Medical tourism in emerging markets: The role of trust, networks, and word-of-mouth.

ABTRACT Despite the growing popularity of medical tourism (MT) in emerging markets (EMs), little is known about how healthcare providers operationalize. This article analyzes how healthcare providers meet different challenges to market MT in an EM setting. A qualitative method was used for data collection and conducting case studies on healthcare services in the Philippines. The results show that trust and network building are necessary for mitigating the unfavorable characteristics, instability and lack of legitimacy caused by institutional constraints in EM. Word-of-mouth is found to be important to attract new customers and disseminate information about MT services.

Biomass Assessment of Agricultural Crops Using Multi-temporal Dual-Polarimetric TerraSAR-X Data.

The biomass of three agricultural crops, winter wheat (Triticum aestivum L.), barley (Hordeum vulgare L.), and canola (Brassica napus L.), was studied using multi-temporal dual-polarimetric TerraSAR-X data. The radar backscattering coefficient sigma nought of the two polarization channels HH and VV was extracted from the satellite images. Subsequently, combinations of HH and VV polarizations were calculated (e.g. HH/VV, HH + VV, HH × VV) to establish relationships between SAR data and the fresh and dry biomass of each crop type using multiple stepwise regression. Additionally, the semi-empirical water cloud model (WCM) was used to account for the effect of crop biomass on radar backscatter data. The potential of the Random Forest (RF) machine learning approach was also explored. The split sampling approach (i.e. 70% training and 30% testing) was carried out to validate the stepwise models, WCM and RF. The multiple stepwise regression method using dual-polarimetric data was capable to retrieve the biomass of the three crops, particularly for dry biomass, with R2 > 0.7, without any external input variable, such as information on the (actual) soil moisture. A comparison of the random forest technique with the WCM reveals that the RF technique remarkably outperformed the WCM in biomass estimation, especially for the fresh biomass. For example, the R 2 > 0.68 for the fresh biomass estimation of different crop types using RF whereas WCM show R 2 < 0.35 only. However, for the dry biomass, the results of both approaches resembled each other.

New perspectives on counselling in audiological habilitation/rehabilitation.

OBJECTIVE: To develop and apply a pedagogical method focusing on Empowerment, Empathy, Competence, and Counselling: the EC programme, and to present an initial evaluation. DESIGN: The EC programme was gradually developed within a study circle framework and in dialogue with study circle leaders and participants (clients) with hearing impairment (HI). An evaluation was carried out with the study circle leaders. STUDY SAMPLE: Seventeen upper secondary school students with HI took part in the development of the programme. Eighteen study circle leaders responded to a questionnaire. RESULTS: The EC programme developed consisted of films, CD, and DVD productions to increase insight into one's own hearing ability, to demonstrate for others what HI means, strategies to evaluate situations, and help to act constructively in social situations. The study circle leaders found most of the course material appropriate and easy to use, as a whole or in parts. The leaders' evaluations indicated that the clients had increased their knowledge about how the HI affected themselves and others. The clients had improved their self-confidence and their empathic view of others. CONCLUSION: The EC programme can be used in its entirety or in part. Participation may lead to increased empowerment, empathy, competence and counselling ability.

Hearing impairment and self-masking: listening during vocalization.

OBJECTIVES: To describe the masking effect of a vocalized [a:] on noise bands and speech in persons with mild-to-moderate hearing impairment (HI). DESIGN: The masked threshold of noise bands (250-8000 Hz), continuous discourse, and the amount of masking produced were determined. The maximal vocalization level was determined, that still allowed the subject to just follow the continuous discourse. STUDY SAMPLE: Twenty persons with sensory-neural HI, twelve with a high-frequency (HF) loss and eight with low-, mid-frequency or flat (LMF) loss. RESULTS: The [a:] gave a significantly higher masked threshold at 70 and 80 dBA vocalization for subjects with HF loss than for normal-hearing (NH) subjects, and somewhat higher thresholds than for those with LMF loss. The amount of masking produced was significantly smaller for subjects with HI than NH. CONCLUSIONS: It is important to consider masking effects of self-produced sounds in auditory rehabilitation, and in the future design of hearing aids.

