Monthly Archives: February 2017

Help Your Hearing, Improve Your Social Life, Get Healthier – QUALITY OF LIFE

February 24, 2017

Good hearing keeps you in the game, but how much is good social activity worth?

Various studies have linked social connections to better health and longer life, but it hasn’t been clear whether healthy people were more socially active to begin with.  A  review of 148 studies from researchers at Brigham Young University looked at healthy people who were followed for 7.5 years, on average.  The study(ies) controlled for the health of the subjects.

The results showed that the value of social interaction was stronger and than you might thing.  Based on the data from these studies,  weak social ties in your community are a major risk factor to your health,  at least as harmful to your health as smoking, lack of exercise or obesity. For instance:

  1.  You have a 50% lower risk of dying if you have close friends, family or work relationships.
  2.  Poor socialization threatens your health as much as if you were an alcoholic or were smoking a pack a day.
  3.  Poor social connections are harder on your health than not exercising, or being obese.

The study concludes that medical checkups should screen patients for social well being, with the goal of enhancing social connections.

It goes almost without saying that medical checkups should also screen patients for hearing loss, to ensure that patients have a good shot at maintaining social well being.  We think and hope readers will  agree that hearing well is an essential ingredient for developing and maintaining successful social networks.

Quality of Life

 

 

 

 

 

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What is Noise Induced Hearing Loss?

February 17, 2017

What is Noise Induced Hearing Loss?

Noise induced hearing loss is a permanent hearing impairment resulting from prolonged exposure to high levels of noise. One in 10 Americans has a hearing loss that affects his or her ability to understand normal speech. Excessive noise exposure is the most common cause of hearing loss.

“The National Institute of Health reports that about 15 percent of Americans aged

20 to 69 have high frequency hearing loss related to occupational or leisure activities.”

Because of occupational risk of noise induced hearing loss, there are government standards regulating allowable noise exposure. People working before the mid 1960s may have been exposed to higher levels of noise where there were no laws mandating use of devices to protect hearing. Recent studies show an alarming increase in hearing loss in youngsters. Evidence suggests that loud rock music along with increased use of portable radios with earphones may be responsible for this phenomenon.

When noise is too loud, it begins to kill cells in the inner ear.

As the exposure time to loud noise increases, more and more hair cells are destroyed. As the number of hair cells decreases, so does your hearing. Currently, there is no way to restore life to dead hair cells; the damage is permanent.

The damage caused by noise, called sensorineural hearing loss, can be caused by several factors other than noise, but noise-induced hearing loss is different in one important way – it can be reduced or prevented altogether.

Noise can also cause a reversible hearing loss, called a temporary threshold shift. This typically occurs in individuals who are exposed to gunfire or firecrackers, and hear ringing in their ears after the event (tinnitus).

What Causes Noise Induced Hearing Loss?

First, we have to define noise. Sound can be measured scientifically in two ways — intensity and pitch. Both of these affect the degree to which sound (noise) damages hearing.

NIHL: Intensity of Sound

Intensity of sound is measured in decibels (dB). The scale runs from the faintest sound the human ear can detect, which is labeled 0 dB, to over 180 dB, the noise at a rocket pad during launch. Decibels are measured logarithmically, being 20 times the log of the ratio of a particular sound pressure to a reference sound pressure. This means that as decibel intensity increases by units of 20, each increase is 10 times the lower figure. Thus, 20 decibels is 10 times the intensity of 0 decibels, and 40 decibels is 100 times as intense as 20 decibels. Sound intensity may be given in two different units. Persons interested in the actual physical quantification of sound use units of sound pressure level (SPL). SPL is calibrated to a constant sound pressure level that does not vary with frequency. On audiograms, however, sound intensity is calibrated in hearing level (HL), meaning that the reference sound is one that that just barely heard by a normal population. Thus HL units are relative ones and do not generally correspond to SPL units. Higher intensity (db) of sound causes more damage. Many experts agree that continual exposure to more than 85 decibels may become dangerous.

The following table illustrates some common sounds and their intensity.

