Great News!

I started college as an ASL major and had a vested interest in learning as much as possible, so I came into ISU with quite a knowledge base of Deaf Culture and American Sign Language. I was able to petition out of the Deaf Culture 100-level course but was encouraged by my advisor to take Deaf Culture 256: Culture and Community.

But after half the semester, I felt I had learned nothing new and decided to drop the course and petition it.

My first petition was denied due to lack of documentation of my knowledge, so I re-petitioned with an essay I'd written on the juxtaposition between Disabled and Non-Disabled status in the Deaf Community, especially in relation to the Americans With Disabilities Act. Apparently it was still not enough and Dr Turner asked me to take the final exam from the course.

I was livid after taking the exam, because so much of the information was proprietary -- it was not in the textbook (Journey Into the DEAF-WORLD by Ben Bahan et. al) and therefore not readily available to me. I felt like I had been cheated somehow.

But today I received news that Dr Turner has accepted my petition and I won't have to take the course. This is great news! Now I'll have that extra room in my schedule to fill with psychology courses and research. This fall, I'm in a research methods psychology course and I'm very excited about it.

Anyway, just thought I'd share my excitement! I feel vindicated, almost.

More Bad News

I wore the dosimeter for a full day. Drive to work, work-day, and drive home. I didn't even hit 25% dose. I'm beginning to think the dosimeter is broken.

It might be important to note that when I was wearing headphones at work (during my music listening/PBS viewing) and at home (during my Modern-Warfare 2-ing), I couldn't use the dosimeter. This is good and bad -- it is good because it allows for any significant findings to be attributed to work conditions, bad because I can't factor everything in and get the true picture.

I will be purchasing a Sound Level Meter in the near future so as to have as much information about my auditory surroundings as possible. Until then, I will be putting the dosimeter on the shelf and buckling down on my secondary research so I can meet my deadline.

I'm Not Broken!

I've known about Jung's personality test for a while, but the last time I took it was in high school. I don't remember what I got, but I reckon it was different than it is now. I feel like I've grown into myself over the last several years and the results I got are almost spot-on.

I turned out to be an INTJ. An Introverted iNtuitive Thinking Judging personality. I've included my favorite parts of what that means below. The relationships part is what surprised me the most and made me very happy to discover. I'm not broken, I'm just an INTJ!

"When it comes to their own areas of expertise -- and INTJs can have several -- they will be able to tell you almost immediately whether or not they can help you, and if so, how. INTJs know what they know, and perhaps still more importantly, they know what they don't know."

"Personal relationships, particularly romantic ones, can be the INTJ's Achilles heel. While they are capable of caring deeply for others (usually a select few), and are willing to spend a great deal of time and effort on a relationship, the knowledge and self-confidence that make them so successful in other areas can suddenly abandon or mislead them in interpersonal situations. This happens in part because many INTJs do not readily grasp the social rituals; for instance, they tend to have little patience and less understanding of such things as small talk and flirtation (which most types consider half the fun of a relationship). ... Perhaps the most fundamental problem, however, is that INTJs really want people to make sense. This sometimes results in a peculiar naivete', paralleling that of many Fs -- only instead of expecting inexhaustible affection and empathy from a romantic relationship, the INTJ will expect inexhaustible reasonability and directness."

"Decisions come easily to them; in fact, they can hardly rest until they have things settled and decided. But before they decide anything, they must do the research. Masterminds are highly theoretical, but they insist on looking at all available data before they embrace an idea, and they are suspicious of any statement that is based on shoddy research, or that is not checked against reality."

As an INTJ, I highly value accurate truths, even if they don't benefit me. I remember as a kid even correcting my friends because they tailored the truth to benefit themselves. Ugh.


More journals are coming. I found some interesting pieces on potential conditioning and toughening of the auditory system in lab animals but I want to read all of it before commenting and summarizing.

