**2.2 Studies on age related noise effects**

As age effects, sensitivity to the high frequencies is lost first and the loss is irreversible. In audiometry, such loss is described as a permanent threshold shift. Audiometric testing consists of determination of the minimum intensity (the threshold) at which a person can detect sound at a particular frequency. As sensitivity to particular frequencies is lost as a result of age or damage, the intensity at which a stimulus can be detected increases. It is in this sense that hearing loss can be described as a threshold shift. Studies have shown age decrements in performance of sustained attention tasks.

Parasuranam, et al. (1990) [6] Thirty-six young (19-27 years), middle-aged (40-55 years), and old (70-80 years) adults performed a 30-min vigilance task at low (15 per min) and high (40 per min) event rates for 20 sessions. Skill-acquisition curves modeled on power, hyperbolic, and exponential functions were predicted. With extensive practice, hit rates increased and false-alarm rates decreased to virtually asymptotic levels. Skill development was best described by the hyperbolic function. Practice reduced but did not eliminate the vigilance decrement in all subjects. The event-rate effect-the decrease in hit rate at high event rates-was reduced with practice and eliminated in young subjects. Hit rates decreased and false-alarm rates increased with age, but there was little attenuation of age differences with practice. Implications for theories of vigilance, skill development, and cognitive aging are discussed.

Hale (1990) [7] Children respond more slowly than young adults on a variety of information-processing tasks. The global trend hypothesis posits that processing speed changes as a function of age, and that all component processes change at the same rate. A unique prediction of this hypothesis is that the overall response latencies of children of a particular age should be predictable from the latencies of young adults performing the same tasks-without regard to the specific componential makeup of the task. The current effort tested this prediction by examining the performance of 4 age groups (10-, 12-, 15-, and 19 year-olds) on 4 different tasks (choice reaction time, letter matching, mental rotation, and abstract matching). An analysis that simultaneously examined performance on all 4 tasks provided strong support for the global trend hypothesis. By plotting each child group's performance on all 4 tasks as a function of the young adult group's performance in the corresponding task conditions, precise linear functions were revealed: 10-year-olds were approximately 1.8 times slower than young adults on all tasks, and 12-year-olds were approximately 1.5 times slower, whereas 15-year-olds appeared to process information as fast as young adults.

Madden (1992) [8] Examined in three experiments a revised version of the Eriksen and Yeh (C. W. Eriksen and Y.-Y. Yeh, 1985) model of attentional allocation during visual search. Results confirmed the assumption of the model that performance represents a weighted combination of focused-and distributed-attention trials, although they were relied on focused attention more than was predicted. Consistent with the model, predictions on the basis of the assumption of a terminating search fit the data better than predictions on the

indicated to be a causal result of the combined, and uncorrelated, effect of cognitive demands and quality of work attributes experienced by workers. This causal relationship was found to be dependent on the context of, but not necessarily the time exposed to, the

As age effects, sensitivity to the high frequencies is lost first and the loss is irreversible. In audiometry, such loss is described as a permanent threshold shift. Audiometric testing consists of determination of the minimum intensity (the threshold) at which a person can detect sound at a particular frequency. As sensitivity to particular frequencies is lost as a result of age or damage, the intensity at which a stimulus can be detected increases. It is in this sense that hearing loss can be described as a threshold shift. Studies have shown age

Parasuranam, et al. (1990) [6] Thirty-six young (19-27 years), middle-aged (40-55 years), and old (70-80 years) adults performed a 30-min vigilance task at low (15 per min) and high (40 per min) event rates for 20 sessions. Skill-acquisition curves modeled on power, hyperbolic, and exponential functions were predicted. With extensive practice, hit rates increased and false-alarm rates decreased to virtually asymptotic levels. Skill development was best described by the hyperbolic function. Practice reduced but did not eliminate the vigilance decrement in all subjects. The event-rate effect-the decrease in hit rate at high event rates-was reduced with practice and eliminated in young subjects. Hit rates decreased and false-alarm rates increased with age, but there was little attenuation of age differences with practice. Implications for theories of vigilance, skill development,