Approximate Decibel Level Examples
0 dB the quietest sound you can hear.
30 dB whisper, quiet library.
60 dB normal conversation, sewing machine, typewriter.
90 dB lawnmower, shop tools, truck traffic; 8 hours per day is the maximum exposure (protects 90% of people).
100 dB chainsaw, pneumatic drill, snowmobile; 2 hours per day is the maximum exposure without protection.
115 dB sandblasting, loud rock concert, auto horn; 15 minutes per day is the maximum exposure without protection.
140 dB gun muzzle blast, jet engine; noise causes pain and even brief exposure injures unprotected ears; maximum allowed noise with hearing protector.

NIHL

NIHL: Frequency

Pitch is measured in frequency of sound vibrations per second, called Hertz (Hz). Frequency is measured in cycles per second, or Hertz (Hz). The higher the pitch of the sound, the higher the frequency. A low pitch such as a deep voice or a tuba makes fewer vibrations per second than a high voice or violin. Generally noise induce hearing loss occurs at a pitch of about 2000-4000 Hz. Frequency is measured in cycles per second, or Hertz (Hz). The higher the pitch of the sound, the higher the frequency. Young children, who generally have the best hearing, can often distinguish sounds from about 20 Hz, such as the lowest note on a large pipe organ, to 20,000 Hz, such as the high shrill of a dog whistle that many people are unable to hear.

Human speech, which ranges from 300 to 4,000 Hz, sounds louder to most people than noises at very high or very low frequencies. When hearing impairment begins, the high frequencies are often lost first, which is why people with hearing loss often have difficulty hearing the high-pitched voices of women and children.

Loss of high frequency hearing also can distort sound, so that speech is difficult to understand even though it can be heard. Hearing impaired people often have difficulty detecting differences between certain words that sound alike, especially words that contain S, F, SH, CH, H, or soft C, sounds, because the sound of these consonant is in a much higher frequency range than vowels and other consonants.

 

NIHL:Duration

In addition, the duration (how long you are exposed to a noise) can affect the extent of noise induced hearing loss. The longer you are exposed to a loud noise, the more damaging it may be.

Every gunshot produces a noise that could damage the ears of anyone in close hearing range. Large bore guns and artillery are the worst because they are the loudest. But even cap guns and firecrackers can damage your hearing if the explosion is close to your ear. Anyone who uses firearms without some form of ear protection risks hearing loss.

Excessive noise is present in many situations. Some of the more common ones include occupational noise (machinery, etc.), loud music, and non-occupational noise (lawn mowers, snow blowers, etc.).

NIHL: Occupational Noise

Habitual exposure to noise above 85 dB will cause a gradual hearing loss in a significant number of individuals, and louder noises will accelerate this damage. For unprotected ears, the allowed exposure time decreases by one half for each 5 dB increase in the average noise level. For instance, exposure is limited to 8 hours per day at 90 dB, 4 hours per day at 95 dB, and 2 hours per day at 100 dB. The highest permissible noise exposure for the unprotected ear is 115 dB for 15 minutes per day. Any noise above 140 dB is not permitted.


SOURCE: http://american-hearing.org/disorders/noise-induced-hearing-loss/#whatis

 

How much do you love your hearing and why you should.

February 14, 2017

How much do you love your hearing and why you should.

Of all the five senses it seem that hearing is the most ignored and the most taken for granted. Our generation (Boomers, X&Y) have not done a very good job at preventing hearing loss until its too late.

Whether your 17 or 55 years old, we have all done some sort of damage to our hearing…. 

Some of us have worked in loud noisy places and haven’t really considered protecting our ears except with the odd foam earplug, which are only good for one shift. Or we have worked in an environment where the noise was gradual but still loud and did nothing to protect our hearing since it wasn’t top of mind.

Or how about everyday uses to protect your hearing from noise pollution. Over the past 10 years we all have been embracing iTunes, iPods, Podcasts, SmartPhones, Audiobooks etc. But have we really considered the extra strain all of these technological advances have impacted our ears? Well if you LOVE YOUR HEARING, then I suggest you start.  Remember we live with our hearing and we should love our hearing as it one of the 5 senses that allows to hear the wonderful things in life; things to consider next time you crank up that new hit song, or put in disposable instead of personal hearing protection.

Love your hearing

From all of us at ProtectEar USA – HAPPY VALENTINES DAY!