Hearing speech in music.

The masking effect of a piano composition, played at different speeds and in different octaves, on speech-perception thresholds was investigated in 15 normal-hearing and 14 moderately-hearing-impaired subjects. Running speech (just follow conversation, JFC) testing and use of hearing aids increased the everyday validity of the findings. A comparison was made with standard audiometric noises [International Collegium of Rehabilitative Audiology (ICRA) noise and speech spectrum-filtered noise (SPN)]. All masking sounds, music or noise, were presented at the same equivalent sound level (50 dBA). The results showed a significant effect of piano performance speed and octave (P<.01). Low octave and fast tempo had the largest effect; and high octave and slow tempo, the smallest. Music had a lower masking effect than did ICRA noise with two or six speakers at normal vocal effort (P<.01) and SPN (P<.05). Subjects with hearing loss had higher masked thresholds than the normal-hearing subjects (P<.01), but there were smaller differences between masking conditions (P<.01). It is pointed out that music offers an interesting opportunity for studying masking under realistic conditions, where spectral and temporal features can be varied independently. The results have implications for composing music with vocal parts, designing acoustic environments and creating a balance between speech perception and privacy in social settings.

Assessment of auditory brainstem function in lead-exposed children using stapedius muscle reflexes.

The purpose of this study was to investigate the neurological integrity and physiological status of the auditory brainstem tracts and nuclei in children with chronic lead (Pb) exposure using non-invasive acoustic stapedius reflex (ASR) measurements of afferent and efferent-neuromuscular auditory function. Following audiological examinations, uncrossed (ipsilateral) and crossed (contralateral) brainstem ASR responses were evoked by pure tone (500, 1000, and 2000 Hz), and broadband noise (bandwidth: 125-4000 Hz) stimulus activators. The ASR threshold (ASRT), amplitude growth, and decay/fatigue were measured by conventional clinical middle ear immittance methods in a group of Andean children (age range: 2-18 years) with a history of chronic environmental Pb exposure from occupational Pb glazing. Blood lead (PbB) levels of the study group (n=117) ranged from 4.0 to 83.7 µg/dL with a mean PbB level of 33.5 µg/dL (SD: 23.6; median: 33.0: CDC III Classification). The PbB distribution data indicated that 77.8% (n=91) of the children had PbB levels greater than the CDC action line of 10 µg/dL. Repeatable, normal ASRTs were elicited for ipsilateral (mean: ≤90 dB HL) and contralateral (mean: ≤97 dB HL) stimulation for each acoustic activator. Spearman Rho correlation analysis indicated no significant association between PbB level and ipsilateral or contralateral ASRT for any of the stimulus activators. The ASR amplitude growth results showed typical growth functions with no Pb-associated aberrations. No statistical association was found between ASR decay/adaptation (ASRD) and PbB level for any of the stimulus activators. The results of stapedius muscle reflex testing using several stimulus activators showed no significant relationship between PbB level and the physiological integrity of the auditory brainstem mediated ASR responses in children with chronic Pb exposure and elevated PbB levels.

On the problem of listening while talking.

The Gauffin and Sundberg technique of assessing masking during vocalization was modified and tested on 22 normal-hearing and 20 hearing-impaired subjects. The masking effect of the vocalized [a:] on narrow-band noise pulses (250-8,000 Hz) and on test reading was studied. The results showed that the female voice was about 4 dB more efficient in masking external speech compared to the male voice and that the female voice had a high-frequency bias of masking the narrow-band noise, whereas the male voice had a low-frequency bias. Subjects with hearing impairment in the high frequencies were particularly impaired by the masking caused by their own voice. The implications for multilogue conversations and auditory rehabilitation are discussed.

Self-masking: Listening during vocalization. Normal hearing.