Hale (1990) [7] Children respond more slowly than young adults on a variety of information-processing tasks. The global trend hypothesis posits that processing speed changes as a function of age, and that all component processes change at the same rate. A unique prediction of this hypothesis is that the overall response latencies of children of a particular age should be predictable from the latencies of young adults performing the same tasks-without regard to the specific componential makeup of the task. The current effort tested this prediction by examining the performance of 4 age groups (10-, 12-, 15-, and 19 year-olds) on 4 different tasks (choice reaction time, letter matching, mental rotation, and abstract matching). An analysis that simultaneously examined performance on all 4 tasks provided strong support for the global trend hypothesis. By plotting each child group's performance on all 4 tasks as a function of the young adult group's performance in the corresponding task conditions, precise linear functions were revealed: 10-year-olds were approximately 1.8 times slower than young adults on all tasks, and 12-year-olds were approximately 1.5 times slower, whereas 15-year-olds appeared to process information as

Madden (1992) [8] Examined in three experiments a revised version of the Eriksen and Yeh (C. W. Eriksen and Y.-Y. Yeh, 1985) model of attentional allocation during visual search. Results confirmed the assumption of the model that performance represents a weighted combination of focused-and distributed-attention trials, although they were relied on focused attention more than was predicted. Consistent with the model, predictions on the basis of the assumption of a terminating search fit the data better than predictions on the

particular task the operator was involved with.

decrements in performance of sustained attention tasks.

**2.2 Studies on age related noise effects** 

and cognitive aging are discussed.

fast as young adults.

basis of an exhaustive search. The effects of varying cue validity favored an interpretation of focused attention in terms of a processing gradient rather than a zoom lens. Although the allocation of attention across trials was similar for young and older adults, there was an agerelated increase in the time required to allocate attention within individual trials.

Carayon, et al. (2000) [9] There have been several recent reports on the potential risk to hearing from various types of social noise exposure. However, there are few populationbased data to substantiate a case for concern. During the last 10-20 years use of personal cassette players (PCPs) has become very much more prevalent, and sound levels in public nightclubs and discotheques are reported to have increased. This study investigated the prevalence and types of significant social noise exposure in a representative population sample of 356 18-25 year olds in Nottingham. Subjects were interviewed in detail about all types of lifetime noise exposure. Noise measurements were also made for both nightclubs and PCPs. In the present sample, 18.8% of young adults had been exposed to significant noise from social activities, compared with 3.5% from occupational noise and 2.9% from gunfire noise. This indicates that social noise exposure has tripled since the early 1980s in the UK. Most of the present day exposure, measured in terms of sound energy, comes from nightclubs rather than PCPs. Moreover, 66% of subjects attending nightclubs or rock concerts reported temporary effects on their hearing or tinnitus. As will be reported in a later publication, any persistent effect of significant noise exposure on 18-25 year olds is difficult to show, however these data suggest that further work is indicated to study the possibility of sub-clinical damage, and also to consider the implications for employees of nightclubs.

Boman, et al. (2005) [10] The objectives in this paper were to analyze noise effects on episodic and semantic memory performance in different age groups, and to see whether age interacted with noise in their effects on memory. Data were taken from three separate previous experiments that were performed with the same design, procedure and dependent measures with participants from four age groups (13-14, 18-20, 35-45 and 55-65 years). Participants were randomly assigned to one of three conditions: (a) meaningful irrelevant speech, (b) road traffic noise, and (c) quiet. The results showed effects of both noise sources on a majority of the dependent measures, both when taken alone and aggregated according to the nature of the material to be memorized. However, the noise effects for episodic memory tasks were stronger than for semantic memory tasks. Further, in the reading comprehension task, cued recall and recognition were more impaired by meaningful irrelevant speech than by road traffic noise. Contrary to predictions, there was no interaction between noise and age group, indicating that the obtained noise effects were not related to the capacity to perform the task. The results from the three experiments taken together throw more light on the relative effects of road traffic noise and meaningful irrelevant speech on memory performance in different age groups.