Basic Facts About Hearing Loss

  • About 20 percent of Americans, 48 million, report some degree of hearing loss.
  • At age 65, one out of three people has a hearing loss.
  • 60 percent of the people with hearing loss are either in the work force or in educational settings.
  • While people in the workplace with the mildest hearing losses show little or no drop in income compared to their normal hearing peers, as the hearing loss increases, so does the reduction in compensation.
  • About 2-3 of every 1,000 children in the United States are born with a detectable hearing loss in one or both ears.
  • Almost 15% of school-age children (ages 6-19) have some degree of hearing loss.

SOURCE: http://www.hearingloss.org/content/basic-facts-about-hearing-loss

The Quantification and Reporting of Hearing Protection Attenuation

February 8, 2017

ProtectEar has produced a series of three articles regarding the challenges to knowing how much protection is given to an associate in a hearing loss prevention program. This the 2nd article in the series, deals with the quantification and reporting of attenuation. The initial article dealt with the history of trying to measure and report attenuation. The final article deals with “After Hearing Loss Prevention, then what?” What are the next steps a firm can apply to go beyond the current practice in hearing loss prevention?

The Quantification and Reporting of Hearing Protection Attenuation

What is the NRR?

The U.S. Environmental Protection Agency (EPA) was charged by the Noise Control Act of 1972 with developing and enforcing regulations pertaining to Product Noise Labeling. As a result the EPA developed 40 CFR 211 Subpart B – Hearing Protective Devices, in which the Noise Reduction Rating (NRR) was defined. The NRR is a single-number rating which has been required by law to be shown on the label of each hearing protective device (HPD) sold in the United States since 1979.

NRR

Before any HPD may be sold in the United States, the manufacturer or distributor must have it tested according to the requirements of the law, submit the data to the EPA, and provide the NRR along with corollary information on the HPD’s packaging. The NRR was intended to allow the consumer to select an HPD appropriate for the noises in which it would be used to prevent noise-induced hearing loss (NIHL). The law requires that the values of sound attenuation used for calculation of the NRR be determined in accordance with ANSI S3.19-1974. It matters not whether the HPD is intended for protection from occupational or recreational noise, or even to reduce the impact of traffic noise or the snoring of a partner on sleep, it must be labeled with the NRR label and corollary information.

Real-ear attenuation at threshold (REAT) is determined by carefully measuring the hearing thresholds of ten (10) normal-hearing members of a subject panel. Their hearing thresholds are measured for narrow bands of noise in a highly specified acoustic environment. Each subject is tested twice; ears open and ears occluded with the HPD being tested. The experimenter-fit method defined in ANSI S3.19 is used. Rather than allowing the subject to put on or remove the HPD, the experimenter fits the hearing protector to the ear of each test subject for each occluded test for what they consider is a best fit. REAT is the difference between the thresholds with the ears occluded and the ears open. Each subject repeats the paired open/occluded test three (3) times. Mean attenuations and standard deviations are calculated in accordance with the standard.

NoiseHealth_

The NRR calculation is specified by the EPA’s law, not the ANSI S3.19 standard. The NRR is computed from the mean attenuations and standard deviations of the attenuations for each of the nine (9) narrow bands of noise. The NRR is intended to predict the minimum amount of protection provided to 98% of potential users.

How has the NRR been used?

The Hearing Conservation Amendment to the Occupational Noise Standard (OSHA, 1983) describes six methods for using the NRR to determine a worker’s protected A-weighted noise exposure. These methods vary according to the instrumentation and parameters used to determine the unprotected noise levels. However, they can be summarized into two basic formulas, depending on whether unprotected exposure levels were measured on a C-weighted or an A-weighted scale. For C-weighted measurements:

Protected dBA = unprotected dBC – NRR

where the protected dBA and the unprotected dBC are 8-hour time-weighted average1s (TWA1s) determined according to the Occupational Noise Standard.

This method is how the NRR was designed to be used. For example, if a protector has an NRR of 17 dB and it is used for an TWA[i] of 95 dBC, the noise level entering the ear could be expected to be 78 dBA [95 – 17 = 78] or lower in 98% of the cases if the protector is worn according to manufacturer’s specification as fitted by the experimenter during the testing.

For A-weighted measurements:

protected dBA = unprotected dBA – [ NRR – 7]

Where, again, the protected and unprotected dBA are 8-hour time-weighted averages determined according to the Occupational Noise Standard (1093).

