Noise-induced temporary threshold shifts: the effects of anticipatory stress and coping strategies

Effects of ear canal occlusion on hearing sensitivity: A loudness experiment

Over the last century, hearing research has repeatedly reported differences in loudness perception when different types of transducers are being used. One of the effects of using different transducers is that listening may be performed via an open ear (loudspeaker), a cushioned ear (headphones), or an occluded ear (hearing aid receivers, insert earphones). The question of whether varying the acoustic load applied to the ear canal might impact hearing sensitivity has therefore become essential given the need to establish realistic noise damage risk criteria in an attempt to prevent noise-induced hearing loss for any given listening condition. Although such loudness discrepancies in the cushioned ear have been recently proven to be caused by loudness measurement artifacts, currently available data do not exclude a possible impact of ear canal occlusion on loudness perception. This paper presents the results of a loudness balance test carried out on 18 normal-hearing listeners. Using an earplug to occlude the canal, in-ear sound pressure levels were compared between the occluded ear and the cushioned ear at equal loudness. The results show agreement within 1 dB between the two listening conditions, and support the conclusion that loudness does not depend on the type of acoustic load applied to the ear canal.

Do venepuncture procedures induce cortisol responses? A review, study, and synthesis for stress research

Venepuncture procedures are frequently employed to continuously monitor humoral stress markers. As such procedures are conceived as "potent psychological and physiological stressors", there is a need to determine whether venepuncture procedures themselves elicit cortisol responses and if so, how to deal with them appropriately. In order to assess the rate of cortisol responses to venepuncture, we conducted a literature review, which suggested that venepuncture procedures induce cortisol responses with a probability of approximately 30%. By utilizing Bayesian analysis, this result was integrated with the cortisol data of 18 healthy men who were exposed to a venepuncture procedure twice (time lag: 1 week). The currently observed response rate of 47% differed substantially from the earlier findings, which we attribute to a self-selective sampling of participants. In addition, participants showing a response to the first venepuncture were highly likely to also show a response to the second one. In this regard, we discuss the presumed conditioning of cortisol responses to venepuncture procedures. To prevent the superposition of venepuncture-induced cortisol responses and responses induced by target stressors, we propose a time- and selection-based strategy: cortisol samples taken about 110min after venepuncture should be virtually adjusted for its superimposing effects. Furthermore, previous experiences of venepuncture were highly predictive for cortisol responsiveness. This association could be utilized in further studies to identify participants who will probably show a cortisol response to venepuncture.

The impact of abbreviated progressive muscle relaxation on salivary cortisol

The purpose of this study was to examine whether acute relaxation training, conducted on two separate occasions, would be associated with reliable reductions in subjective and physiological indices of stress. Forty-six experimental subjects were led through Abbreviated Progressive Relaxation Training (APRT) exercises during two laboratory sessions spaced exactly 1 week apart. Fifteen control subjects experienced two laboratory sessions where they sat quietly for an equal amount of time. Results indicated that a brief relaxation exercise led to experimental subjects having significantly lower levels of post-intervention heart rate, state anxiety, perceived stress, and salivary cortisol than control subjects, as well as increased levels of self-report levels of relaxation. The results of this study may have implications for the use of relaxation training in enhancing immune function.

Pregnancy decision making: predictors of early stress and adjustment

Pregnancy decision making was examined among pregnant and nonpregnant women seeking pregnancy testing. The majority of women had decided upon and were certain of a decision to either abort or carry a possible pregnancy before learning the pregnancy-test results. Adjustment to pregnancy decision making was examined longitudinally among the women who tested positive for pregnancy. Pregnant participants were interviewed about their decisions to carry or abort their pregnancies at three times—immediately prior to pregnancy testing, a day after receiving positive test results, and 4 weeks later. Nearly all maintained their original decision over the course of the study. Adjustment was related primarily to which outcome was chosen and, to a lesser degree, to whether a woman was initially decided or not upon the outcome. The time surrounding pregnancy testing was stressful for women who decided to abort their pregnancies. However, negative feelings at the time of pregnancy testing among those who later aborted their pregnancies subsided by the end of the study and did not differ from those who carried their pregnancies.

Angiotensin II and progesterone effects on laser Doppler measures of cochlear blood flow

Anesthetized, ovariectomized rats were given bolus injections of angiotensin II (AII) or saline vehicle while Cochlear Blood Flow (CBF) changes were measured using a laser Doppler flowmeter. Experimental animals were pretreated with replacement progesterone and control animals were given oil vehicle injections in place of progesterone. AII increased blood pressure and CBF. Progesterone pretreatment augmented AII-induced pressor responses, while slightly depressing the cochlear blood flow response. These results suggest that AII may be involved in the local, autoregulatory control of CBF, and in possible steroid-related alterations of susceptibility to ototraumas.