#### **2.3 Studies on noise effects related to task performance**

Suter (1991) [11] The effects of noise are seldom catastrophic, and are often only transitory, but adverse effects can be cumulative with prolonged or repeated exposure. Although it often causes discomfort and sometimes pain, noise does not cause ears to bleed and noiseinduced hearing loss usually takes years to develop. Noise-induced hearing loss can indeed impair the quality of life, through a reduction in the ability to hear important sounds and to

Some Studies on Noise and Its Effects on Industrial/Cognitive Task Performance and Modeling 177

that the lack of "helping behavior" that was noted under experimental noise exposure may

Birgitta, et al. (1999) [16] Exposure to night-time noise also induces secondary effects, or socalled after effects. These are effects that can be measured the day following the night-time exposure, while the individual is awake. The secondary effects include reduced perceived sleep quality; increased fatigue; depressed mood or well-being; and decreased performance. Stansfeld (2000) [17] Noise, including noise from transport, industry, and neighbors, is a prominent feature of the urban environment. This paper reviews the effects of environmental noise on the non-auditory aspects of health in urban settings. Exposure to transport noise disturbs sleep in the laboratory, but generally not in field studies, where adaptation occurs. Noise interferes with complex task performance, modifies social behavior, and causes annoyance. Studies of occupational noise exposure suggest an association with hypertension, whereas community studies show only weak relations between noise and cardiovascular disease. Aircraft and road-traffic noise exposure are associated with psychological symptoms and with the use of psychotropic medication, but not with the onset of clinically defined psychiatric disorders. In carefully controlled studies, noise exposure does not seem to be related to low birth weight or to congenital birth defects. In both industrial studies and community studies, noise exposure is related to increased catecholamine secretion. In children, chronic aircraft noise exposure impairs reading comprehension and long-term memory and may be associated with increased blood pressure. Noise from neighbors causes annoyance and sleep and activity interference health effects have been little studied. Further research is needed for examining coping strategies

WHO (2002) [18] It has been documented in both laboratory subjects and in workers exposed to occupational noise, that noise adversely affects cognitive task performance. In children, too, environmental noise impairs a number of cognitive and motivational

Harris, et al. (2005) [19] Studies from our lab show that noise exposure initiates cell death by multiple pathways, therefore, protection against noise may be most effective with a multifaceted approach. The Src protein tyrosine kinase (PTK) signaling cascade may be involved in both metabolic and mechanically induced initiation of apoptosis in sensory cells of the cochlea. The current study compares three Src-PTK inhibitors, KX1-004, KX1-005 and KX1-174 as potential protective drugs for NIHL. Chinchillas were used as subjects. A 30 microl drop of one of the Src inhibitors was placed on the round window membrane of the anesthetized chinchilla; the vehicle (DMSO and buffered saline) alone was placed on the other ear. After the drug application, the middle ear was sutured and the subjects were exposed to noise. Hearing was measured before and several times after the noise exposure and treatment using evoked responses. At 20 days post-exposure, the animals were anesthetized their cochleae extracted and cochleograms were constructed. All three Src inhibitors provided protection from a 4 h, 4 kHz octave band noise at 106 dB. The most effective drug, KX1-004 was further evaluated by repeating the exposure with different doses, as well as, substituting an impulse noise exposure. For all conditions, the results suggest a role for Src-PTK activation in noise-induced hearing loss (NIHL), and that therapeutic intervention with a Src-PTK inhibitor may offer a novel approach in the

be related to inattention to incidental cues.

and the possible health consequences of adaptation to noise.

parameters.

treatment of NIHL.

communicate with family and friends. Some of the other effects of noise, such as sleep disruption, the masking of speech and television, and the inability to enjoy one's property or leisure time also impair the quality of life. In addition, noise can interfere with the teaching and learning process, disrupt the performance of certain tasks, and increase the incidence of antisocial behavior.

