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Loud, Louder, LOUDEST!

David Kennedy • July 2019Tech Feature • July 15, 2019

Much has been written about appropriate sound levels for airplanes, concerts, races, sporting events, shooting ranges, workplaces and worship services. I sometimes choose a simple sound pressure level metering technique because it’s an easy way to take an average reading of the overall dB level of an event. However, the reading from a sound level meter does not correlate well to human-perceived loudness, which is better measured by a loudness meter. Wikipedia has an excellent primer on SPL meters, at www.wikipedia.org/wiki/Sound_level_meter.

Due to a formal education in record production along with P.A. system design, I understand that contemporary/rock music is not about capturing the authentic sound of instruments, as compared to audiophiles wanting high-fidelity (realistic) sound of an orchestra or jazz ensemble. I suspect that I’m in the minority as a sound engineer who studied classical and jazz music, thus I know what the authentic sound of instruments are, and I have sensitive hearing, so pop concerts can sometimes be an unpleasant experience for people like myself. Poor sound EQ or directional realism causes cognitive dissonance stress due to contradictory information. Loud sounds and noises are startling to most people, and even painful.

The World Health Organization did a study in middle- and high-income countries; they found that nearly 40 percent of all teenagers and young adults put themselves at risk for noise-induced hearing loss (NIHL) with damaging volumes at entertainment venues.

NTi Audio’s XL2 sound level meter can interface with Projector PRO software, forming a complete system for professional loudness monitoring and logging.

‡‡         Highly Sensitive People

Some people are highly sensitive people (HSP.) The most common hearing problem people experience is hearing loss and a reduction in the ability to hear conversation, especially when in a crowded room with lots of background noise. Less common is a condition called hyperacusis, where sounds are perceived as louder than they actually are, and uncomfortably/painfully so. Not all people are extroverted and not all sound techs are ex-rockers, thus not all people at concerts and worship services are adrenaline junkies, nor have hearing damage. Some people don’t like the sound as loud (for many reasons). Females are even more sensitive to high-frequency distortion and upper-mid frequencies that are too loud in the mix.

‡‡         HF Distortion

While mid-range EQ that is too high in level can be an issue, myself and several people I know have more of a problem with high-frequency distortion and over-powering bass. Have you noticed how many pro sound loudspeakers and line-arrays sound harsh — like someone screaming at you? EQ cannot completely eliminate this time-domain issue. Most of the harsh/distorted sound is coming from the upper-mid and HF harmonics exiting the HF driver — often originating from titanium diaphragms used in many HF compression drivers. For more options regarding HF driver construction, check out this page on my website: www.line-arrays.com/non-ti-hf-driver-options.html.

Distortion can also be caused by improper gain structure. For example, clipping (over-powering) a wireless microphone, or a “hot” mic clipping a console input. Digital components are especially vulnerable to clipping of their inputs.

This brings me to my next point: What if the sound isn’t “clean”? In other words, what if it’s distorted? Without body-shaking bass, we’re not sure if we’re really even at a rock show. Do worship services need to be like a rock concert/show? Are we trying to put people on an emotional roller coaster with loud sound?

As an analogy, many dump trucks have a sign on the back of them, warning following cars to stay back — so as not to be responsible for broken windshields from flying debris. Many venues meter the SPL in the back of the room (where the SPL may be safe), but of course, it’s much higher in the front of the venue. So perhaps high-SPL venues should post a similar warning sign near their speaker arrays — especially ground-stacked systems — to reduce complaints from naive patrons that are too close to the loudspeakers.

‡‡         Fear of Loud Sound

To an extent, the fear of loud noises is inherent in humans. Since the dawn of humanity, any new, sharp or loud sound would drive humans to take cover in order to keep themselves safe. A surprising loud noise, for many people, is likely to trigger fear, and/or a primal fight-or-flight mode, especially when they occur in an environment where they would not be expected. Imagine shopping through a department store and hearing a loud crashing sound around you. Everyone in the store would flinch, their heart would begin to race and they would immediately look for the reason behind the noise before returning to shopping.

Everyone reacts differently to different sounds, even among members in a single household. Some might suffer from migraines, others may experience post-traumatic stress disorder. Just as one person is better at certain sports than others, in the same manner, the ability or inability to withstand loud sounds and noises differs from person to person.

Phonophobia is the fear of loud noises and sounds, which can cause anxiety attacks or severe migraine headaches. A phonophobic person placed in the above situation may suffer from an anxiety attack — or nausea — and have to leave the room.