This method is an adaptation for those whose instrumentation does not have C-weighting capabilities. The 7-dB correction factor is used to account for the de-emphasis of low-frequency energy inherent to the A-weighting scale.

So, for example, if a protector has an NRR of 17 dB and it is used for an environmental noise exposure level of 95 dBA, the noise level entering the ear could be expected to be 85 dBA [95 – (17 – 7) = 85] or less in 98% of the cases.

Problems with the NRR

A study by Berger, Franks, and LIndgren, (1996) evaluated data from 22 studies of real-world REATs. They found that labeled NRRs for the HPDs studied over-estimated the reported REATs by as little as 5% and by as much as 2000%.

NIOSH reevaluated the data and consequently recommended derating the NRR by a multiplicative factor of 75% for earmuffs, 50% for slow-recovery formable earplugs, and 30% for all other earplugs (NIOSH, 1998). The NIOSH derating scheme did not affect the 7-decibel dBC-to-dBA correction as it was applied to the NRR only. Derating was not applied to custom-molded earplugs, however, so they may range from extremely effective (meeting labeled NRR) to completely ineffective (providing no protection at all). It all depends upon the quality of the impression and the quality assurance of the laboratory making the earplug.

OSHA’s approach to using the NRR, while recognizing the NIOSH derating scheme, is to derate the NRR by 50% regardless of hearing protector type when considering whether an HPD will provide adequate hearing protection for a given noise exposure level expressed as a TWA.

Thus, if the noise exposure level were made in dBA, most often the case, the protected exposure level for a 95-dBA exposure and an HPD with an NRR of 29 dB would be 84 dBA – [95 – ((29-7)/2)], 1 dB less than the OSHA Action Level (OSHA, 2016).

So, what do I do with the NRR?

The best approach is to recognize the NRR for what it is: a number derived from a laboratory test that for most pre-molded earplugs and formable (foam) earplugs represents a fitting that you and your employees will not achieve. OSHA’s approach as defined by CPL 02-02-03 dated December 16, 1983 is as follows:

  • Use the NRR as the laboratory-based noise reduction for a given hearing protector.
  • Apply a safety factor of 50 percent; i.e., divide the calculated laboratory-based attenuation by 2.
    • NOTE: This is a general method for taking into consideration OSHA experience and the published scientific literature, which indicate that laboratory-obtained attenuation data for hearing protectors are seldom achieved in the workplace.
    • If a different or no safety factor seems appropriate in a particular instance, it may be used instead. For example, for laboratory-made custom-molded earplugs, NIOSH recommended that no safety factor (derating) be applied.
  • The adjusted noise reduction should be sufficient to meet requirement that the protected noise exposure level be less than the OSHA Action Level of TWA < 85 dBA.

So, if you are using custom molded earplugs, you can take the NRR on the label at face value and apply it as suggested above without applying a safety factor or derating it. For the custom molded earplug, it seems to not matter whether the experimenter or the subject fits it for testing. The outcome is about the same[ii]. 

What is the NRR(SF)?

A New Rating: A new “subject fit” or naïve subject method of measuring HPD attenuation can be used to calculate a different rating; the NRR(SF). The people (subjects) in this laboratory test fit their own protector according to the manufacturer’s instructions without the help of the person conducting the test. While the subjects are very well trained in taking hearing tests, they do not use HPDs regularly, have not participated in an experimenter-fit procedure, and have only used a few HPDs without formal training (hence naïve subject). Compared to the NRR shown on the current EPA label, the NRR(SF) is usually a lower rating that may be closer to the performance of the hearing protector in the real world.

The NRR (SF) was developed by the National Hearing Conservation Association’s (NHCA) Task Force on Hearing Protector Effectiveness to address labeling related issues (Royster, 1995).

How do I use the NRR (SF)?

The NRR(SF) is intended to be used directly with A-weighted noise exposure levels. Thus, the NRR (SF) is subtracted from the A-weighted noise exposure to provide the protected exposure level:

Protected dBA = unprotected dBA – NRR(SF).

If the C-weighted noise exposure level is used, a 3-dB adjustment is made to account for predicted differences in the A and C levels (recent re-evaluations of the noise databases that were used to developed the NRR (SF) found the A- versus C weighted difference to be 3 dB, not 5 dB and not 7 dB).