Evans, et al. (1993) [12] Large numbers of children both in the United States and throughout the economically developing world are chronically exposed to high levels of ambient noise. Although a great deal is known about chronic noise exposures and hearing damage, much less is known about the non-auditory effects of chronic ambient noise exposure on children, to estimate the risk of ambient noise exposure to healthy human development, more information. About and attention to non-auditory effects such as psycho-physiological functioning, motivation, and cognitive processes is needed. This article critically reviews existing research on the non-auditory effects of noise on children; develops several preliminary models of how noise may adversely affect children; and advocates an ecological perspective for a future research agenda.

Evans, et al. (1997) [13] In the short term, noise induced arousal, may produce better performance of simple tasks, but cognitive performance deteriorates substantially for more complex tasks (i.e. tasks that require sustained attention to details or to multiple cues; or tasks that demand a large capacity of working memory, such as complex analytical processes). Some of the effects are related to loss in auditory Comprehension and language acquisition, but others are not, among the cognitive effects, reading, attention, problem solving and memory are most strongly affected by noise. The observed effects on motivation, as measured by persistence with a difficult cognitive task, may either be independent or secondary to the aforementioned cognitive impairments. For aircraft noise, the most important effects are interference with rest, recreation and watching television. This is in contrast to road traffic noise, where sleep disturbance is the predominant effect. The primary sleep disturbance effects are: difficulty in falling asleep (increased sleep latency time); awakenings; and alterations of sleep stages or depth, especially a reduction in the proportion of REM-sleep (REM = rapid eye movement). Other primary physiological effects can also be induced by noise during sleep, including Noise sources 7 increased blood pressure; increased heart rate; increased finger pulse amplitude; vasoconstriction; changes in respiration; cardiac arrhythmia; and an increase in body movements.

Smith (1998) [14] This paper examines the operation of urban bus transport systems based upon exclusive bus roadways (bus ways) in three cities in Brazil. The historic, economic, political, regulatory and operating context for these services is discussed. The strengths and weaknesses of bus way systems in Curitiba, Porto Allegre and São Paulo are compared, with particular reference to the operating capacity of the bus ways. The paper concludes with an assessment of the importance of operations techniques, infrastructure development, land use planning, political stability and regulation to the success or failure of these systems.

Berglund, et al. (1999) [15] Two types of memory deficits have been identified under experimental noise exposure: incidental memory and memory for materials that the observer was not explicitly instructed to focus on during a learning phase. For example, when presenting semantic information to subjects in the presence of noise, recall of the information content was unaffected, but the subjects were significantly less able to recall, for example, in which corner of the slide a word had been located. There is also some evidence

communicate with family and friends. Some of the other effects of noise, such as sleep disruption, the masking of speech and television, and the inability to enjoy one's property or leisure time also impair the quality of life. In addition, noise can interfere with the teaching and learning process, disrupt the performance of certain tasks, and increase the incidence of

Evans, et al. (1993) [12] Large numbers of children both in the United States and throughout the economically developing world are chronically exposed to high levels of ambient noise. Although a great deal is known about chronic noise exposures and hearing damage, much less is known about the non-auditory effects of chronic ambient noise exposure on children, to estimate the risk of ambient noise exposure to healthy human development, more information. About and attention to non-auditory effects such as psycho-physiological functioning, motivation, and cognitive processes is needed. This article critically reviews existing research on the non-auditory effects of noise on children; develops several preliminary models of how noise may adversely affect children; and advocates an ecological

