Spoken language comprehension is one of these processes, and it is associated with certain peculiarities, as well as gaps current science has to address. The frontal lobe of the brain is regarded as the major area controlling speech production and comprehension. At that, these processes are regulated by the work of several regions of the brain, including Broca’s and Wernicke’s areas, the primary motor cortex, as well as posterior middle and posterior superior temporal gyri (Nasios et al., 2019). People need to process vast amounts of data when comprehending spoken language, including other individuals’ speech with its peculiarities external and noises (Riecke et al., 2018). For centuries, researchers have tried to understand all these specifics of human brain functioning, and modern neuroscience has offered diverse opportunities to shed light on the most obscure areas (Tremblay & Dick, 2016). This paper includes a brief analysis of the peculiarities of spoken language comprehension as explored by scientists with the use of different frameworks and methodologies.
First, it is necessary to provide brief insights into the methodology used to explore the peculiarities of spoken speech comprehension. The twentieth century became a breakthrough in the understanding of diverse mechanisms of spoken speech production and comprehension due to the development of technology, as well as an innovative experimental methodology (Rodd & Davis, 2017). Behavioral methods that have been for decades and even centuries are now facilitated by neurology-based instruments (Peelle, 2017; Willems et al., 2016). The neuropsychology approach equips scientists with knowledge regarding the various processes involved in the comprehension of spoken speech and associated distortions. A combination of brain imaging and neuropsychological tools is the current trend that is expected to lead to new discoveries and breakthroughs (Rodd & Davis, 2017). Thus, a plethora of methods and approaches employed by scientists enabled them to explore and explain the major processes related to spoken speech comprehension.
As far as the neurobiology of language is concerned, the dual-stream model is a prevailing approach in the scientific world. Scientists largely agree that two major pathways are involved, being the dorsal and ventral pathways (Lee et al., 2020). The dorsal pathway is associated with auditory-to-motor integration, while the ventral pathway is linked to lexical-semantic processing. The pathways are characterized by different anatomical functions and projections (Lee et al., 2020). The integration and collaboration between these pathways ensure proper language behavior.
The dorsal pathway includes the frontal and temporal cortex connected by arcuate and superior longitudinal fasciculus tracts (Lee et al., 2020). The central brain areas associated with this pathway are the transverse temporal gyrus, the inferior frontal gyrus (its pars opercularis), the superior temporal gyrus, the supramarginal gyrus, and planum temporale. It has been found that the frontal part of arcuate and superior longitudinal fasciculus tracts mature during early adulthood while the rest of these regions mature during late adolescent years. This pathway connects structurally temporal and premotor cortex, which leads to the processing of auditory speech signal representations into articulatory-motor representations. Brain imaging studies suggest that this pathway is already apparent in newborns, which is thought to provide “a possible neurobiological basis for the tuning process as the native phonology develops” (Lee et al., 2020, p. 2570). Researchers also explored the comprehension of syntactically complex sentences in children and found that proper comprehension occurs by seven years old (Enge et al., 2020). It is noteworthy that these neurobiological findings are similar to the results of behavioral studies.
The ventral pathway includes the inferior longitudinal fasciculus, the inferior fronto-occipital fasciculus, and the uncinate fasciculus. As for the major brain regions associated with this pathway, these are the temporal pole, the middle temporal gyrus, the inferior temporal gyrus, the pars orbitalis, and pars triangularis (Lee et al., 2020). The ventral pathway is apparent in newborns, as recent studies show (Lee et al., 2020). At that, uncinate fasciculus is developing in adulthood until the third decade of a person’s life, while the other two tracts mentioned above mature in young adulthood. As mentioned above, this pathway is related to lexical-semantic processing. Although a considerable bulk of data associated with these processes have been accumulated, researchers have little information concerning the exact role each tract plays in lexical-semantic processing.
An interesting case providing more insights into the mechanisms involved in spoken speech comprehension is linked to the processing of the so-called iconic word forms. These are words that phonologically resemble the acoustic sound they represent, such as click or beep (Peeters, 2016).. According to recent neuroimaging studies, brain areas involved in the processing of verbal and non-verbal (animal) sounds are activated when exposed to iconic words (Peeters, 2016). In simple terms, these words are a synergy of semantic units and natural sounds
The disruption of the functioning of these pathways or some of their components leads to inadequate spoken language comprehension. Brain injury is one of the central causes of distorted pathways and language disorders (Vaillant et al., 2020). This area has been explored with the focus on different types of injuries and their effects on speakers of diverse languages (Pillay et al., 2017; O’Sullivan et al., 2019). For instance, Broca’s aphasia is associated with lesions in the corresponding brain region and can also be characterized by lesions in the middle frontal and inferior gyri, basal ganglia, and white matter (Dronkers et al., 2017). Some of the common symptoms caused by this disorder include poor grammar, difficulty articulating words, difficulty with reading, or complete comprehension (Ardila et al., 2016). Wernicke’s aphasia is similar to the disorder mentioned above as the person affected by this disorder has difficulty with the production and comprehension of spoken language (Hartman et al., 2017). These health conditions are now treated, and patients spoken speech comprehension restores completely or improves considerably.
