesting that speaking-induced suppression mechanisms are optimally tuned for a specific production.

The effects of stimulus complexity on the preattentive processing of self-generated and nonself voices: An ERP study

“…Therefore, this system allows for the differentiation between self-generated and external stimulation Ford & Mathalon, 2004;Ford et al, 2007;Heinks-Maldonado et al, 2005;HeinksMaldonado et al, 2007). On the contrary, if the voice feedback and the predicted sensory consequences do not match, an error signal is generated, and hence auditory cortical suppression is reduced (i.e., auditory activity is increased; Behroozmand, Karvelis, Liu, & Larson, 2009;Eliades & Wang, 2008;Heinks-Maldonado et al, 2005;Heinks-Maldonado et al, 2007;Sitek et al, 2013). Complementing these studies, recent evidence (Tian & Poeppel, 2013 has shown that the operation of the internal feedforward system is not an Bartifact^of overt vocal production, since it operates during articulation imagery.…”

“…These studies have found an N1 amplitude suppression effect during vocal production when compared with the condition of passively listening to prerecorded self-generated voice stimuli Curio, Neuloh, Numminen, Jousmaki, & Hari, 2000;Ford & Mathalon, 2004Ford et al, 2001;Ford et al, 2002;Ford et al, 2007;HeinksMaldonado, Mathalon, Gray, & Ford, 2005;HeinksMaldonado et al, 2007;Houde, Nagarajan, Sekihara, & Merzenich, 2002;H. Liu et al, 2011;Numminen, Salmelin, & Hari, 1999;Sitek et al, 2013;Timm, SanMiguel, Saupe, & Schröger, 2013;Ventura, Nagarajan, & Houde, 2009). Moreover, when participants receive altered self-generated voice feedback, the N1 attenuation effect is smaller than when they listen to intact voice feedback Ford & Mathalon, 2004Ford et al, 2001;Ford et al, 2007;Heinks-Maldonado et al, 2005;HeinksMaldonado et al, 2007;Sitek et al, 2013;Timm et al, 2013).…”

“…H. Chen, Liu, Xu, & Larson, 2007; Z. Chen et al, 2013;Liu, Meshman, Behroozmand, & Larson, 2011;Sitek et al, 2013;Sugimori, Asai, & Tanno, 2013). Abnormalities in the detection of self-generated voice feedback during speech production disrupt verbal communication processes (Lane & Webster, 1991;Moeller et al, 2007;Oller & Eilers, 1988;Schauwers et al, 2004).…”

“…Liu et al, 2011;Numminen, Salmelin, & Hari, 1999;Sitek et al, 2013;Timm, SanMiguel, Saupe, & Schröger, 2013;Ventura, Nagarajan, & Houde, 2009). Moreover, when participants receive altered self-generated voice feedback, the N1 attenuation effect is smaller than when they listen to intact voice feedback Ford & Mathalon, 2004Ford et al, 2001;Ford et al, 2007;Heinks-Maldonado et al, 2005;HeinksMaldonado et al, 2007;Sitek et al, 2013;Timm et al, 2013). This suggests that the N1 component is also a signature of an internal predictive mechanism: When the prediction of the upcoming self-generated vocal sound is violated by the mismatching voice feedback, an error signal is generated and, as a consequence, amplitude attenuation is smaller Ford & Mathalon, 2004Ford et al, 2001;Ford et al, 2007;HeinksMaldonado et al, 2005;Heinks-Maldonado et al, 2007;Sitek et al, 2013).…”

“…During vocalization, the frontal brain regions responsible for speech production send an efference copy of the speech motor plan to auditory sensory regions Heinks-Maldonado et al, 2005;Heinks-Maldonado et al, 2007;Sitek et al, 2013). During vocal production, the incoming voice feedback is compared against the predicted sensory consequences of the speech motor plan: If they match closely, auditory cortical responsiveness is suppressed Heinks-Maldonado et al, 2005;Heinks-Maldonado et al, 2007;Houde et al, 2002;Ventura et al, 2009;Sitek et al, 2013).…”