Evans, et al. (1997) [13] In the short term, noise induced arousal, may produce better performance of simple tasks, but cognitive performance deteriorates substantially for more complex tasks (i.e. tasks that require sustained attention to details or to multiple cues; or tasks that demand a large capacity of working memory, such as complex analytical processes). Some of the effects are related to loss in auditory Comprehension and language acquisition, but others are not, among the cognitive effects, reading, attention, problem solving and memory are most strongly affected by noise. The observed effects on motivation, as measured by persistence with a difficult cognitive task, may either be independent or secondary to the aforementioned cognitive impairments. For aircraft noise, the most important effects are interference with rest, recreation and watching television. This is in contrast to road traffic noise, where sleep disturbance is the predominant effect. The primary sleep disturbance effects are: difficulty in falling asleep (increased sleep latency time); awakenings; and alterations of sleep stages or depth, especially a reduction in the proportion of REM-sleep (REM = rapid eye movement). Other primary physiological effects can also be induced by noise during sleep, including Noise sources 7 increased blood pressure; increased heart rate; increased finger pulse amplitude; vasoconstriction; changes

Smith (1998) [14] This paper examines the operation of urban bus transport systems based upon exclusive bus roadways (bus ways) in three cities in Brazil. The historic, economic, political, regulatory and operating context for these services is discussed. The strengths and weaknesses of bus way systems in Curitiba, Porto Allegre and São Paulo are compared, with particular reference to the operating capacity of the bus ways. The paper concludes with an assessment of the importance of operations techniques, infrastructure development, land use planning, political stability and regulation to the success or failure of these systems.

Berglund, et al. (1999) [15] Two types of memory deficits have been identified under experimental noise exposure: incidental memory and memory for materials that the observer was not explicitly instructed to focus on during a learning phase. For example, when presenting semantic information to subjects in the presence of noise, recall of the information content was unaffected, but the subjects were significantly less able to recall, for example, in which corner of the slide a word had been located. There is also some evidence

in respiration; cardiac arrhythmia; and an increase in body movements.

antisocial behavior.

perspective for a future research agenda.

that the lack of "helping behavior" that was noted under experimental noise exposure may be related to inattention to incidental cues.

Birgitta, et al. (1999) [16] Exposure to night-time noise also induces secondary effects, or socalled after effects. These are effects that can be measured the day following the night-time exposure, while the individual is awake. The secondary effects include reduced perceived sleep quality; increased fatigue; depressed mood or well-being; and decreased performance.

Stansfeld (2000) [17] Noise, including noise from transport, industry, and neighbors, is a prominent feature of the urban environment. This paper reviews the effects of environmental noise on the non-auditory aspects of health in urban settings. Exposure to transport noise disturbs sleep in the laboratory, but generally not in field studies, where adaptation occurs. Noise interferes with complex task performance, modifies social behavior, and causes annoyance. Studies of occupational noise exposure suggest an association with hypertension, whereas community studies show only weak relations between noise and cardiovascular disease. Aircraft and road-traffic noise exposure are associated with psychological symptoms and with the use of psychotropic medication, but not with the onset of clinically defined psychiatric disorders. In carefully controlled studies, noise exposure does not seem to be related to low birth weight or to congenital birth defects. In both industrial studies and community studies, noise exposure is related to increased catecholamine secretion. In children, chronic aircraft noise exposure impairs reading comprehension and long-term memory and may be associated with increased blood pressure. Noise from neighbors causes annoyance and sleep and activity interference health effects have been little studied. Further research is needed for examining coping strategies and the possible health consequences of adaptation to noise.

WHO (2002) [18] It has been documented in both laboratory subjects and in workers exposed to occupational noise, that noise adversely affects cognitive task performance. In children, too, environmental noise impairs a number of cognitive and motivational parameters.

