Age variation in the upper limit of hearing

With a little help from my friends: adopting a P-E fit perspective in understanding the value of organizational learning climate for sustainable employability

Purpose

The objective of our study was to investigate how organizational learning climate (measured as developmental opportunities and team support for learning), career commitment, and age are related to employees' self-perceived employability, vitality and work ability (e.g., their sustainable employability). Our study adopted a P-E fit perspective building upon the notion that sustainable employability is a function of both the person (P) and the environment (E) and tests a three-way interaction between organizational learning climate, career commitment, and age.

Design

In total, 211 members of the support staff of a Dutch university completed a survey. Hierarchical stepwise regression analysis was used to analyze the data.

Findings

Only one of the two dimensions of organizational learning climate that we measured, namely the developmental opportunities, appeared to be associated with all indicators of sustainable employability. Career commitment only had a direct positive relationship with vitality. Age was negatively related to self-perceived employability and to work ability, but not to vitality. The relationship between developmental opportunities and vitality was negatively influenced by career commitment (a negative two-way interaction effect), while a positive three-way interaction effect was found between career commitment, age, and development opportunities, and with self-perceived employability as the outcome.

Theoretical and practical implications

Our findings confirmed the relevance of adopting a P-E fit perspective on sustainable employability, and of considering the possible role of age in this. It requires more detailed analyses in future research to unravel the role of age in the shared responsibility for sustainable employability. In practice, the results of our study imply that organizations should provide all employees with a working context that facilitates learning, however, with a special focus on older employees, for whom it is a particular challenge to protect their sustainable employability, possibly due to age-related stereotyping.

Originality

Our study adopted a P-E fit perspective on sustainable employability and examined the association between organizational learning climate and all three components of sustainable employability: self-perceived employability, vitality and work ability. Moreover, it investigated whether and how the employee's career commitment and age influence this relationship.

Results of Preliminary Studies on the Perception of the Relationships between Objects Presented in a Cartesian Space

Visualizations often use the paradigm of a Cartesian space for the presentation of objects and information. Unified Modeling Language (UML) is a visual language used to describe relationships in processes and systems and is heavily used in computer science and software engineering. Visualizations are a powerful development tool, but are not necessarily accessible to all users, as individuals may differ in their level of visual ability or perceptual biases. Sonfication methods can be used to supplement or, in some cases, replace visual models. This paper describes two studies created to determine the ability of users to perceive relationships between objects in a Cartesian space when presented in a sonified form. Results from this study will be used to guide the creation of sonified UML software.

Ergonomics/Human factors needs of an ageing workforce in the manufacturing sector

BACKGROUND

As the effects of demographic transition are realised around the world, many in-dustrial societies are facing the effects of a baby boom generation, increased life expectancies, decreased birth rates and recent changes to retirement legislation with the result that older work¬ers are set to comprise a greater proportion of the labour force.

METHODS

This paper reviews the evidence for the physical and cognitive factors that characterise an ageing workforce in manufacturing. From an ergonomics and human factors (E/HF) pers¬pective, characteristics of manufacturing tasks and the effects of ageing provide an insight into how the industry will have to adapt to support the user needs of the older worker in the future. The approach taken is drawn from Ilmarinen's framework of age, experience, and work performance, from which specific E/HF issues are explored.

RESULTS

There would appear to potential to support physical decline in older workers within manufacturing jobs through increased mechanisation and automation; however, those factors associated with cognitive human factors are less clear. Increased mechanisation and automation can place greater loads and demands on the older worker where cognitive decline is more subtle and varied between workers.

CONCLUSION

Using historical and contemporary findings and the relationship between age, experience, and work performance is redrawn to include both cognitive skills and physical attributes to provide recommendations for future job design and worker needs.

Effects of Piezosurgery on the cochlear outer hair cells

CONCLUSIONS

The absence of audiologic side effects highlights the reduced trauma of the piezoelectric cut, demonstrates the superiority of the Piezosurgery device in terms of safety and protection of anatomical structures and confirms its applicability in all the otologic techniques tested.

OBJECTIVES

The aim of the present study was to estimate the effect of Piezosurgery on the cochlea and in particular on the cochlear outer hair cells.

PATIENTS AND METHODS

We selected 60 patients with a history of otologic surgery with Piezosurgery. Before and 6 months after surgery, all the patients underwent the following instrumental examinations: pure-tone audiometry, tympanometry, transient evoked otoacoustic emissions (TEOAEs), distortion product otoacoustic emissions (DPOAEs) and auditory brainstem response (ABR).