What underlying mechanisms are involved in the ability to talk and listen simultaneously and what role does self-masking play under conditions of hearing impairment? The purpose of the present series of studies is to describe a technique for assessment of masked thresholds during vocalization, to describe normative data for males and females, and to focus on hearing impairment. The masking effect of vocalized [a:] on narrow-band noise pulses (250-8000 Hz) was studied using the maximum vocalization method. An amplitude-modulated series of sound pulses, which sounded like a steam engine, was masked until the criterion of halving the perceived pulse rate was reached. For masking of continuous reading, a just-follow-conversation criterion was applied. Intra-session test-retest reproducibility and inter-session variability were calculated. The results showed that female voices were more efficient in masking high frequency noise bursts than male voices and more efficient in masking both a male and a female test reading. The male had to vocalize 4 dBA louder than the female to produce the same masking effect on the test reading. It is concluded that the method is relatively simple to apply and has small intra-session and fair inter-session variability. Interesting gender differences were observed.

Analysis of gene polymorphisms associated with K ion circulation in the inner ear of patients susceptible and resistant to noise-induced hearing loss.

Noise-induced hearing loss (NIHL) is one of the leading occupational health risks in industrialized countries. It results from an interaction between environmental and genetic factors, however the nature of the genetic factors contributing to NIHL has not yet been clarified. Here, we investigated whether genetic variations in 10 genes putatively involved in the potassium recycling pathway in the inner ear may influence susceptibility to noise. 99 SNPs were genotyped in Polish noise-exposed workers, categorized into susceptible and resistant subjects. The most interesting results were obtained for KCNE1 and KCNQ4 as we replicated associations that were previously reported in a Swedish sample set, hence confirming that they are NIHL susceptibility genes. Additionally we report significant associations in GJB1, GJB2, GJB4, KCNJ10 and KCNQ1, however due to the lack of replication in the Swedish sample set, these results should be seen as suggestive.

Variations in HSP70 genes associated with noise-induced hearing loss in two independent populations.

Noise-induced hearing loss (NIHL) is one of the most important occupational health hazards. Millions of people worldwide are exposed daily to harmful levels of noise. NIHL is a complex disease resulting from an interaction between genetic and environmental factors. Although the environmental risk factors have been studied extensively, little is known about the genetic factors. Heat-shock proteins (HSPs) are induced after exposure to severe noise. When first induced by exposure to moderate sound levels, they can protect the ear from damage from excessive noise exposure. This protection is highly variable between individuals. An association of HSP70 genes with NIHL has been described by Yang et al (2006) in a Chinese sample set of noise-exposed workers. In this study, three polymorphisms (rs1043618, rs1061581 and rs2227956) in HSP70-1, HSP70-2 and HSP70-hom, respectively, were genotyped in 206 Swedish and 238 Polish DNA samples of noise-exposed subjects and analyzed. One SNP, rs2227956 in HSP70-hom, resulted in a significant association with NIHL in both sample sets. In addition, rs1043618 and rs1061581 were significant in the Swedish sample set. Analysis of the haplotypes composed of the three SNPs revealed significant associations between NIHL and haplotype GAC in both sample sets and with haplotype CGT in the Swedish sample set. In conclusion, this study replicated the association of HSP70 genes with NIHL in a second and third independent noise-exposed sample set, hereby adding to the evidence that HSP70 genes may be NIHL susceptibility genes.

Perception of the acoustic environment and neuroimaging findings: a report of six cases with a history of closed head injury.

CONCLUSION: The main finding was the relation between difficulty in determining the direction of movement of a sound source and frontal lesions and poor working memory. Poor correspondence in some cases between functional findings and imaging findings can be due to the possibility of axonal degeneration as well as plastic reorganization. OBJECTIVE: The purpose of the present investigation of six cases was to identify auditory, cognitive and neuroimaging long-term sequelae of closed head injury (CHI) with particular focus on environmental sound recognition and moving sound sources. SUBJECTS AND METHODS: Six subjects who had experienced CHI were investigated with auditory tests. Four subjects also completed cognitive testing. CT and MRI were performed. RESULTS: There was a large individual variability of the test results with respect to morphological findings. In five cases with central auditory processing disorders morphological brain damage was demonstrated. Two cases with shortcomings on cognitive testing and with frontal brain lesions demonstrated problems in determining the direction of movement of a sound source. The results may indicate that basal frontal lobe structures play a role in following and determining the direction of movement of a sound source. Two cases had problems with environmental sound recognition; in one left temporal brain lesions were demonstrated.