Diversions

When I make a list of the few non-necessities that I couldn't live without, one of them is always 'diversions'. By that, I mean the things that make me a multidimensional person.

I've been taking photos part-time as a self-sufficient hobby since Sophomore year of high school, and while my work isn't as artsy as I would like it to be, it's definitely commercial which works in my favor. I mostly do senior portraits, but in anticipation of doing my first paid wedding gig outside of my family, I volunteered my services at my wedding-partner's friend's wedding.

The results reminded me once again that I can't let myself get too sucked into one thing. I need to keep photography around as a nice diversion and to prove I'm more than just my collapsible file folder.

Some Answers! (Hopefully.)

So I have grown up in an interesting financial situation. My family makes plenty of money, but most of it gets spent on medical bills despite our great insurance. My father had at least one surgery on his neck and I've had two separate surgeries for my tonsils and my adenoids (thank you, Dr. Van der Graaf, for providing cold, faceless, incomplete surgeries), along with medications and such along the way and my year+ of therapy for my arachnophobia.

In short, my parents didn't have any money saved up for me to go to college, but they make too much for me to get any free government assistance, so they've been taking out Parent Plus loans to pay for my tuition and living expenses. The thing about Parent Plus loans is that they tack on lots of interest.

I'm mostly independent. My parents still help out with my gas and give me a small allowance each month, but I work and live on my own, and I have since moving out in 2007. So lately, I've been wondering about declaring independent status on my tax forms, because it may help me out with getting legit aid from the government.

Because I have no idea who to ask, I decided to ask "Judge Josh" from www.givemescholarships.com what he thinks the pros and cons of declaring independent status would be.

One obvious one is that I don't think I'd be able to be on my parents' insurance, but even at that point I'm not positive. I'm still young enough to count, and I'm in school. I need some guidance from someone who knows the system.

Hard At Work

Here is the second dose (get it?) of my summaries. This puts me up to date for all the articles I have read so far. Time to gather more! :)

1. Recreational noise exposure and its effects on the hearing of adolescents. Part II: Development of hearing disorders. Ester C Biassoni et al. Int'l Journal of Audiology (2005)

This study was a follow-up to the one in Argentina looking at the undue amount of hearing loss in young adults. As much as has been found about NIHL, the author writes, “...the auditory system is much more adaptable than currently assumed, therefore it recognizes the danger of intensive sound and adapts to the situation by reducing its sensitivity.” Even so, the research shows that young adults are exposing themselves to extreme noise in settings such as discotheques and concerts.

An interesting point that this study raised was that there is data which indicates, “...that the supersonic components of the music spectrum may have substantially contributed to the damaging effects of the exposure.” Sound we aren't even measuring could be greatly-affecting how much we're damaging our hearing. This allows for the possibility of sub-damaging levels of noise to still affect us.

Later on, the authors explain that the group with the worst thresholds (those deemed to have 'tender ears') exhibited elevated thresholds in the 8000-16000Hz range, extending lower into the conventional range of hearing. This, the authors state, “...could act as an early predictor of future development of hearing loss in the speech-understanding frequency range,” which is of most concern to clients.

Knowing that this loss happened between ages 14 and 17, this study provides evidence for the need to test students before they are pushed out into the 'real world,' when they can still gain help through the school system. There is also evidence for a hearing conservation (hearing loss prevention) program in the schools, perhaps blended into biology courses. It would also be helpful to limit the noise level in loud places, such as concerts, 'discos'/bars, etc. Even reducing noise levels at rock concerts from 117 dBA (equivalent to the discotheques in the other studies) down to 106 or 103 dBA would be helpful, due to the 3 dB exchange.