Harris, et al. (2005) [19] Studies from our lab show that noise exposure initiates cell death by multiple pathways, therefore, protection against noise may be most effective with a multifaceted approach. The Src protein tyrosine kinase (PTK) signaling cascade may be involved in both metabolic and mechanically induced initiation of apoptosis in sensory cells of the cochlea. The current study compares three Src-PTK inhibitors, KX1-004, KX1-005 and KX1-174 as potential protective drugs for NIHL. Chinchillas were used as subjects. A 30 microl drop of one of the Src inhibitors was placed on the round window membrane of the anesthetized chinchilla; the vehicle (DMSO and buffered saline) alone was placed on the other ear. After the drug application, the middle ear was sutured and the subjects were exposed to noise. Hearing was measured before and several times after the noise exposure and treatment using evoked responses. At 20 days post-exposure, the animals were anesthetized their cochleae extracted and cochleograms were constructed. All three Src inhibitors provided protection from a 4 h, 4 kHz octave band noise at 106 dB. The most effective drug, KX1-004 was further evaluated by repeating the exposure with different doses, as well as, substituting an impulse noise exposure. For all conditions, the results suggest a role for Src-PTK activation in noise-induced hearing loss (NIHL), and that therapeutic intervention with a Src-PTK inhibitor may offer a novel approach in the treatment of NIHL.

Some Studies on Noise and Its Effects on Industrial/Cognitive Task Performance and Modeling 179

These rules were determined by taking into consideration formal standards, experiences of specialists and the measurements patterns. They were found that the model was compared with various statistics (correlation coefficients, max-min, standard deviation, average and coefficient of skewers) and error modes (root mean square Error and relative error). The correlation coefficients were significantly high, error modes were quite low and the other

Zaheeruddin, et al. (2008) [24] They developed an expert system using fuzzy approach to investigate the effects of noise pollution on speech interference. The speech interference measured in terms of speech intelligibility is considered to be a function of noise level, distance between speaker and listener, and the age of the listener. The main source of model development is the reports of World Health Organization (WHO) and field surveys conducted by various researchers. It is implemented on Fuzzy Logic Toolbox of MATLAB using both Mamdani and Sugeno techniques. They were found his result from fuzzy logic model & comparison of the results from World Health Organization (WHO) and U.S. Environmental Protection Agency (EPA). After comparison they were concluded that the model has been implemented on Fuzzy Logic Toolbox of MATLAB the results obtained from the proposed model are in good agreement with the findings of field surveys conducted in different parts of the world. The present effort also establishes the usefulness of the Fuzzy technique in studying the environmental problems where the cause-effect

Mamdani, et al. (1975) [25] Studied after an experiment on the "linguistic" synthesis of a controller for a model industrial plant (a steam engine). Fuzzy logic is used to convert heuristic control rules stated by a human operator into an automatic control strategy. They developed 24 rules for controlling stem engine. The experiment was initiated to investigate the possibility of human interaction with a learning controller. However, the control strategy set up linguistically proved to be far better than expected in its own right, and the basic experiment of linguistic control synthesis in a non-learning controller is reported here. Ross (2009) [26] Presented their approach to introduce some applications of fuzzy logic, introduced the basic concept of fuzziness and distinguish uncertainty from other form of uncertainty. It also introduce the fundamental idea of set membership, thereby laying the foundation for all material that follows, and presents membership functions as the format used from expressing set membership. Chapters discussed the fuzzification of scalar and the deffuzification of membership functions & various forms of the implication operation and

Nanthavanij, et al. (1999) [27] Developed noise contours by two procedures: 1) Analytical and 2) Graphical. The graphical procedure requires input data: ambient noise level, noise levels generated by individual machines, and the (x, y) coordinates of the machine locations. When draw the noise contours in work shop floor, a set of mathematical formulae is also developed to estimate the combined noise levels at predetermined locations (or points) of the workplace floor. Contour lines are then drawn to connect points having an equal noise level. The analytical nature of the procedure also enables engineers to quickly construct the noise contour map and revise the map when changes occur in noise levels due to a

statistics were very close to the data.

relationships are inherently fuzzy in nature.

the composition operation provided.

workplace re-layout or an addition of a new noise source.

**2.5 Studies on the noise survey** 