Vibrotactile identification of signal-processed sounds from environmental events.

This study compared three different signal-processing principles (eight basic algorithms)-transposing, modulating, and filtering-to find the principle(s)/algorithm(s) that resulted in the best tactile identification of environmental sounds. The subjects were 19 volunteers (9 female/10 male) who were between 18 and 50 years old and profoundly hearing impaired. We processed sounds produced by 45 representative environmental events with the different algorithms and presented them to subjects as tactile stimuli using a wide-band stationary vibrator. We compared eight algorithms based on the three principles (one unprocessed, as reference). The subjects identified the stimuli by choosing among 10 alternatives drawn from the 45 events. We found that algorithm and subject were significant factors affecting the results (repeated measures analysis of variance, p < 0.001). We also found large differences between individuals regarding which algorithm was best. The test-retest variability was small (mean +/- 95% confidence interval = 8 +/- 3 percentage units), and no correlation was noted between identification score and individual vibratory thresholds. One transposing algorithm and two modulating algorithms led to significantly better results than did the unprocessed signals (p < 0.05). Thus, the two principles of transposing and modulating were appropriate, whereas filtering was unsuccessful. In future work, the two transposing algorithms and the modulating algorithm will be used in tests with a portable vibrator for people with dual sensory impairment (hearing and vision).

Auditive identification of signal-processed environmental sounds: monitoring the environment.

The goal of the present study was to compare six transposing signal-processing algorithms based on different principles (Fourier-based and modulation based), and to choose the algorithm that best enables identification of environmental sounds, i.e. improves the ability to monitor events in the surroundings. Ten children (12-15 years) and 10 adults (21-33 years) with normal hearing listened to 45 representative environmental (events) sounds processed using the six algorithms, and identified them in three different listening experiments involving an increasing degree of experience. The sounds were selected based on their importance for normal hearing and deaf-blind subjects. Results showed that the algorithm based on transposition of 1/3 octaves (fixed frequencies) with large bandwidth was better (p<0.015) than algorithms based on modulation. There was also a significant effect of experience (p<0.001). Adults were significantly (p<0.05) better than children for two algorithms. No clear gender difference was observed. It is concluded that the algorithm based on transposition with large bandwidth and fixed frequencies is the most promising for development of hearing aids to monitor environmental sounds.

Communication as an ecological system.

A conceptual framework for human communication, based on traditional biological ecology, is further developed. The difference between communication at the message and behavioural levels is emphasized. Empirical data are presented from various studies, showing that degree of satisfaction with communication is correlated with how close the outcome is to the memory of function prior to hearing impairment. We found no indication that hearing-impaired subjects overestimated their previous hearing or the hearing of normal-hearing people. Satisfaction was also correlated with the outcome and degree of fulfillment of expectations. It did not correlate with improvement of function. The concept of balance was presented and tested using a semi-quantitative approach. Several projects were presented in which the framework was applied: the hearing impaired as counsellor, choosing sides in unilateral deafness, a monitoring device for the deafblind, interaction between Swedish as a second language and hearing impairment, language development in hearing impaired children. By regarding hearing as a component of a communicative system, the perspective of audiological analysis and rehabilitation is broadened.

Effect on directional hearing in hunters using amplifying (level dependent) hearing protectors.