Protected dBA = unprotected dBC -3 dB – NRR(SF).

Where can I find the NRR(SF)?

The adoption of the initial version of ANSI S12.6 in 1997 as the standard that replaced ANSI S3.19-1974 did not change the regulatory requirements that all protectors sold in the United States be labeled with the NRR as described above and obtained by testing according to the experimenter-fit method of ANSI S3.19-1974. After ANSI 12.6 was adopted and ANSI S3.19 was rescinded, many hearing protector manufacturers began testing their products in accordance with Method B, the subject-fit method. However, only a few manufacturers have released the data. As other jurisdictions outside of North America have started to demand data from testing procedures similar to Method B of ANSI S12.6, many companies have complied. The NRR(SF) is used in Brazil, Australia, and New Zealand. Every HPD sold in Brazil is tested by an approved Brazilian laboratory by Method B of ANSI S12.6-1997 before the HPD may be sold in Brazil. Australia and New Zealand require every HPD sold in those countries to have been tested by Method B and then labeled accordingly with the NRR(SF), but the testing may be done by a laboratory anywhere.

A search of the Internet or direct inquiry with the company may result in access to Method B data and a value similar to the NRR(SF). The NIOSH online Hearing Protector Device Compendium lists most of the HPDs sold in the United States and shows the NRR(SF) for many of them. The Compendium also lists the Internet website for almost all the manufacturers, which may provide more information.

Can I legally use the NRR(SF)?

Yes. OSHA has recognized the NRR(SF) as an alternative the NRR as another way to apply a safety factor to the NRR.

If you are considering two devices, one of which has both an NRR and NRR(SF), select the device with the NRR(SF) and apply it to the equations above to determine if it can provide adequate protection.

The best value for protected level is between 70 and 80 dBA. A protected level of less than 70 dBA indicates potential over protection. A person who is overprotected may be isolated from the larger acoustic environment, unable to hear warning signals and fellow workers. As such, the overprotected worker can be a safety hazard. There are reports of workers being injured and killed because they were unable to hear warning signals or the sound of approaching vehicles because they were wearing HPDs that provided too much attenuation. The primary complaint that workers have reported about used HPDs are that they can’t hear fellow employees talking to them and that they can’t hear their equipment. It isn’t unusual to see a worker lift an earmuff cup or remove an earplug to talk with a fellow worker, and then replace it, a type of action that undoes the effectiveness of the HPD. Carefully selecting HPDs to avoid overprotection could also ameliorate the hazard potentials and worker attempts to work around using HPDs.

If the protected value is above 80 dBA, the worker will be under protected. Under protection can result in the development of NIHL despite using the HPD.  NIHL is insidious. It starts gradually and will generally go unnoticed until the hearing loss begins to interfere with communication. NIOSH’s definition of material hearing impairment (Franks, et al., 1998) is such that a person can suffer a change in hearing up to the point of developing a material impairment without noticing any change in day-to-day auditory function. Beyond that point, the hearing loss becomes an impairment. NIHL will usually cross the line from loss to impairment within the first five years of exposure. It is often observed that under protected workers develop NIIHL.

Any hearing loss prevention program that relies upon the NRR(SF) instead of the NRR and insures that workers are neither under or over protected will be successful in preventing NIHL and will have no problems with OSHA nor another other regulatory agency.


References

American National Standards Institute. (1974) American National Standard for the Measurement of Real-Ear Hearing Protectors and Physical Attenuation of Earmuffs. ANSI S3.19-1974, American National Standards Institute, New York, NY.

American National Standards Institute. (1997) Methods for Measuring the real-ear attenuation of hearing protectors. ANSI S12.6-1997 American National Standards Institute, New York, NY.

Berger, E.H., Franks, J.R., and Lindgren, F., International Review of Field Studies of Hearing Protector Attenuation, In A Axelsson (Ed), Scientific Bases of Noise-Induced Hearing Loss, Chernow Editorial Services, Inc, New York, 1996

Environmental Protection Agency. (1979). 4 0 CFR Part 211 – Product noise labeling, Subpart B – Hearing protective devices. 44 Federal Register 56139-56147.

