The Temporal Lobes Differentiate between the Voices of Famous and Unknown People: An Event-Related fMRI Study on Speaker Recognition

Abstract

It is widely accepted that the perception of human voices is supported by neural structures located along the superior temporal sulci. However, there is an ongoing discussion to what extent the activations found in fMRI studies are evoked by the vocal features themselves or are the result of phonetic processing. To show that the temporal lobes are indeed engaged in voice processing, short utterances spoken by famous and unknown people were presented to healthy young participants whose task it was to identify the familiar speakers. In two event-related fMRI experiments, the temporal lobes were found to differentiate between familiar and unfamiliar voices such that named voices elicited higher BOLD signal intensities than unfamiliar voices. Yet, the temporal cortices did not only discriminate between familiar and unfamiliar voices. Experiment 2, which required overtly spoken responses and allowed to distinguish between four familiarity grades, revealed that there was a fine-grained differentiation between all of these familiarity levels with higher familiarity being associated with larger BOLD signal amplitudes. Finally, we observed a gradual response change such that the BOLD signal differences between unfamiliar and highly familiar voices increased with the distance of an area from the transverse temporal gyri, especially towards the anterior temporal cortex and the middle temporal gyri. Therefore, the results suggest that (the anterior and non-superior portions of) the temporal lobes participate in voice-specific processing independent from phonetic components also involved in spoken speech material.

Speech-evoked brain activity is more robust to competing speech when it is spoken by someone familiar

“…The area of STS we found was most sensitive to the familiar-unfamiliar voice difference is located more posteriorally than the temporal voice areas in some of the previous studies (e.g., 31–33). Nevertheless, Bethmann, Scheich, and Brechman (35) found that the greatest difference between familiar and unfamiliar voices occurred in both anterior and posterior areas that were more distant from primary auditory cortex, which is consistent with our results. In addition, Warren et al (36) proposed that abstraction of voice identity information occurs in posterior STS, and subsequent analysis occurs in anterior parts of STS and MTG.…”

“…Birkett et al (37) found greater activity for familiar than unfamiliar voices in the left MTG. However, all of these studies either used tasks that asked participants to judge voice familiarity (35, 37) or had participants passively listen to stimuli while speaker identity varied across conditions (36)—whereas the task in the current study was to report the words that were spoken.…”

The processing of voice identity in developmental prosopagnosia

“…Investigators noting normal activation of the fusiform face area in developmental prosopagnosia (Avidan et al, 2005; Avidan et al, 2009) have performed morphometric studies reporting abnormalities in anterior fusiform cortex and the anterior and middle temporal lobes (Behrmann et al, 2007). Functional neuroimaging has revealed temporal voice areas in the middle and anterior superior temporal sulcus, more so on the right (Belin et al, 2000), which show sensitivity to voice identity in adaptation studies (Belin et al, 2003; Warren et al, 2006) and activity correlations with the familiarity of voices (Bethmann et al, 2012). It must be noted, though, that the anterior temporal regions responding to facial identity are more ventral than temporal voice areas (Belin et al, 2000) and do not overlap (Joassin et al, 2011).…”

The Crux of Voice (In)Security: A Brain Study of Speaker Legitimacy Detection

“…There are some neuroscience studies on voice recognition (e.g., [3], [6], [7], [20]). Belin et al [6] studied the brain areas involved in voice recognition.…”