RESULTS

Piezosurgery showed its safety on the inner ear and in particular on the cochlear outer hair cells: for each instrumental examination (pure-tone audiometry, tympanometry, TEOAE, DPOAEs and ABR), no patients presented postoperative worsening.

Piezosurgery in otologic surgery: Four years of experience

Objectives: Piezosurgery (Mectron Medical Technology, Genoa, Italy) is a new ultrasound instrument (24.7-29.5 kHz) that is able to cut the bone without necrosis and nonmineralized tissues damage. The aim of this work has been to report our experience with the piezoelectric device in otologic surgery.

Study Design: We have used the piezoelectric device in 50 patients affected by otosclerosis, 50 by chronic otitis media, 20 by posttraumatic facial nerve palsy, 10 by type A glomus tympanicum tumor, and in three patients with a B-cell non-Hodgkin lymphoma.

Subjects and Methods: Patients underwent platinotomy, mastoidectomy, antroatticotomy, posterior tympanotomy, facial nerve decompression, and excision of middle ear tumors. Before and 6 months after surgery, all the patients underwent the following instrumental examinations: pure-tone audiometry, tympanometry, transient-evoked otoacoustic emissions, distortion product otoacoustic emissions, auditory brainstem response, and electronystamographic recording.

Results: In each surgical technique, the piezoelectric device provided excellent control without side effects on the adjacent structures of the middle and inner ear.

Conclusions: The piezoelectric device is a new and revolutionary bony scalpel using the microvibrations at ultrasonic frequency so that soft tissue will not be damaged even on accidental contact with the cutting tip; this renders the piezoelectric device ideal for otologic bone surgery.

The ototoxicity of styrene: a review of occupational investigations

OBJECTIVES

The objective of this study was to review critically a number of occupational investigations of the exposure and effect relation between inhaled styrene vapour and hearing loss. There is concern that workers' hearing may be impaired by exposure to styrene, as used in industries making plastics and fibreglass-reinforced products.

METHODS

Seven occupational studies, each dealing with the ototoxicity of styrene, were examined. Factors assessed included the experimental design and number of subjects within exposure groups, measurement of the styrene-in-air concentration, confirmation of the styrene exposure by blood or urine analysis, determination of the hearing threshold levels for the exposure and control groups, and measurement of any occupational noise in the subjects' workplaces. Consideration was also given to statistical relations between high-frequency hearing loss and lifetime exposure indices for styrene and noise.

RESULTS

The results are equivocal. Four investigations failed to find any effect of styrene on hearing thresholds. In contrast, other investigations claimed to have demonstrated styrene-induced hearing loss in industrial populations, with synergism between styrene and noise. However, these reports exhibited shortcomings of experimental design and data analysis.

CONCLUSIONS

Considering the body of evidence as a whole, hearing deficits due to occupational exposure to styrene at low concentrations have not been demonstrated by scientifically reliable argument. There is some suggestion of an association between styrene exposure, occupational noise, and hearing dysfunction. Further studies in humans are necessary to clarify this question.

Plastic changes in the central auditory system after hearing loss, restoration of function, and during learning

Traditionally the auditory system was considered a hard-wired sensory system; this view has been challenged in recent years in light of the plasticity of other sensory systems, particularly the visual and somatosensory systems. Practical experience in clinical audiology together with the use of prosthetic devices, such as cochlear implants, contributed significantly to the present view on the plasticity of the central auditory system, which was originally based on data obtained in animal experiments. The loss of auditory receptors, the hair cells, results in profound changes in the structure and function of the central auditory system, typically demonstrated by a reorganization of the projection maps in the auditory cortex. These plastic changes occur not only as a consequence of mechanical lesions of the cochlea or biochemical lesions of the hair cells by ototoxic drugs, but also as a consequence of the loss of hair cells in connection with aging or noise exposure. In light of the aging world population and the increasing amount of noise in the modern world, understanding the plasticity of the central auditory system has its practical consequences and urgency. In most of these situations, a common denominator of central plastic changes is a deterioration of inhibition in the subcortical auditory nuclei and the auditory cortex. In addition to the processes that are elicited by decreased or lost receptor function, the function of nerve cells in the adult central auditory system may dynamically change in the process of learning. A better understanding of the plastic changes in the central auditory system after sensory deafferentation, sensory stimulation, and learning may contribute significantly to improvement in the rehabilitation of damaged or lost auditory function and consequently to improved speech processing and production.