2. Characteristics of the audiometric notch as a clinical sign of noise exposure. David McBride and Sheila Williams. Scandinavian Audiology (2001)

This study was an evaluation of 1,600 audiograms (634 noise-exposed employees, each with two ears), the purpose of which was to investigate variability in the noise-induced hearing loss 'notch'. Traditionally, the first sign of noise-induced hearing loss is at approximately 4KHz, where the audiogram develops a small notch that gets deeper and wider as the damage continues. The authors chose three raters (an otolaryngologist, and audiometrician, and an occupational physician) to interpret the audiograms and determine whether or not the dip is related to noise exposure. The three features the interpreters looked for were the frequency at which it occurred, the depth, and the shape of the curve.

I found an unexpected piece of information while reading this article. The first rater (the ENT) classified 26% of the audiograms as NIHL, whereas the occupational physician classified 68% as NIHL, with more notches identified at every frequency and no specific criterion for depth or shape in mind as he/she rated. This is evidence for why occupational audiologists are needed as opposed to unrelated professions which are slated for an audiologist's job. I think this would be an important statistic to show in advocacy situations. Not only are we better-trained, we can save the companies money by not over-referring!

Either way, the high variability suggests that audiometric shape cannot be used as a method for diagnosing noise-induced hearing loss. As Alberti (1997) states (as quoted by the authors), “This supports the contention of Alberti, who has long been of the opinion that audiometric shape may only be a guide, and not a major diagnostic factor for, for NIHL.”

3. Supplement: Program for the Conservation and Promotion of Hearing Among Adolescents. Mario R Serra et al. American Journal of Audiology (2007)

This supplement was another piece in the “Recreational Noise Exposure and Its Effects...” done in Cordoba, Argentina and involving 14-year-old students in a semi-longitudinal study over three years. As the authors state, there were two noticeable findings: “1. There was a higher tendency of more sensitive ears to be affected at an early age... 2. The efficacy of audiometry in the extended high-frequency range was an early predictor of hearing loss.” The latter is probably the most important clinically, but the former is important to keep in mind as we discuss the issue of noise exposure in young adults. Some sources state that young ears are less fragile, and others state that fragile ears are more susceptible while young.

This article taught me a few things about noise exposure that I hadn't quite learned yet. Namely, the authors explain, “While TTS typically resolves within a few hours or a day after exposure, there is no agreement among researchers whether repeated TTS bears a risk of permanent threshold shift.”

4. Effect of a hearing protection campaign on the discotheque attendance habits of high-school students. Viktor Weichbold, Patrick Zorowka. Int'l Journal of Audiology (2003)

This was an ambitious study with high hopes that unfortunately failed to deliver. The goal was to pilot a hearing loss prevention program in six high schools in the Italy/Austria area called “PROjectEAR” and hope that it changed young people's opinions about hearing protection and loud noise. There were four 45-minute sessions spread over 3 days which presented several different approaches to protecting one's hearing. An interview was conducted post-campaign with 136 students although all of the students in the schools participated.

While the percentage of students who attended discotheques frequently lowered from 34% to 24% after the campaign, statistical analysis does not support the idea that there was a significant change. The authors state that, “..the changes observed in our sample may be due to the random variation rather than to a systematic effect of the hearing protection campaign.” In addition to that discouraging finding, less than 4% of the students took the advice to use ear plugs or other hearing protection in the discos.

The authors explain that there is no control group for this study because there was too much information-sharing between students participating and those were not. Also, although, “...the campaign had no important effect in inducing hearing-protective behaviors in pupils when attending a discotheque,” one of the other studies found that students were willing to take more 'regeneration breaks' after the program and have the discotheques reduce their sound floor, so perhaps that is an area to target.

A quote I really liked that I wanted to include for the sake of aesthetics is, “At this point, a tragic irony becomes obvious. The pupils experienced the negative effect of bad hearing on communication when they tested earplugs for hearing protection in the discotheque. Being annoyed about the impaired communication, they dismissed the earplugs.”

