Speech Comprehension - Coursework Example

Speech comprehension Affiliation Speech Comprehension Speech perception relies highly on both top-down processing and bottom-up processing that are based on incoming data and previous knowledge. Bottom-up processing depends mostly on immediate auditory input while top-down processing relies mainly on an individual’s language experience (Shuai & Gong, 2014). In top-down speech perception, processing takes effect at a later stage of perception. Top-down processing advocates accept the fact that speech perception takes place simultaneously at different levels and not on a fixed occurrence. Comprehension is largely a process of hypothesis generation and testing where people need little acoustic knowledge to hypothesize on the intended message. Cauldwell and Wordell (1989) state that top-down processing is so intense in most cases that people do not hear what is being said since they often hypothesize their words. Efficient speech comprehension relies on three types of information: the listener’s linguistics and word knowledge; linguistic and communicative input; and the information from the conversation and context to a said point (Cauldwell and Wordell, 1989). This paper outlines the advantages and disadvantages of top-down processes in speech comprehension referring to the relevant cognitive research. Top-down generation of internal speech facilitates the correct identification of a speech stimulus in subsequent perception tasks (Zekveld, Heslenfeld, Festen, & Schoonhoven, 2006). This activation occurs at the part opercula of the left inferior frontal gyrus (IFG) when someone is listening to speech presented at low signal to noise ratio (SNR). When listening to intelligible speech, the bilateral temporal brain sectors in the left IFG are more activated compared to when listening to unintelligible speech. The top-down processing responds to unintelligible speech with low SNRs less than 20.95 decibel (dB). The Broca’s area is significant in both perception and production of speech and its activation results to improved speech identification (Zekveld et al. 2006). The downside with this claim is that the top-down processing cannot work alone in inferring this activation without the assistance of the bottom-up processing when the speech is not less intelligible. Top-down processing is reliable only when the speech becomes intelligible or unidentified where it serves to improve performance associated with the identification task. In their research, Zekveld et al. (2006) found out that the net variations in the compound intensity along the SNR mid-range of the categories -20.8 to -3.1 dB SNR is only 1.7 dB sound pressure level (SPL) that is too low to activate. Therapists have continually described speaking and writing as the active skills in speech perception (Crystal, 1987). In dialogue, the ability to maintain active listening comprehension is crucial and therefore people devise techniques that ensure listening is taking place. Listening is an active process that is not under a listener’s control since the pace is dictated by the speaker. Reading while compared to listening provides a more individual control. Skimming is possible with reading, but not with an active listening process. Through skimming, people check ahead and decide if they want to take part in the reading or not (Crystal, 1987). The top-down processing model is needed for a successful conversation to emerge. Among the symptoms in children with the pragmatic limitations, one is the lack of ability to maintain conversational skills. These children can speak parallel or diverge from the relevant conversational point. In managing this condition, therapists have tried the bottom-up approach that has proven non-successful. At a certain point, top-down processing therapy is used to solve pragmatic disability to improve on the nature of conversational strategies (Crystal, 1987). In teaching children to the best approach to attacking a pragmatic limitation, a simple conversational plan has to precede complex conversational methods. Top-down processing enables listeners to use prior knowledge and context to construct meaning (Yeldham and Gruba, 2014). Top-down and bottom-down processing operate harmoniously to facilitate effective listening. Top-down processing facilitates interpretation by contextualizing while guiding the incoming linguistic input, and the bottom-down processing constraints listener’s interpretation of a speaker’s utterance. The approach, however, is disadvantageous to second language learners due to the limited knowledge of the target linguistics. Language two learners experience considerable limitations with the phonological aspects of the new language (Yeldham and Gruba, 2014). Learners who lack perceptual skills relevant to the second language are led astray by top-down processing where the conversation receives a different comprehension. Tsui and Fullilove (1997) conducted studies that showed that speech perception was better foe skilled learners and readers that were able to engage in top-down processing. The study emphasized on top-down processing in discriminating