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Make Some Noise S01 [1080p]


Make Some Noise S01 [1080p]

The Sennheiser HD 560S are sub-par for sports and fitness, though they aren't meant for this purpose. While they offer a surprisingly stable fit, they're still quite bulky and don't have any sort of on-board controls to make playback adjustments. Their audio cable can also snag on something while you're on the go.

The treble accuracy is impressive. Aside from a slight rise in the mid-treble range that makes some notes sound a little piercing, sibilants and cymbals should be perceived as detailed and clearly articulated.

The peaks and dips performance is great. There's a dip in the right driver in the high-mid range that slightly weakens some vocals and lead instruments, but this isn't too noticeable overall. Peaks in the low and mid-treble range make some notes sound a little harsh and piercing too. Other than that, however, the rest of the frequency range is quite flat.

Sound fields are categorized as near field or far field, a distinction that is important to the reliability of measurements. The near field is the space immediately around the noise source, sometimes defined as within the wavelength of the lowest frequency component (e.g., a little more than 4 feet for a 25-Hz tone, about 1 foot for a 1,000-Hz tone, and less than 7 inches for a 2,000-Hz tone). Sound pressure measurements obtained with standard instruments within the near field are not reliable because small changes in position can result in big differences in the readings.

Sensorineural hearing loss tends to be a permanent condition that is often associated with irreversible damage to the inner ear. The normal aging process and excessive noise exposure are both notable causes of sensorineural hearing loss. Studies show that exposure to noise damages the sensory cilia that line the cochlea. Even moderate noise can cause twisting and swelling of the cilia and biochemical changes that reduce cilia sensitivity to mechanical motion, resulting in auditory fatigue. As the severity of the noise exposure increases or if the noise exposure is chronic, the cilia and supporting cells disintegrate and the associated nerve fibers eventually disappear. Occupational noise exposure is a significant cause of sensorineural hearing loss, which appears on sequential audiograms as declining sensitivity to sound, typically first at high frequencies (4,000 Hz), and then lower frequencies as damage continues. Often the audiogram of a person with sensorineural hearing loss will show a "Notch" between 3,000 Hz and 6,000 Hz, and most commonly at 4,000 Hz. This is a dip in the person's hearing level at 4,000 Hz and is an early indicator of sensorineural hearing loss due to noise. Results are the same for audiometric hearing tests and bone conduction testing. Sensorineural hearing loss can also result from other causes, such as viruses (e.g., mumps), congenital defects, and some medications. Modern hearing aids, though expensive, are able to adjust background sounds, changing signal-to-noise ratios, and support hearing and speech discrimination despite the diffuse nature of sensorineural hearing loss. The role of cochlear implants remains unclear.

Tinnitus, or "ringing in the ears," is a common byproduct of overexposure to noise and can occur after long-term exposure to high sound levels, or sometimes from short-term exposure to very high sound levels, such as gunshots. Other physical and physiological conditions are also known to cause tinnitus. Regardless of the cause, this condition is actually a disturbance produced by the inner ear and interpreted by the brain as sound. Individuals with tinnitus describe it as a hum, buzz, roar, ring, or whistle, which can be short term or permanent. Noise-exposed workers may not associate tinnitus with noise exposure or be aware that tinnitus may be an early indicator of overexposure to noise. Hearing conservation training is often focused on noise-induced hearing loss (NIHL) and may not address tinnitus awareness and prevention adequately.

In some individuals, excessive noise exposure can contribute to other physical effects. These can include muscle tension and increased blood pressure (hypertension). Noise exposure can also cause a stress reaction, interfere with sleep, and cause fatigue.

Impulsive/impact noise is typically generated by the rapid release of compressed gases (impulse) or the collision of solid objects (impact) and is defined as the instantaneous change in sound pressure over a short period of time. Examples may include the impact of two metal objects, or the shooting of a firearm. The standard states that exposure to impulsive or impact noise should not exceed a 140-dB peak sound pressure level. Impulsive or impact noises are considered to be much more harmful to hearing than continuous noises. In construction, most of the 500,000 workers who are exposed to hazardous noise levels are also exposed to impulsive and impact noise sources on worksites. Impulsive and impact noise is typified by a sound that rapidly rises to a sharp peak and then quickly fades. Both are transient noises of brief duration and high intensity. The sound may or may not have a "ringing" quality (such as a striking a hammer on a metal plate or a gunshot in a reverberant room). Impulsive noise can be repetitive or a single event (like a sonic boom); if impulses occur in very rapid succession (such as with some jack hammers), it is not described as impulsive or impact noise.