5. Noise exposure levels from personal stereo use. Warwick Williams. Int'l Journal of Audiology (2005)

This study aimed to look at worst-case scenarios of personal media players, such as listening in the presence of relatively loud background noise. In this case, the background noise was approximately 73.2 dB, but varied from 71.1 to 76 dB. Fifteen females and forty males were asked to participate in the study (mean age 23.6 years), which meant allowing their headphone output to be measured and filling out a short survey of their listening habits. The average volume turned out to be only 79.8 dB, but approximately 25% of the population was still estimated to be “at-risk,” by listening to music over 85 dB.

Also of note is that the males (the larger group) listened to their music at 80.6 dB on average as opposed to females ,who listened at 75.3 dB. Perhaps if more people were studied, this average would sneak up?

The authors state in the conclusion that, “While some individuals do expose themselves to significant risk of noise injury by using earphone levels at high settings, the data collected in this study does not indicate that for the majority of typical users there is a significantly increased risk of hearing loss due to PSP (personal stereo player) use alone.” Unfortunately, those people who may lie on the boundary line are at risk in other areas of their lives because people who listen to their music loudly are more likely to listen to their television loudly, etc.

6. Effects of Exercise and Noise on Auditory Thresholds and Distortion-Product Otoacoustic Emissions. Shannon Hooks-Horton et al. Journal of American Academy of Audiology (2001)

This study isn't totally connected to the research I'm doing, but I found it hilarious that the authors actually address, “It is also the case that ovarian and contraceptive cycles may play an additional role in TTS shift in females, however this factor was not controlled in the present study,” and that the TTS shift for ovarian cycles was actually investigated by two different studies: Petiot and Parrot (1984) and Hori et al (1993). How funny is that!

Oh, and by the way, the authors found that there is no significant connection between exercise and noise-susceptibility.

It Begins...

So for the last 6 years or so, I have struggled with an unidentified infection which runs on a cycle. At first, it was a 3-4 week cycle and included very significant strep-like symptoms. In 2008, I underwent a tonsillectomy which was supposed to 'fix' me. It did for 6 weeks, but then my infection returned on a 6-week cycle. The symptoms weren't always as bad, and if I slept 10 hours a night for several nights prior to the infection, I could delay it a day or two and speed up my recovery but they were always inevitable. My third (or fourth?) otolaryngologist decided to go ahead and take my adenoids, which had somehow been left by my first otolaryngologist. I'm not surprised. I saw him once and couldn't pick him out of a lineup. It was an assembly-line tonsillectomy. The adenoidectomy made for an awful recovery but I made it, and this time my infections weren't even delayed. They still happen every 6 weeks, almost to the day. My last infection ran from May 23 through May 31 and it looks like Day 1 is here since I popped a 99.6-degree fever over lunch.

I found it important to share because it explains why I will probably take tomorrow off and spend it sleeping/reading/updating.

Now, the much-anticipated summary of several of my articles so far...

1. Estimated Leisure-Time Noise Exposure, Hearing Thresholds, and Hearing Symptoms of Finnish Conscripts. Lt Col (Med) Toivonen. Military Medicine (2005)
This article didn't provide a whole lot of useful information aside from a formula for weighted weekly and lifetime exposure to noise. Over 1000 young adults were in the study (obligatory military service) and the most frequent activities were, "watching television, listening to a home stereo, and going to night clubs and pubs." In addition, "The conscripts considered festivals and concerts, shooting firearms, playing in a band, and using tools indoors and outdoors to be the 'loudest' leisure-time activities." What's unfortunate about this is that those activities are more frequently outdoors and done on a more short-term basis as opposed to home stereo systems and television sets which are more frequently indoors and still set to a relatively high level.
Another scary statistic is that, "When the group with actual hearing loss was compared with the self-reported hearing loss, 79% of the conscripts with hearing loss did not know or disclaimed their hearing loss, and only 18% knew their hearing was not normal." For this study, 'loss' was defined as beginning at thresholds elevated at least 20dBHL.
One other thing I felt worth mentioning was that the author stated, "On a whole, the young adults were more active in several noisy activities and used more hours during the week in noise activities than the adults did." As the other articles have pointed out, young ears are less fragile than 'old' ears, so if the young ears are those exposed to this extra noise, then it shouldn't affect them much. But where does it end? At what point do we say, "That's just wanton disrespect for your ears"?