Monitoring noise susceptibility: sensitivity of otoacoustic emissions and subjective audiometry

The capacity of different audiological methods to detect a high noise susceptibility was examined in 20 normally hearing and 26 especially noise-susceptible subjects. The latter were selected from 422 soldiers in field studies: they had shown a temporary threshold shift (TTS) in pure tone audiometry (PTA) after regular training with firearms. In laboratory experiments, the TTS-positive soldiers were re-examined using greatly reduced sound intensities, which caused no TTS in a control subject group. Before and after acoustic stimulation, different subjective (PTA, high frequency audiometry (HFA), upper limit of hearing (ULH)) and objective (transiently evoked otoacoustic emissions (TEOAE), distortion products (DPOAE)) audiological tests were performed. After exposure to low impact noise in the laboratory, in both PTA and HFA, a TTS was observed in 11.5% (N = 3) of the noise-susceptible group (compared to 0% in the control group). In the TTS-positive group, deterioration of the ULH occurred in 28% (N = 7) (compared to 15% (N = 3) in the control group). An ULH improvement occurred in only one subject (3.8%) (compared to 25% (N = 5) in the control group). Significant alterations of click-evoked OAE-amplitudes were found in 26.9% (N = 7) of the selected groups, whereas stable emissions were observed in all but one subject (5%) of the control group. However, DPOAE alterations were seen in 19.2% (N = 5) of the TTS-positive soldiers but also in 25% (N = 5) of the control group. These results suggest that TEOAE provides a more sensitive and more objective method of detecting a subtle noise-induced disturbance of cochlear function than do PTA or DPOAE.

Evaluation of organic solvent ototoxicity by the upper limit of hearing

To clarify the effects of organic solvents on hearing, we measured the upper limit of hearing in 93 male workers exposed to organic solvents in 7 factories that produced plastic buttons or baths. Medical examinations, environmental monitoring (i.e., concentration in breathing-zone air), and biological monitoring (i.e., concentration in urine) of the organic solvents were also done. Although the organic solvent concentrations in the environmental monitoring were lower than the occupational exposure limit, the upper limit of hearing was reduced in workers who were exposed for 5 y or more. This reduction was dose-dependent and was related to styrene concentrations in breathing-zone air and mandelic acid concentrations in urine. Even individuals who had normal medical examinations showed a reduced upper limit of hearing. The upper limit of hearing may serve as an early detection indicator of health effects in workers constantly exposed to styrene.

Hearing impairment among young Chinese in a rural area

To evaluate hearing levels in Chinese young people, audiometry was carried out at a rural village in Shandong Prefecture. The subjects were 282 healthy school children and students ranging in age from 7-17 y. All subjects were asked to complete a brief questionnaire on otological symptoms, personal histories and use of noisy playthings. Audiometric threshold testing was performed at the audiometric frequencies of 0.5, 1, 2, 4 and 8 kHz. Cluster analysis was used to estimate the associations between questions in the questionnaire and hearing impairment. Fifty-six subjects (20% subjects) were excluded from the normal groups. Twenty-two ears of the excluded subjects showed 4 kHz-dip and 38 ears showed high frequency hearing loss. An increased prevalence of hearing impairment was found when compared with young Japanese (1% from the nationwide school health survey) and with young Chinese in Shandong Prefecture (0.5%). In the questionnaire, 4 questions on dizziness, head trauma, aminoglycoside administration, and suspicion of Meniere's syndrome, were included in the cluster of hearing impairment. The cause of this hearing impairment was proposed to be the potentiating effects of aminoglycoside antibiotics and exposure to noise.

Evaluation of noise-induced hearing loss by reference to the upper limit of hearing

We have defined the upper limit of hearing as the maximum audible frequency measured with fixed intensity and changing frequency. We have previously established the standard upper limit ageing curves from the normal age variation in the upper limit of hearing. In the present study, we sought to clarify the effects of occupational noise on the upper limit of hearing. We measured the upper limit of hearing in 239 healthy male workers (478 ears) exposed to intensive occupational noise. Their age variation in the upper limit of hearing was compared with the standard upper limit ageing curves in males. There were statistically significant deteriorations. Even if the ears that had normal hearing levels (35 dB or less) were selected, deterioration in the upper limit of hearing was noticeable. The upper limit of hearing may serve as clinically useful information on the hearing impairment that precedes noticeable hearing impairment in conventional audiometry for workers exposed to intensive occupational noise.