BACKGROUND: Ear protectors have gained limited use in real hunting situations because they interfere with rifle handling, eye glasses, listening to conversation and environmental sounds, and impair sound localization ability. Level-dependent protectors have relieved some drawbacks, but sound localization is still affected by most protectors. A new, all-in-the-ear protector is promising, and the primary purpose of this study was to investigate influence of all-in-the-ear protectors on sound localization. STUDY DESIGN: Experimental laboratory study. SETTING: Clinical research center. Tertiary referral center. MATERIALS AND METHODS: Eleven normal-hearing hunters participated. Realistic sounds were presented from an array of 12 loudspeakers in an anechoic chamber, the sounds being gunshot, breaking twig, human footstep, and dog barking. Four listening conditions were tested: without hearing protection, level-dependent dichotic ear muffs, behind-the-ear protectors, and all-in-the-ear protectors. RESULTS: The unprotected condition gave best sound localization results. All-in-the-ear protectors showed slightly and nonsignificantly poorer results, whereas regular ear muffs and behind-the-ear protectors were significantly poorer in this respect. Gun shot, human footstep, twig breaking, and dog barking showed different results in falling order as regards the possibility to localize the sound source. CONCLUSION: All-in-the-ear protectors preserve the sound localization ability well in contrast to the other tested protectors, which present confusions particularly around the transversal plane. The sound localization ability is markedly different for the 4 tested realistic sounds.

Susceptibility to impulse noise trauma in different species: guinea pig, rat and mouse.

CONCLUSION: The results indicate that susceptibility to impulse noise differs in the three species. OBJECTIVE: To test the hypothesis that there is different susceptibility to impulse noise trauma in three species: the guinea pig, rat and mouse. MATERIALS AND METHODS: Three groups of animals were exposed to the same impulse noise and the effect on cochlear pathology was examined using auditory brainstem response thresholds. RESULTS: It was found that the rat and mouse are more sensitive to impulse noise than the guinea pig.

Association between variations in CAT and noise-induced hearing loss in two independent noise-exposed populations.

Noise-induced hearing loss (NIHL) is an important occupational hazard that results from an interaction between genetic and environmental factors. Although the environmental risk factors have been studied quite extensively, little is known about the genetic factors. On the basis of multiple studies, it was proposed that oxidative stress plays an important role in the development of NIHL. Here, we investigated whether variations (single nucleotide polymorphisms; SNPs) in the catalase gene (CAT), one of the genes involved in oxidative stress, influence noise susceptibility. Audiometric data from 1261 Swedish and 4500 Polish noise-exposed labourers were analysed. DNA samples were collected from the 10% most susceptible and the 10% most resistant individuals. Twelve SNPs were selected and genotyped. Subsequently, the interaction between noise exposure and genotypes and their effect on NIHL were analysed using logistic regression. Significant interactions were observed between noise exposure levels and genotypes of two SNPs for the Swedish population and of five SNPs for the Polish population. Two of these SNPs were significant in both populations. The interaction between predictor haplotypes and tagSNP haplotypes and noise exposure levels and their effect on NIHL were also analysed, resulting in several significant associations. In conclusion, this study identified significant associations between catalase SNPs and haplotypes and susceptibility to development of NIHL. These results indicate that catalase is a NIHL susceptibility gene, but that the effect of CAT polymorphisms can only be detected when noise exposure levels are taken into account.

Speech and language development in a population of Swedish hearing-impaired pre-school children, a cross-sectional study.