2. Can a hearing education campaign for adolescents change their music listening behavior? Viktor Weichbold and Patrick Zorowka. Int'l Journal of Audiology (2007)
This article, another foreign one based in Austria, was aimed at educating young adults. The subjects were those who attend discotheques, rock concerts, noisy pubs/parties, and those who listen to loud music or play in a band. They held classes for the students, "...four 45-minute sessions spread over three days and includ[ing] a variety of didactic approaches to make the topic of hearing conservation as attractive as possible: multimedia presentations... demonstrations of ear protection devices and hearing aids, role-play, questionnaire survey, creative group work... and a discussion with a hearing-impaired person or tinnitus sufferer."
The program offered Regeneration Breaks as an option instead of dampening ear protection... just taking a break and sitting in a quiet area before returning to the noise. Those breaks seemed to be much more popular than wearing earplugs. After the campaign, the majority of students had changed their opinion about the loudness levels in the discotheques, and believed they should be reduced, whereas the minority then regarded them as fine. The authors explained, "This is an im0portant result of the campaign (hopefully) -- not because it will motivate adolescents to go to the discotheques less frequently or to use earplugs from now on -- but because it will make them open-minded towards sound level reduction in discotheques." And then later, the authors suggested possible financial subsidies be offered to clubs which will voluntarily limit their sound level. I thought that was a fantastic idea!

3. Age and noise-induced hearing loss. Esko Toppila et. al. Scandinavian Audiology (2001)
This study looked at age and noise exposure as factors in high-risk occupational noise environments. The goal was to determine significant factors to susceptibility. What the researchers found was that age is the most-correlated factor, but also significant were the factors of elevated cholesterol levels and use of analgesics (greater than 20 pills per month). Unfortunately (or maybe fortunately in the larger picture), the article states that, "The inner ear in older subjects seems to be more vulnerable to noise than those in younger ones." This is good for young people in the larger picture but it puts a cramp in the style of this research because it insinuates that young people can afford to ravage their ears when they simply can't!


4. Young people: Their noise and music exposures and the risk of hearing loss. Thais C Morata. Int'l Journal of Audiology (2007)
This editorial piece discussed both sides of the young adults and noise exposure argument. On the one hand, noise is everywhere and it's only getting louder. Morata states, "...ever increasing intensity levels during concerts and at nightclubs has made music exposure the most studied source of excessive sound exposure to children and youths in several countries." But Morata also intimates that some researchers believe that there is a, "...possibility of a toughening protective effect of such exposures..." (Fleisher and Muller, 2005, an article I'd love to read).
Morata cites another study by Fleisher and Muller that found that, "...orchestra musicians, despite their exposure, had the best hearing thresholds among several occupations and non-exposed groups."
But I wonder, are good thresholds the chicken or the egg? It could be that people who are in orchestra are more likely to have better thresholds in the first place and/or tougher, more responsive ears which bolsters their talent. The author also mentions that, "The prevalence of high frequency hearing loss has decreased over the twenty-year period, while the prevalence of audiometric 'notches' remained constant... Is it too soon to detect the effects of more recent technology? Possibly yes, since the findings from the study do not demonstrate any systematic, measurable effect on entrance audiograms."
I agree that it's too soon to tell. Twenty years is a long time, I wonder what the statistics would show if the author had looked at only the last five or ten years, when the 'bigger, badder, louder' culture started to arise. Lastly, a positive finding, "This evidence suggests that long term school-based programs can effectively increase the use of hearing protection among students, and sheds some light on approaches that ought to be considered for increasing awareness of the value of hearing and means of preventing disorders." This gives me hope that if we discover something that can be utilized in a long-term prevention program, students may be affected!