SureFire EarPro EP3 Sonic Defenders

‡‡         Protection, Just in Case

Just before completing this article, I was out shopping and decided to look for some new ear plugs that were better than the cheap/generic foam type, to use at a dance club and in a rock ‘n’ roll church service over the weekend. I did not have time to search and ship ear plugs from a specialty supplier online, so I stopped by my local Walmart and bought the best earplugs that they had on hand (only $15). I found some SureFire EarPro EP3 Sonic Defenders earplugs (www.surefire.com) with removable filter caps, which can be inserted for additional protection, and feature retention rings to lock the earplugs in place, along with a lanyard and carry case; they are also compatible with radio communication systems. The EP3’s come in three sizes (S/M/L), carry a stated Noise Reduction Rating of 24 dB (with filter caps inserted) and are available in clear, black and orange colors.

When the ear plug caps are in the closed position, they cut the HF (high-frequencies) too much, reducing the clarity excessively (like generic foam ear plugs), but the open position of the ear plugs provided just enough roll off of the HF to reduce excessive sibilance (HF distortion) to a comfortable-Goldilocks level for my liking, in both applications! As an added bonus, I found that the EarPro EP3 ear plugs did a good job of reducing the annoyance of excessive sibilance in a standard/typical cinema sound application (Sci-Fi movie), while maintaining perfect speech intelligibility.

I was even able to have enough clarity in the cap open position to leave the EP3 ear plugs in place for the pastor’s sermon (dialog), to reduce sibilance. But it made me wonder if churchgoers should be notified (on the lobby sign) when picking up their free foam ear plugs, to take them out during the dialog portions of the service, so they can clearly understand speech (or better yet, I suggest better concert earplugs).

Many people suggest using earplugs. Generic-foam versions are for noise control, but muffle the sound too much for music. Today, more than a dozen concert (or Hi-Fi) earplugs are available that offer fairly linear attenuation for a more flat frequency response, providing better sound quality for music. BestReviews, dancemusicnw, earbudsaddic, earplugsguide, headphonescompared, ishootshows, studiogearexperts and systemofyoursafety all have online earplug info/reviews and/or buyer’s guides of numerous earplug options. The www.allearscampaign.com website has more info on earplugs in its “Ultimate Guide to Ear Plugs.”

EarDial earplugs include a companion app indicating suggested listening times when wearing the protection.

EarDial (www.eardial.com) has the world’s first invisible earplugs with a companion mobile app. Besides music fans, the EarDial HiFi Earplugs are intended for motorcyclists, musicians, DJs, venue staff (bartenders, bouncers, etc.) and anyone that wants to hear clearly and safely in a loud event, like concerts, music festivals, nightclubs, sport events, gyms or cinemas. The $27 EarDial package includes a compact aluminum keychain case and a companion mobile app informs the user the approximate sound level pressure in the area and how long one can stay at that level without risk of hearing loss. The plugs are said to offer fairly flat broadband attenuation and have a Noise Reduction Rating of -11 dB.

Apple’s upcoming watchOS6 operating system for its Apple Watch includes Noise, an SPL measurement/warning app.

Last month, Apple released beta copies of the upcoming watchOS6 operating system for its Apple Watch, which will include a Noise app that detects loud sound and notifies the user when it thinks you may be at risk for hearing damage. The Noise app uses the watch’s built-in mic to measure dangerous sound levels. Noise will automatically notify you if the sound around you is over 90 dB. The app doesn’t record or save any audio (preserving privacy). The new OS is slated for fall 2019 release and will be offered only for Apple Watch Series 4 models.

SPL measurement apps for smart phones have been around for some time. However, the concept of mixing a show surrounded by a sea of Apple Watch-wearing audience members who may suddenly feel empowered with the need to inform the FOH engineer about excessive levels — without considering other factors, such as ambient background noise of screaming fans — may bring up some encounters that could be “interesting,” to say the least. Oh well, technology marches on…

The CDC has been active in providing materials that educate consumers about loudness-based hearing loss.

How Does Hearing Loss Happen?

There are three types of hearing loss:

• Conductive (interferes with the way sound waves travel through the ear)

• Sensorineural (results from damage to the ear or nerves within the ear), and

• Mixed (a combination of the two).

Common causes of hearing loss include damage to the inner ear; buildup of earwax, dirt or other substances; ear infections and ruptured eardrums. Exposure to loud environments can exacerbate hearing loss. These graphics from the U.S. Center for Disease Control (CDC) indicate some entirely preventable ways in which hearing loss can occur from environmental factors.

Loud noise levels can overwork the cilia (hair cells) within the inner ear’s cochlea, which can cause these cells to die.

David Kennedy operates David Kennedy Associates, specializing in the design of architectural acoustics, AV systems and custom loudspeaker arrays. Since 1980, he has designed more than 300 auditorium sound systems, including churches, schools and performing arts centers. Visit him at www.line-arrays.com.

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