Blog Archives
Post exposure treatment with a Src-PTK inhibitor in combination with N-l-acetyl cysteine to reduce noise-induced hearing loss
Both the antioxidant, N-l-acetyl cysteine (NAC), and the Src inhibitor, KX1-004, have been used to protect the cochlea from hazardous noise. In order to extend our previous work on KX1-004 with noise exposure, the current studies were undertaken with two goals: (1) to test the effectiveness of NAC and KX1-004 in combination with one another when given in a protection paradigm, and (2) to test the NAC+KX1-004 combination in a postexposure rescue paradigm. The noise exposure for the first experiment consisted of a 4-kHz octave band of noise at 107 dB SPL for 2 hours. The combination of NAC and KX1-004 were administered either prior to the noise exposure or post exposure (rescue). The second experiment was undertaken to extend the findings of the first experiment’s rescue paradigm. The 4 kHz octave band noise was delivered at 112 dB SPL for 1 hour, with the experimental drugs delivered only in a rescue paradigm. In Experiment 1, animals treated before the 2-hour noise exposure with the combination of NAC and KX1-004 had from 12 to 17 dB less permanent threshold shift when compared to control saline treated animals. Treatment in the rescue paradigm did not produce any reductions in threshold shift from the 2-hour exposure. In the second experiment, with the 1-hour noise, rescue with KX1-004 or KX1-004 plus NAC yielded small, but significant, reductions in threshold shift. There was no additional benefit from the combination of NAC and KX1-004 over KX1-004 by itself.
from Noise & Health
The influence of military service on auditory health and the efficacy of a hearing conservation program
The influence of military service on self-assessed hearing symptoms and measured auditory function was studied as well as the efficacy of the Hearing Conservation Program (HCP) of the Swedish Armed Forces. 839 conscripts were recruited for the study at reporting to military service. They were all exposed to noise over the risk-limits from weapons and vehicles and used earmuffs and/or earplugs. Questionnaires and pure tone screening audiometry were studied at the start and the end of the military service. Retrospective information regarding audiometry at conscription before military service was included as control. The prevalence values of tinnitus were 23% before and 32% after the service and of sensitivity to noise 16% and 19% respectively. The prevalence values of hearing impairment were 6.3% at conscription, 14.5% at reporting to military service, and 24% after the training period. The incidence values of hearing decline were 3.7% during the period with no military noise exposure and 6.6% during the military service. Acoustic accident increased the risk of worsened tinnitus and sensitivity to noise four times and for a high frequency hearing decline six times. We observed elevated prevalence values of tinnitus, sensitivity to noise and hearing impairment at discharge compared to before military service. We observed an elevated risk of hearing decline during military service. Acoustic accident increased the risk of tinnitus, noise sensitivity and hearing decline. We suggest improvements regarding inclusion criteria for military service, and for education regarding the HCP.
from Noise & Health
Sentences recognition thresholds in normal hearing individuals in the presence of inciding noise from different angles
CONCLUSION: The following sentence recognition thresholds in the noise, in sound field, were obtained for these signal-to-noise ratios: 0° – 0° = -7.56 dB; -0º – 90º = -11.11 dB; -0º – 180° = -9.75 dB; 0º – 270º = -10.43 dB. The better thresholds were obtained with the incidence angles of 0º – 90º and 0º – 270º, followed by the 0º – 180º condition, and, finally, by the 0º – 0º condition. The most unfavorable hearing condition was that in which the noise was in the same incidence angle of the speech, in front of the evaluated subject.
Noise exposure in convertible automobiles
Conclusion: Driving convertible automobiles at speeds exceeding 88.5 km/h, with the top open, may result in noise exposure levels exceeding recommended limits, especially when driving with the convertible top open for prolonged periods.
from the Journal of Laryngology and Otology
Effects of Noise and Speech Intelligibility on Listener Comprehension and Processing Time of Korean-Accented English
Conclusion: The findings suggest that decreased speech intelligibility and adverse listening conditions can be major challenges for effective communication between foreign-accented speakers and native listeners. The results also indicate that foreign-accented speech requires more effortful processing relative to native speech under certain conditions, affecting both comprehension and processing efficiency.
Listening Habits of iPod Users
Conclusions: All of the listeners surveyed were exposed to dosages well below OSHA and NIOSH occupational regulations. Although this does not guarantee individual safety, the results do not support the widespread concern regarding the safety of common iPod usage. However, measurements made in this study agree with the finding that iPod output can exceed safe levels and further support recommendations to monitor and limit listening volume and listening duration.