Animal and epidemiological studies have demonstrated that combined exposure to noise and some chemicals (e.g., solvents) induces synergistic adverse effects on hearing. Experimental studies have explored specific substances, including toluene, styrene, ethylbenzene, and trichloroethylene. A 2019 study found that organic solvents benzene, ethylbenzene, and toluene were significantly associated with increased adjusted odds of high-frequency hearing loss ( ).

Much industrial noise can be controlled through simple solutions. It is important, however, that all individuals administering abatement projects have a good understanding of the principles of noise control and proper use of acoustical materials. Industrial hygienists, safety professionals, facility engineers, and others can make significant progress in reducing equipment noise levels and worker noise exposures by combining their knowledge of acoustics with an understanding of the manufacturing equipment and/or processes.

High-velocity fluid flow can often create excessive noise as the transported medium passes through control valves or simply passes through the piping. Frequently, noise is carried downstream by the fluid, and/or vibratory energy is transferred to the pipe wall. A comprehensive acoustical survey can isolate the actual noise source so that the appropriate noise-control measures can be identified. When deemed practical, some effective modifications for high-velocity fluid-flow noise include:

Most industrial equipment vibrates to some extent. Determining whether or not the vibrating forces are severe enough to cause a problem is accomplished through a comprehensive noise and/or vibration survey. As machines operate, they produce either harmonic forces associated with unbalanced rotating components or impulsive forces attributed to impacts such as punch presses, forging hammers, and shearing actions. Excessive noise can be one result of the vibratory energy produced; however, potential damage to the equipment itself, the building, and/or the product being manufactured is more likely. Quite often, vibration problems are clearly identified by predictive-maintenance programs that exist within most industrial plants.

When selecting the appropriate isolation device(s), consider the expertise of trained professionals. It is critical to note that improper selection and installation of isolators can actually make a noise and vibration problem worse. Many manufacturers of vibration isolation equipment have useful websites for troubleshooting problems and finding solutions (see the Noise and Vibration Control Product Manufacturer Guide for a partial list of manufacturers).

For retrofitting pneumatic devices, selecting the appropriate silencer type is critical for this control measure to succeed over time. If the source is a solenoid valve, air cylinder, air motor, or some other device that simply exhausts compressed air to the atmosphere, then a simple diffuser-type silencer will suffice. The disadvantage of these types of devices is that they can cause unacceptable back pressure. Therefore, when selecting a diffuser silencer, it is important that the pressure-loss constraints for the particular application be satisfied. Diffuser silencers can provide 15-30 dB of noise reduction.

The noise reduction provided by a barrier is a direct function of its relative location to the source and receiver, its effective dimensions, and the frequency spectrum of the noise source. The practical limits of barrier attenuation will range from 15 to 20 dB. For additional details on calculating barrier insertion loss or attenuation, the user should review some of the references, particularly The Noise Manual (AIHA, 2003; or latest edition). Recommendations for acoustical barrier design and location to maximize noise reduction capabilities include:

Earplugs come in a variety of sizes, shapes, and materials and can be reusable and/or disposable (Figure 10). Earplugs are designed to occlude the ear canal when worn. All hearing protectors are provided with an NRR. Although earplugs can offer protection against the harmful effects of impulse noise, and some earplugs are designed specifically to reduce this type of noise, the NRR is based on the attenuation of continuous noise and may not be an accurate indicator of the protection attainable against impulse noise. Earplugs are better suited for warm and/or humid environments, such as foundries, smelters, glass works, and outside construction in the summer.

When utilizing HPDs, consideration must also be given for potential interference with communication requirements at the worksite, as they may make it difficult to hear warning alarms such as equipment alarms, emergency notifications, or backup alarms on mobile equipment. In these situations, communication headsets with integrated hearing protection may be a feasible solution, as they would provide hearing protection while allowing workers to hear and communicate with others. In addition, HPD fit-testing could be utilized to determine the appropriate attenuation for a given environment, by identifying an HPD that would provide necessary attenuation to protect the hearing, but not so much that it would interfere with the ability to hear warning alarms. Special consideration may be needed for workers with pre-existing hearing loss, as use of HPDs may further interfere with their ability to hear warning signals. However, it should be noted that such workers still must be protected from exposure according to requirements under the general industry and construction noise standards, as applicable, as there is no exception for employees who have diminished capacity to hear or who have been diagnosed as deaf (see letter of interpretation, August 3, 2004). 59ce067264


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