the comprehension of language two learners in large-scale examinations in Hong Kong. The study identified two types of schema namely the non-matching and the matching schema. In the case of matching schema, the schema was congruent with subsequent linguistic inputs and the candidates’ use of top-down processing gave them the correct answers. In the non-matching case, schema activated by initial linguistic inputs was not congruent with the corresponding linguistic inputs and the candidates needed to revise the hypothesis accordingly to get the correct answer (Tsui and Fullilove, 1997). Izumi (2003) claims that a learner and especially in the second language has to move from the semantic processing inhibiting speech comprehension into a more syntactic approach necessary for second language development. Tsui and Fullilove (1997) conducted a study that dissociated linguistic processing in the left hemisphere. The study aimed at locating a right lateralization in non-tonal language speakers and a left lateralization in tonal language speakers during speech prosody processing. The left hemisphere advantage was attributed to top-down processing in lexical tone perception while the right hemisphere advantage is associated with the bottom-down processing. Top-down processing was seen to take root in a late time window indicating that top-down assists in vowel processing or intonation during speech perception. Shuai and Gong (2014), however, found no left hemisphere advantage in their study in tasks that involve syllables and hums that directed participants toward a right advantage and pitch contours only. The mixed outcomes reflect a multifaceted ideology on lexical tonal processing and lateralization. Since humans predict incoming signals based on speech, top-down processing becomes relevant. However, this prediction has to be matched by the bottom-up processing (Shuai and Gong 2014). When a person comprehends speech, a process occurs in the brain that must, be influenced partly by the top-down input and partly determined by the bottom-up input. Perception is achieved by the effects from the on high, such as interpretive dispositions in the perceiver due to their particular knowledge and interests. McClelland, Mirman, and Holt suggest that speech perception and mostly when the sounds are ambiguous or degraded is facilitated by the lexical ability. This facilitation is achieved through a bi-directional flow of information that allows the lexical to influence pre-lexical knowledge (McClelland et al.). A study showed that an ambiguous sound, for example, a /g/ or a /k/ has a high possibility of identification as a /k/ when followed by an ‘iss’ and higher probability of being perceived as a /g/ if followed by ‘ift’. McClelland et al. states that this is attributed to a lexical influence where prediction is reshaped mentally in regard to previous conversations. These influences are attributed to top-down processing that is influential in all levels of language processing (McClelland et al.). Shuai and Gong (2014) used Multifocal Motor Neuropathy (MMN) component to establish that top-down processing was relevant for the syntax and semantics at a pre-attentive stage. The study showed that acoustic properties or even long-term speech perception experience can induce automatic pre-attentive processing. Top-down processing acts like a predetermined process, making necessary brain regions prepare for forthcoming tasks. Through top-down processing, the lexical is prepared to accompany the process of speech perception. A memory modulation of lateralization shows that even as language experience affects automatic processing at a retentive stage, it is considerably difficult to observe top-down processing effects at the pre-attentive stage (Shuai & Gong, 2014). Lexical tonal perception, however, cannot be said to be influenced by either top-down processing or bottom-up processing. An example by Shuai and Gong (2014) shows that there are automatic attention shifts to an unexpected event that do not require active preparation beforehand and tasks related to top-down processing. Gandour et al. (2004) states that there are lots of findings against any existence of a centralized core in the left hemisphere devoted to language processing. Top-down processing overcomes the challenge posed by competing speech and competing noise. Through a research investigating speech and noise masking on language, Ezzatian (2011) examined the rate of masking release on young and old participants. The study showed that both the young and the old benefit equally in masking prior to hearing the target sentence. This benefit was attributed to top-down information processing. The analysis showed that speech perception and comprehension among the elderly in noisy environments may be due to age-related declines and can employ top-down processing to help offset them (Ezzatian, 2011). Noise pollution masks the dominant auditory source that speech perception is interrupted. If this is the case, Ezzatian (2011) states that as long as one is familiar with top-down processing they can comprehend and take part in the discussion to a