OBJECTIVE: There is little information on speech and language development in pre-school children with mild, moderate or severe hearing impairment. The primary aim of the study is to establish a reference material for clinical use covering various aspects of speech and language functions and to relate test values to pure tone audiograms and parents' judgement of their children's hearing and language abilities. METHODS: Nine speech and language tests were applied or modified, both classical tests and newly developed tests. Ninety-seven children with normal hearing and 156 with hearing impairment were tested. Hearing was 80 dB HL PTA or better in the best ear. Swedish was their strongest language. None had any additional diagnosed major handicaps. The children were 4-6 years of age. The material was divided into 10 categories of hearing impairment, 5 conductive and 5 sensorineural: unilateral; bilateral 0-20; 21-40; 41-60; 61-80 dB HL PTA. The tests, selected on the basis of a three component language model, are phoneme discrimination; rhyme matching; Peabody Picture Vocabulary Test (PPVT-III, word perception); Test for Reception of Grammar (TROG, grammar perception); prosodic phrase focus; rhyme construction; Word Finding Vocabulary Test (word production); Action Picture Test (grammar production); oral motor test. RESULTS: Only categories with sensorineural loss showed significant differences from normal. Word production showed the most marked delay for 21-40 dB HL: 5 and 6 years p<0.01; for 41-60 dB: 4 years p<0.01 and 6 years p<0.01 and 61-80 dB: 5 years p<0.05. Phoneme discrimination 21-40 dB HL: 6 years p<0.05; 41-60 dB: 4 years p<0.01; 61-80 dB: 4 years p<0.001, 5 years p<0.001. Rhyme matching: no significant difference as compared to normal data. Word perception: sensorineural 41-60 dB HL: 6 years p<0.05; 61-80 dB: 4 years p<0.05; 5 years p<0.01. Grammar perception: sensorineural 41-60 dB HL: 6 years p<0.05; 61-80 dB: 5 years p<0.05. Prosodic phrase focus: 41-60 dB HL: 5 years p<0.01. Rhyme construction: 41-60 dB HL: 4 years p<0.05. Grammar production: 61-80 dB HL: 5 years p<0.01. Oral motor function: no differences. The Word production test showed a 1.5-2 years delay for sensorineural impairment 41-80 dB HL through 4-6 years of age. There were no differences between hearing-impaired boys and girls. Extended data for the screening test [E. Borg, A. Risberg, B. McAllister, B.M. Undemar, G. Edquist, A.C. Reinholdsson, et al., Language development in hearing-impaired children. Establishment of a reference material for a "Language test for hearing-impaired children", Int. J. Pediatr. Otorhinolaryngol. 65 (2002) 15-26] are presented. CONCLUSIONS: Reference values for expected speech and language development are presented that cover nearly 60% of the studied population. The effect of the peripheral hearing impairment is compensated for in many children with hearing impairment up to 60 dB HL. Above that degree of impairment, language delay is more pronounced, probably due to a loss of acuity. The importance of central cognitive functions, speech reading and signing for compensation of peripheral limitations is pointed out.

Ventral approach to rat inner ear preserves cochlear function.

CONCLUSION: This technique enabled us to visualize the cochlea without causing damage. OBJECTIVE: The mammalian inner ear is difficult to approach surgically. This is particularly true in the cases of the rat and mouse, which both have small cochleae. Rat and mouse research is particularly important because their genomes are well characterized, and significantly similar to that of the human. The aim of the present study was to develop a method of accessing the rat cochlea without affecting its function. MATERIALS AND METHODS: In the ventral approach, a small hole was made for access to the scala tympani. Cochlear function was assessed through auditory brainstem response (ABR) threshold measurements. RESULTS: The ventral approach enabled the direct visualization of the tympanic bulla. Thus, the tympanic bulla could be easily opened in a manner that was benign to cochlear function. There was no significant difference in ABR threshold before and after surgery.

Low-dose, long-term caroverine administration attenuates impulse noise-induced hearing loss in the rat.

CONCLUSION: Physiological and morphological assessments indicated that low-dose and long-term caroverine delivery might be a new approach to protect against impulse noise-induced hearing loss. BACKGROUND: Although the exact mechanisms by which impulse noise causes hearing loss are still unclear, there is accumulating evidence that increased reactive oxygen species (ROS) production and excessive glutamate released from the inner hair cells lead to hair cell loss and consequently hearing loss. Caroverine is an antagonist of two glutamate receptors, alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) and N-methyl-D-aspartate (NMDA) receptors in the inner ear, as well as an antioxidant. MATERIALS AND METHODS: In this study, caroverine was delivered subcutaneously using an osmotic pump. This kind of delivery has the advantage, via continuous, long-term and low dose drug administration, of avoiding systemic side effects. RESULTS: It was shown that caroverine could significantly protect the cochlea against impulse noise trauma.