It has been found that speakers of different languages respond differently to the injury of a particular brain area (Vander Zwart et al., 2016). For instance, Turkish speakers diagnosed with Broca’s aphasia produce grammatic speech irrespective of their brain condition due to the peculiarities of the language that is highly inflected (Dronkers et al., 2017). Moreover, the damage of the areas mentioned above does not always lead to the loss of speech comprehension as the disruption is compensated by the functioning of other regions (Blanco-Elorrieta et al., 2018).
It is necessary to note that quite a strict hierarchy is associated with spoken language comprehension. According to Davis and Johnsrude (2003), this hierarchical organization is instrumental in compensating for distortion. Specific regions of the brain, as empirical studies suggest, are sensitive to intelligibility and display differentiated responses to diverse forms of distortion (Kang et al., 2017; Riecke et al., 2018). Davis and Johnsrude (2003) found that the areas responsive to distorted speech conditions were mainly found in the left hemisphere. These regions are also assumed to be related to distortion compensation. The damage of certain brain areas is also associated with some speech comprehension deficits (Wilson, 2016; Grey & van Hell, 2017). For example, lesions in dorsal pathways are mainly linked to the processing of syntax. The damage in this brain area, especially arcuate fasciculus, results in poor syntax comprehension while verbal comprehension remains undisturbed (Cheng et al., 2018). Hence, spoken speech comprehension can deteriorate due to the injury of certain regions.
However, language comprehension can remain spared even if some of the corresponding areas are damaged. One of the most prominent adaptive mechanisms is the so-called brain plasticity that encompasses the development of certain brain regions to compensate for the damage of other regions or even subsystems (White et al., 2018). Jiao et al. (2020) state that functional reorganization takes place in case of injury (or surgical procedures). The patients who underwent the surgical treatment of the inferior parietal lobe displayed substantial rapid improvement of speech processing (in case malfunctioning took place). These patients’ right hemispheric arcuate fasciculus, right hemispheric homologous areas of Wernicke’s and Broca’s regions, as well as left hemispheric inferior frontooccipital fasciculus, were recruited (Jiao et al., 2020). Duffau (2018) provides empirical evidence that networking is one of the major components of brain plasticity. The researcher states that the removal or considerable damage of Broca’s area can be compensated by the development of new networks (Duffau, 2018). Therefore, the injury of some regions of the brain or even subsystems is often compensated via several mechanisms.
In conclusion, it is necessary to note that spoken speech comprehension is an area of significant interest among neuroscientists. Diverse methods have been developed to explore the instruments and principles guiding language processing. Behaviorist and neurobiological methodologies are now often combined to examine various aspects of the problem and to dig deeper into the issue. Although numerous gaps still exist, modern scientists have identified the major regions of the brain involved in spoken speech processing. It has also been acknowledged that the injury of these areas does not necessarily lead to the loss of speech comprehension skills or their considerable deterioration. Such mechanisms as networking, re-functioning, and restructuring result in complete or partial restoration of this function.
Ardila, A., Bernal, B., & Rosselli, M. (2016). Why Broca’s area damage does not result in classical Broca’s aphasia. Frontiers in Human Neuroscience, 10, 1-3.
Blanco-Elorrieta, E., Kastner, I., Emmorey, K., & Pylkkänen, L. (2018). Shared neural correlates for building phrases in signed and spoken language. Scientific Reports, 8(1), 1-10.
Cheng, Q., Halgren, E., & Mayberry, R. (2018). Effects of early language deprivation: Mapping between brain and behavioral outcomes. In A. B. Bertolini & M. J. Kaplan (Eds.), Proceedings of the 42nd annual Boston University Conference on Language Development, (pp. 140-152). Cascadilla Press.
Davis, M. H., & Johnsrude, I. S. (2003). Hierarchical processing in spoken language comprehension. The Journal of Neuroscience, 23(8), 3423-3431.
Dronkers, N. F., Ivanova, M. V., & Baldo, J. V. (2017). What do language disorders reveal about brain–language relationships? From classic models to network approaches. Journal of the International Neuropsychological Society, 23(9-10), 741-754.