satisfactory level. Speech perception, in this case, is also influenced by the level of similarity between the ongoing conversation and the disturbance. The more dissimilar the streams are, the easier the perceptual separation is and vice versa (Ezzatian, 2011). Information masking can hinder the listener from comprehending the message. With a top-down perceptual segregation of the target speech from the competing conversation, speech comprehension is possible. Top-down cues necessary for perceptual separation include knowledge of the speaker’s identity and familiarity with the talker’s voice. Other relevant methods include knowledge of the source’s location, or even prior knowledge of the topic or the target sentence (Ezzatian, 2011). The age factor creates some of the limitations of using top-down processing. This occurs because the older people experience more interference than the young. Age-related declines can severely impede older adults’ ability to perceive speech in noisy environments. Cognitive declines contribute though not substantially in the decline in auditory processing. As people get older, the peripheral auditory system like the cochlea degenerates leading to a spectral temporal resolution and degraded auditory signal representation past the cochlea (Ezzatian, 2011). A striking characteristic of human perception is the subjective experience that highly depends not only on the environmental sensory information, but also on the hypothesized expectations (Davis and Johnsrude, 2007). The influences of the top-down processing model by which prior knowledge and sensory knowledge are integrated remain a complex hypothesis to many people. Studies have indicated different outcomes regarding the means by which prior knowledge and sensory information are integrated with the brain to facilitate speech perception. The constant outcome among these studies is that a top-down approach is essential to the enhancement of speech comprehension, and its benefits exceed the limitations. Based on these findings, it can be said that top-down interactive mechanisms play an important role in explaining the perception of spoken language within auditory networks. The evidence is in support of the benefits of the top-down processing in speech comprehension. This discussion, however, indicates that top-down and bottom-up processing are distinct but complementary processes. The influence that top-down processing plays on the lexical information on lower level perpetual processes cannot be ignored. Davis and Johnsrude (2007) conducted studies that went beyond the usage of phonetically ambiguous stimuli and found out that top-down processing enhances speech perception. An interpretation of his findings is that a top-down feedback process involving a bottom-down processing approach and comparison with higher linguistic representation is responsible for speech comprehension and long lasting changes in phonetic categorization. Top-down processing does not require that information should have originated from a high-level process. Top-down processing utilizes an approach that gathers information at low levels, interprets it at a higher level, and brings it back to perceive low-level processes. The top-down benefits outdo the disadvantages as shown by numerous studies. The top-down processing approach is a valid approach that will improve on speech perception when studied and used efficiently. References Cauldwell, R. & Wordell, C. (1988). Testing listening comprehension In Japanese University Entrance Examinations. Journal of the Japan Association of Language Teachers, 10(1&2). Crystal, D. (1987). Comprehending (And Uncomprehending) Compression: From Top to Bottom And Back Again. Teaching Vocabulary. Davis, M. H. & Johnsrude I. S. (2007). Hearing Speech Sounds: Top-down influences on The Interface between audition and speech perception. Hearing research, 229 (1-2), 132-147. Ezzatian, P. (2011). Why does Speech Understanding in Noise Decline with Age? The Contribution of age-related differences in Auditory Priming, Stream Segregation, And listening in Fluctuating maskers. Graduate Department of Psychology, University of Toronto: Toronto. Izumi, S. (2003). Comprehension and Production Processes in Second Language Learning: In Search of the Psycholinguistic Rationale of the Output Hypothesis. Applied Linguistics, 24(2), 168-196. McClelland, J. L., Mirman, D. & Holt, L. L. (n.d.). Are there interactive processes in Speech Perception? TRENDS in Cognitive Sciences 10(8). Shuai, L. & Gong, T. (2014). Temporal relation between top-down and bottom-up processing in Lexical tone perception. Frontiers in Behavioral Neuroscience, 8(97). Tsui, A. B. & Fullilove, J. (1998). Bottom-up or Top-down Processing as a Discriminator of L2 Listening Performance. Applied Linguistics, 19(4), 432-451. Yeldham, M. & Gruba, P. (2013). Toward an instructional approach to developing interactive Second language listening. Language Teaching Research, 18(1), 33-53. Zekveld, A. A., Heslenfeld, D. J., Festen, J. M. & Schoonhoven, R. (2006). Top–down and Bottom–up processes in speech comprehension. NeuroImage, 32(3), 1826-1836. Read More