5. Music exposure and Audiological findings in Brazilian disc jockeys. Lorayne Santos et. al. Int'l Journal of Audiology (2007)
This article was mildly distressing. Forty Brazilian disc jockeys were studied in their work environments, which happened to be 93.2-109.7 dBA for approximately 8 hours at a time. 74% of the DJs reported tinnitus, and only 33% indicated that they used hearing protection at all. 27% of the participants already had thresholds above 25 dB and TEOAE testing showed that their exposure was dangerous. However, despite the information, the authors reported, "Even when the DJs learned about the test results, they indicated that they did not think the situation needed any change. They indicated they would like to learn more about flat attenuation ear plugs, but did not anticipate starting to use them." That is distressing because one would imagine that in an environment where hearing is so important to the occupation, employees would take steps to preserve what they have left. Will young adults feel the same way about their exposure, seeing that they are not exposed to quite as much noise as Brazilian disc jockeys?


6. Influence of music and music preference on acceptable noise levels in listeners with normal hearing. Susan Gordon-Hickey and Robert E Moore. Journal of American Academy of Audiology (2007)
This article described the ANL (Acceptable Noise Level) as the "maximum level of background noise that an individual is willing to accept while listening to speech." A previous article had listed music as the least-accepted noise, requiring 14.47 dB of gain for speech before listeners reported being comfortable with listening to a long narrative without getting lost. For this study, however, participants reported being comfortable at a significantly higher level of music (lower S:N ratio) at 6.25 dB gain of speech over music.
Some of the discussion hinted that the ANL may differ across genres based on preference or lyrical content, or other factors. The previous study (Nabalek et al, 1991) had used Muzak whereas the present study used contemporary rock music. Also worth mentioning is that the present study utilized young adults (mean age 23.54 years) and stated, "This group may be less distracted by and more accepting of background noise composed of music," because they're more likely to encounter background music in their lives. However, it's important to note that, "The results of this ANOVA (removing participants who recognized the music's artist/song name and redoing the statistical analysis) were the same, suggesting that familiarity may not influence ANL to music."

I hate it when news is good and bad at the same time.

First of all, my write-ups for those 7 articles (and more) are coming. I've just been spending more time reading than writing, since I have an August 15 deadline for secondary sources. I have some of them written but don't want to update too often. These write-ups are mostly for my benefit anyway.

For now, I want to address something I discovered over the weekend.
I took my (borrowed) dosimeter to the theater and elected to watch The A-Team. It was a good movie overall with a few technical errors that didn't affect how much I enjoyed it. Unfortunately, during a 117-minute film, my dosimeter registered less than 25% dose. Granted, I was in the rear-most row, but seeing how this was an action movie, I expected to reach at least 25%. Next time, I will sit in one of the forward-most rows and see what happens there. But as of now, it's looking like theaters are not a significant-enough source of noise to warrant inclusion in the study.

The good news is that these theater employees who spend all day in such an environment are not risking their ears. And like Dr. Brockett (and several other people) say, lack of significant noise exposure is just as good a result as discovering significant sources. What if music really is the largest contributor to young adults' hearing loss? Is technology the problem? (More on this when I update my articles.)

Also, I wanted to post my essay as it stands. I think I'm getting close to finishing it. You can find the file here, and a video of me reading it (albeit not the best inflection) is below.

7 more! (I've been busy.)

I read seven more articles tonight.

1. Young people: Their noise and music exposure and the risk of hearing loss. Thais C Morata. Int'l Journal of Audiology. (2007)

2. Can a hearing education campaign for adolescents change their music listening behavior? Viktor Weichbold and Patrick Zorowka. Int'l Journal of Audiology. (2007)

3. Program for the Conservation and Promotion of Hearing Among Adolescents. Mario R Serra et. al. American Journal of Audiology. (2007)

4. Recreational noise exposure and its effects on the hearing of adolescents. Part II: development of hearing disorders. Ester C Biassoni et. al. Int'l Journal of Audiology (2005)

5. Characteristics of the audiometric notch as a clinical sign of noise exposure. David McBride and Sheila Williams. Scandinavian Audiology (2001)

6. Noise exposure levels from personal stereo use. Warwick Williams. Int'l Journal of Audiology. (2005)

7. Effects of exercise and noise on auditory thresholds and distortion-product otoacoustic emissions. Shannon Hooks-Horton et. al. Journal of the American Academy of Audiology. (2001)

I will summarize and pick out important excerpts soon. I'm on information overload after so many articles in a row!