Comparison of fluctuating maskers for speech recognition tests
Objective: To investigate the extent to which temporal gaps, temporal fine structure, and comprehensibility of the masker affect masking strength in speech recognition experiments. Design: Seven different masker types with Dutch speech materials were evaluated. Amongst these maskers were the ICRA-5 fluctuating noise, the international speech test signal (ISTS), and competing talkers in Dutch and Swedish. Study Sample: Normal-hearing and hearing-impaired subjects. Results: The normal-hearing subjects benefited from both temporal gaps and temporal fine structure in the fluctuating maskers. When the competing talker was comprehensible, performance decreased. The ISTS masker appeared to cause a large informational masking component. The stationary maskers yielded the steepest slopes of the psychometric function, followed by the modulated noises, followed by the competing talkers. Although the hearing-impaired group was heterogeneous, their data showed similar tendencies, but sometimes to a lesser extent, depending on individuals’ hearing impairment. Conclusions: If measurement time is of primary concern non-modulated maskers are advised. If it is useful to assess release of masking by the use of temporal gaps, a fluctuating noise is advised. If perception of temporal fine structure is being investigated, a foreign-language competing talker is advised.
from the International Journal of Audiology
Hearing discrimination abilities in children with phonological disorders*
AIM: to investigate the ability of hearing discrimination in children with Phonological Disorders who received or were receiving phonological treatment; to verify if the altered phonemes were the same as those which were not discriminated in the Picture Test for Hearing Discrimination (adapted for Portuguese language by Mota et al 2000, based on “The Boston University Speech Sound Discrimination Picture Test”) and to verify if the ability of hearing discrimination is related to gender, age and the phonological disorder severity level.
Perception of Acoustically Degraded Sentences in Bilingual Listeners Who Differ in Age of English Acquisition
Conclusions: Findings suggest that linguistic background needs to be considered in the understanding of bilingual listeners’ context use in acoustically degraded conditions. Direct comparison of early bilingual listeners’ performance with monolingual norms may be inappropriate when speech is highly degraded.
Audiologic findings and auditory-related complaints of urban bus drivers
CONCLUSION: This study showed a need for the development of preventive actions towards hearing health, in order to promote improvements on work conditions and hearing preservation of bus drivers.
Responses of the ear to low frequency sounds, infrasound and wind turbines
Infrasonic sounds are generated internally in the body (by respiration, heartbeat, coughing, etc) and by external sources, such as air conditioning systems, inside vehicles, some industrial processes and, now becoming increasingly prevalent, wind turbines. It is widely assumed that infrasound presented at an amplitude below what is audible has no influence on the ear. In this review, we consider possible ways that low frequency sounds, at levels that may or may not be heard, could influence the function of the ear. The inner ear has elaborate mechanisms to attenuate low frequency sound components before they are transmitted to the brain. The auditory portion of the ear, the cochlea, has two types of sensory cells, inner hair cells (IHC) and outer hair cells (OHC), of which the IHC are coupled to the afferent fibers that transmit “hearing” to the brain. The sensory stereocilia (“hairs”) on the IHC are “fluid coupled” to mechanical stimuli, so their responses depend on stimulus velocity and their sensitivity decreases as sound frequency is lowered. In contrast, the OHC are directly coupled to mechanical stimuli, so their input remains greater than for IHC at low frequencies. At very low frequencies the OHC are stimulated by sounds at levels below those that are heard. Although the hair cells in other sensory structures such as the saccule may be tuned to infrasonic frequencies, auditory stimulus coupling to these structures is inefficient so that they are unlikely to be influenced by airborne infrasound. Structures that are involved in endolymph volume regulation are also known to be influenced by infrasound, but their sensitivity is also thought to be low. There are, however, abnormal states in which the ear becomes hypersensitive to infrasound. In most cases, the inner ear’s responses to infrasound can be considered normal, but they could be associated with unfamiliar sensations or subtle changes in physiology. This raises the possibility that exposure to the infrasound component of wind turbine noise could influence the physiology of the ear.
from Hearing Research
Reception Thresholds for Sentences in Quiet and Noise for Monolingual English and Bilingual Mandarin-English Listeners
BL listeners display significantly poorer performance when perceiving nonnative L2 sentences in quiet and in continuous and interrupted noise relative ML listeners. When listening to their respective native L1 sentences, only a difference in continuous noise was found. This difference was attributed to differential masking effect on the English stimuli. Similar performance in the interrupted noise between the ML and BL participants with L1 stimuli and the equivalent release from masking with the BL participants for both L1 and L2 stimuli suggest comparable basic auditory temporal resolving capacities between these ethnic groups.
from IngentaConnect
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