Franks, JR. Merry, CJ Stephenson, MR, Themann, CL, Prince, MM, Smith, RJ, Stayner, LT, and Gilbert.SJ (primary authors) Chan, HS (document manager). Criteria for a Recommended Standard: Occupational Noise Exposure, Department of Health and Human Services, Public Health Service, Centers for Disease Control, National Institute for Occupational Safety and Health, DHHS (NIOSH) 98-126, Cincinnati, OH (1998)

Johnson DL and Nixon CW (1974) Simplified methods for estimating hearing protector performance. Sound and Vib 8(6):20-27.

Kroes P, Fleming R; Lempert B. (1975). List of personal hearing protectors and attenuation data, NIOSH Technical Report, HEW Publication No. (NIOSH) 76-120.

National Institute for Occupational Safety and Health (2016) Hearing Protective Device Compendium. https://www.cdc.gov/niosh/topics/noise/hpdcomp/.

Royster LH. (1995). In search of a meaningful measure of hearing protector effectiveness; Recommendations of the NHCA’s task force on hearing protector effectiveness. Spectrum 12(2):1, 6-13.

U.S. Department of Labor, Occupational Safety and Health Administration. (1983). Occupational Noise Exposure: Hearing Conservation Amendment; Final Rule. 48(46) Federal Register 9738-9785.

U.S. Department of Labor, Occupational Safety and Health Administration. (1983). 29 CFR 1910.95(b)(1), Guidelines for Noise Enforcement; Appendix A.

U.S. Department of Labor, Occupational Safety and Health Administration. (2016). OSHA Technical Manual: https://www.osha.gov/dts/osta/otm/new_noise/index.html

[i] Time Weighted Average –The permissible exposure limit (PEL or OSHA PEL) is a  legal limit in the United States for exposure of an employee to a chemical substance or physical agent such as loud noise. A PEL is usually given as a time-weighted average (TWA), A TWA is the average exposure over a specified period, usually a nominal eight hours. For noise, the PEL is a TWA8 of 90 dBA with an excursion limit of 115 dBA. The TWA involves a trading ratio of time and intensity, which for noise is 5 dB so that the allowable exposure time doubles or halves as the sound level decreases or increases by 5 dB.


These articles were written for ProtectEar by Dr. John R. Franks, former Chief of the Hearing Loss Prevention Section of the Department of Health and Human Services, U.S. Public Health Service, Centers for Disease Control and Prevention, National Institute for Occupational Safety and Health, Cincinnati, OH

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NIOSH HAS DEVELOPED A SOUND LEVEL METER MOBILE APP DESIGNED TO MEASURE NOISE EXPOSURE IN THE WORKPLACE.

February 1, 2017

 

NIOSH has developed a sound level meter mobile app designed to measure noise exposure in the workplace.

The app, available for Apple devices, provides noise exposure metrics that are of “importance for proper occupational noise measurements,” NIOSH states in a Jan. 17 blog post. NIOSH is collaborating with other agencies to develop an Android version, but the agency stated that it may verify the app only on selected devices because of the large number of available Android devices and models. The project would begin when funding becomes available.

The app supplies instantaneous sound levels in A-weighted, C-weighted or Z-weighted decibels, as well as parameters intended to aid with lowering occupational noise-induced hearing loss. Users can save and share measurement data and receive general information about noise and hearing loss prevention.

NIOSH recommends using the app with an external microphone and acoustical calibrator for better accuracy. The app is not intended to be used for compliance or as a substitute to a professional sound level meter or a noise dosimeter, the agency cautions.

In 2014, NIOSH researchers examined nearly 200 sound measurement apps. They found that most available apps are designed for the casual user and do not have the accuracy and functionality for occupational noise measurements, according to the blog post.

NOISE AND HEARING LOSS PREVENTION

 Close-up of downloaded Sound app.

The NIOSH Sound Level Meter mobile application is a tool to measure sound levels in the workplace and provide noise exposure parameters to help reduce occupational noise-induced hearing loss.

Key Benefits

  • Raises workers’ awareness about their work environment
  • Helps workers make informed decisions about the potential hazards to their hearing
  • Serves as a research tool to collect noise exposure data
  • Promotes better hearing health and prevention efforts
  • Easy to use