Scandinavian audiology. Supplementum最新文献

Noise induced hearing loss is accompanied by a wide variety of hearing deficits, including threshold and suprathreshold deficits, which often prevent effective rehabilitation even when hearing aids are used. A study of the neural mechanisms responsible for deficits associated with sensorineural loss is based on neurophysiological and anatomical research. In this paper, we intend to review the basic physiological characteristics of the peripheral auditory system.

Temporary threshold shift (TTS) as well as permanent threshold shift (PTS) represent the most common hearing effect of acute and chronic high level acoustic stimulation. TTS is typically related to the traumatizing stimulus spectrum and to the exposure level and duration. The stapedial acoustic reflex as well as the repetition rate of the exposure may influence TTS. PTS is related to a number of factors including exposure duration, subject's age, exposure to other ototoxic factors, presence of impulse noise components, etc. PTS is usually accompanied with alterations of several cochlear functions leading to altered speech discrimination mostly in presence of background noise. The main characteristics of both TTS and PTS are reviewed and discussed.

In military life, noise has unusual characteristics and constitutes a serious hazard for hearing. Hearing impairments due to the exposure to weapon noises represent an important prejudice for the health of many soldiers. A special attention is given to (i) the "critical level", (ii) the frequency localization of the threshold shifts, (iii) the actual influence of the protective reflexes of the ear, (iv) the existence of delayed threshold shifts following impulse noise exposures, and (v) the interest of the medical treatment of the acoustic trauma. Damage risk criteria for weapon noises are compared: criteria using the (A-weighted) isoenergy principle represent the best present solution (LAeq = 85 dB). Specific problems related to the use of hearing protection are also discussed.

Noise-induced hearing loss (NIHL) has no specific of exclusive audiological signs. The disorder is identified on the strength of a high probability conclusion and as a result of an exclusion process. Because of frequent legal purposes, audiometrical data measured and analyzed have furthermore to be as accurate and reliable as possible. The paper outlines the whole procedure involved in the audiological assessment of noise-induced hearing loss considering different stages for: suspicion and identification, hearing threshold measurement, etiological and differential diagnosis, apportionment.

Recent investigations have demonstrated that in animal models repeated exposures to mid-intensity noise induce a progressive reduction of the temporary threshold shift (TTS) following the exposures. This phenomenon is named "conditioning" and it is actually able to reduce the permanent threshold shift (PTS) following exposure to high intensity noise; this finding is named "toughening". In the present work the fundamental steps of the research concerning the toughening are reviewed and the biological mechanisms supposed to be underlying this phenomenon discussed. The few preliminary results of the studies on humans are also reported.

A medical-legal and scientific topic of longstanding interest is the interaction between presbyacusis and noise-induced permanent threshold shift (NIPTS). Current medical-legal practices as well as international standard, ISO 1999 International Organization for Standards: Acoustics: Determination of Occupational Noise Exposure and Estimation of Noise-Induced Hearing Impairment. ISO 1999. Geneva, International for Standards, 1990 assume that NIPTS and hearing loss caused by the aging process add in dB. Results of laboratory studies with animals are inconsistent in their support of the "additivity assumption". When intense, short-duration exposures are used, the predictions of the combined effects of noise and age are too large. The additivity model appears to be supported with long-duration exposures, but we question the accuracy of such predictions. The animal studies reviewed here suggest that the allocation of hearing loss in an older individual into a noise component and an aging component is much more complex than "additivity in dB".

This paper is an overview of the research we have carried out at Linköping University on cognitive aspects of visual language processing and related communicative forms. In the first section, a cognitive individual difference perspective on speechreading is introduced. In the second, compensatory perceptual mechanisms are discussed on the basis of behavioral and neurophysiological data. The third section addresses further the issue of perceptual versus cognitive compensation, and the fourth and fifth sections apply a set of cognitive tests based on the concept of working memory for poorly specified language input to data on the successes and failures with cochlear implants, tactile aids and hearing aids.

Much of our present understanding of sensory processing by the human brain is obtained from studies of patients with sensory impairments. Past auditory studies have focused strongly on the peripheral mechanisms of hearing disorders, and have led to an overuse of stimuli that are good for testing the transfer functions of simple acoustic features but are not suitable for understanding the perception of complex auditory stimuli or stimulus sequences. Magnetoencephalography (MEG) is a non-invasive method for studying how the human brain processes and stores auditory information. The long-term groundwork in building up the basic understanding of cortical dynamics during various "simple" stimulations now allows the use of more complex, real-life-like stimuli, and clinical applications.

Encounters are one of the basic dynamics of society, although this does not imply that macro-phenomena do not have ontological status. Encounters involve interaction and hence communication, and interaction and communication generate emotions. Emotions are of great significance to our well-being. Disturbed communication is by far the most commonly reported effect of hearing loss and many handicaps resulting from hearing impairment are of an emotional character. Following Goffman and Scheff I argue that fear of losing face is crucial in interaction, and that shame is an important emotion. Shame is often hidden, misnamed or avoided. But if shame is acknowledged, it is discharged. In traditional audiological rehabilitation, the focus is aural perception, visual perception and speech. I contend that emotional problems, like shame and embarrassment, have to be brought to the fore, the focus less on the compensatory side of rehabilitation and more on the acceptance and coping sides.

When central auditory dysfunction is present, ability to understand speech in difficult listening situations can be affected. To study this phenomenon, dichotic speech tests were performed with test material in the Swedish language. Digits, spondees, sentences and consonant-vowel syllables were used as stimuli and the reporting was free or directed. The test material was recorded on CD. The study includes a normal group of 30 people in three different age categories; 11 years, 23-27 years and 67-70 years. It also includes two different groups of subjects with suspected central auditory lesions; 11 children with reading and writing difficulties and 4 adults earlier exposed to organic solvents. The results from the normal group do not show any differences in performance due to age. The children with reading and writing difficulties show a significant deviation for one test with digits and one test with syllables. Three of the four adults exposed to solvents show a significant deviation from the normal group.