Discotheques?!

Last night, I read the first three articles of the 30 I just printed off. I've still got plenty of online journals to search, but I think this is a good start.

One of the three was just a simple article in Audiology Today, and didn't yield anything worthwhile.

However, the other two were:
"Recreational noise exposure and its effects on the hearing of adolescents. Part I: An interdisciplinary long-term study." Mario R Serra, et. al International Journal of Audiology (2005)

and

"Position Statement of the American Academy of Audiology: Preventing Noise-Induced Occupational Hearing Loss" Elliott Berger, et, al Audiology Today (2004)


The position statement provides a lot of baseline standards and data for noise exposure. A few choice experts are:
"According to the National Institutes of Health, approximately one third of all hearing loss can be attributed to noise exposure..."
I would venture to guess that this number will increase as my generation ages. I've noticed that even when my peers are made aware of the repercussions, they remain passive.

Audiologists should, "...think in terms of hearing loss prevention rather than hearing conservation."
I wasn't aware that this was the position of AAA. I like it, and I think it fits with the spirit of the research.

"The success or failure of a hearing loss prevention program, including employee buy-in, depends up on effective education and training (Berger, 2001)."
Now to the core. This excerpt will support the idea that creative implementation of the information will determine its efficacy. As I mentioned in my statement of purpose, it's not enough to just know the facts. (See next quote.)

"...education and training must consist of more than showing a film and passing out a pamphlet or it will be ineffective."



The Recreational Noise Exposure article was a semi-longitudinal study conducted over four years in Argentina with (63) male and (43) female subjects ages 14-17. The participants underwent a battery of audiological tests every year for four years, and common activities were analyzed. The study found that:
1. Their participation in musical recreational activities increased yearly.
2. The favorite musical activity for both groups was attendance at discos, especially during the last years of the study.
3. Conversely, use of personal music players was not so important.
4. Attendance at live concerts increased during the last year of the study, but it was not as frequent as attendance at discos.

The measurements inside the discotheques ranged from 104.3 dBA to 112.4 dBA, with peaks as high as 11.5 dBA. At even the lowest value, a dosimeter was used and a dose of 1600% was obtained, although the authors did not mention how long the dosimeter was used inside the building. Either way, if young people are attending those discos on a regular basis, they're sure to feel the effects.

The authors mentioned that it was, "...clear that the exposure of the adolescents to equivalent sound levels of music above 100 dBA at discos exceeds, in all the cases, the most recent international recommendations for hearing conservation in occupational environments. The difference between a worker and an adolescent attending discos once or twice a week is the recovery time between exposures. However, meanwhile, the adolescents also participate in other noisy entertainments, which must be added to the music exposure at discos."
This excerpt is essential to the exigence in our research topic. Sure, young adults may have a week between their exposure to live concert-style music (at coffee shops, bars, clubs, etc.) but during that week they're listening to loud music in their car, through headphones, going to sporting events, potentially working in noisy environments, attending movies in loud theaters, and the list goes on.

One point made in the article is that young people in Argentina were not listening to portable music on a regular basis, which I believe is directly counter to the reality in America. I would venture to guess that American teenagers are more likely to listen to portable music players than they are to attend anything equivalent to discotheques, particularly because of a lack of expendable cash these days.

Anyway, these are just the beginning of gobs of research I've got to read! I'll be reading again tonight and have an update soon.