Duffau, H. (2018). The error of Broca: From the traditional localizationist concept to a connectomal anatomy of human brain. Journal of Chemical Neuroanatomy, 89, 73-81.
Enge, A., Friederici, A. D., & Skeide, M. A. (2020). A meta-analysis of fMRI studies of language comprehension in children. Neuroimage, 215, 1-11.
Grey, S., & van Hell, J. G. (2017). Foreign-accented speaker identity affects neural correlates of language comprehension. Journal of Neurolinguistics, 42, 93-108.
Hartman, K., Peluzzo, A., Shadani, S., Chellquist, I., Weprin, S., Hunt, H., Smith-Benjamin, S., & Altschuler, E. L. (2017). Devising a method to study if Wernicke’s aphasia patients are aware that they do not comprehend language or speak it understandably. Journal of Undergraduate Neuroscience Education, 16(1), E5-E12.
Jiao, Y., Lin, F., Wu, J., Li, H., Fu, W., Huo, R., Cao, Y., Wang, S., & Zhao, J. (2020). Plasticity in language cortex and white matter tracts after resection of dominant inferior parietal lobule arteriovenous malformations: A combined fMRI and DTI study. Journal of Neurosurgery, 1-8.
Kang, O., Thomson, R. I., & Moran, M. (2017). Empirical approaches to measuring the intelligibility of different varieties of English in predicting listener comprehension. Language Learning, 68(1), 115-146.
Lee, J. C., Dick, A. S., & Tomblin, J. B. (2020). Altered brain structures in the dorsal and ventral language pathways in individuals with and without developmental language disorder (DLD). Brain Imaging and Behavior, 14(6), 2569-2586.
Nasios, G., Dardiotis, E., & Messinis, L. (2019). From Broca and Wernicke to the neuromodulation era: Insights of brain language networks for neurorehabilitation. Behavioural Neurology, 2019, 1-10.
Peeters, D. (2016). Processing consequences of onomatopoeic iconicity in spoken language comprehension. In A. Papafragou, D. Grodner, D. Mirman, & J. Trueswell (Eds.), Proceedings of the 38th Annual Meeting of the Cognitive Science Society (pp. 1632-1647). Cognitive Science Society.
O’Sullivan, M., Brownsett, S., & Copland, D. (2019). Language and language disorders: Neuroscience to clinical practice. Practical Neurology, 19(5), 380-388.
Peelle, J. E. (2017). Optical neuroimaging of spoken language. Language, Cognition and Neuroscience, 32(7), 847-854.
Pillay, S. B., Binder, J. R., Humphries, C., Gross, W. L., & Book, D. S. (2017). Lesion localization of speech comprehension deficits in chronic aphasia. Neurology, 88(10), 970-975.
Riecke, L., Formisano, E., Sorger, B., Başkent, D., & Gaudrain, E. (2018). Neural entrainment to speech modulates speech intelligibility. Current Biology, 28(2), 161-169.
Rodd, J. M., & Davis, M. H. (2017). How to study spoken language understanding: A survey of neuroscientific methods. Language, Cognition and Neuroscience, 32(7), 805-817.
Tremblay, P., & Dick, A. S. (2016). Broca and Wernicke are dead, or moving past the classic model of language neurobiology. Brain and Language, 162, 60-71.
Vaillant, E., Geytenbeek, J. J. M., Jansma, E. P., Oostrom, K. J., Vermeulen, R. J., & Buizer, A. I. (2020). Factors associated with spoken language comprehension in children with cerebral palsy: A systematic review. Developmental Medicine & Child Neurology, 62(12), 1363-1373.
Vander Zwart, K. E., Geytenbeek, J. J., de Kleijn, M., Oostrom, K. J., Gorter, J. W., Hidecker, M. J. C, & Vermeulen, R. J. (2016). Reliability of the Dutch-language version of the Communication Function Classification System and its association with language comprehension and method of communication. Developmental Medicine & Child Neurology, 58(2), 180-188.
White, E. J., Nayman, C., Dunkley, B. T., Keller, A. E., Valiante, T. A., & Pang, E. W. (2018). Addressing the language binding problem with dynamic functional connectivity during meaningful spoken language comprehension. Frontiers in Psychology, 9, 1-10.
Willems, R. M., Frank, S. L., Nijhof, A. D., Hagoort, P., & van den Bosch, A. (2016). Prediction during natural language comprehension. Cerebral Cortex, 26(6), 2506-2516.
Wilson, S. M. (2016). Lesion-symptom mapping in the study of spoken language understanding. Language, Cognition and Neuroscience, 32(7), 891-899.