This Article Was Originally Published On: April 15th, 2016 #Issue 18.

The Company Line

Etymotic (pronounced “et-im-oh-tik”) Research was founded in 1983 by Mead Killion, Ph.D. to “to design products that accurately assess hearing, improve the lives of those with hearing loss, protect hearing, and enhance the listening experience of musicians and music lovers everywhere.” They invented insert earphones in 1984, and their designs using balanced-armature receivers established that technology as the gold standard for high-definition earphones. Located in the USA heartland of Elk Grove Village, Illinois, their products’ roots have become a baseline for all similar products, worldwide. Their products are used by all walks of life and profession needing either hearing protection or hearing assistance. This leads us to the product we’re looking at here: the MP•9-15 Music•Pro® – first launched at the 2013 NAMM Show – and the ER•20XS Universal Fit, a July 2015 update to the 20XS, from early 2015 (which is a smaller update of their longer lived and very popular ER•20 model).

Fender Rumble 600x200

First Impressions

There are a dizzying array of hearing protection products out there, varying from simple foam plugs that cost a couple bucks (for several), all the way to these active devices, costing just under 300 clams. And that’s just talking about strictly hearing protection. I’m not including all the various brands and styles of in-ear monitors (which are designed to not only protect hearing, but ALSO plug into an audio source). I’ll refer to all the aforementioned products in my list simply as “passive ear protection.” Passive ear protection comes in various flavors of custom-fit products and universal-fit. Custom-fit requires an impression from an audiologist, just like custom in-ear monitors, whereas universal-fit employs either a foam (typically “memory foam”) or “umbrella” rubber/silicone component to hold them in your ear and make the seal. They typically have a “filter” design, which is a carefully designed set of channels to dampen sound, while attempting to avoid degrading it as effectively as possible. This is the family of products the ER•20XS falls in. They’re inexpensive, easy to use, come with a couple options for eartips, are rated at 20dB of suppression, and do a very good job of passive filtering, without destroying the quality of what you’re listening to.

The MP•9-15 Music•Pro’s completely seal your ears from the outside world when properly fitted. But instead of using passive chambering/filtering, they use a tiny microphone and speaker system with a circuit to amplify, as well as dampen, sound as needed, and do it dynamically as the environment around you changes. That’s the “active” aspect of these devices. They offer dual modes of operation: “Natural Hearing” and “Enhanced Hearing.”

A Closer Look

There’s not much to say about the ER•20XS plugs, other than they work well, and are a great value. No passive earplug is going to be completely transparent, but these do as good of a job of any of the others I’ve tried (and I’ve tried too many to list, here). I didn’t try the foam eartips, because the triple umbrella eartips worked well for me, and were what was installed by default. The MP•9-15’s come with various eartip sizes and styles (one of which is sure to fit anyone’s ear type), a nice protective case, a lightweight cord, replacement filters (and replacement tool), and a package of batteries. Each plug requires one #10 zinc air hearing aid battery, and the set comes with a package of eight batteries. These are very tiny batteries, and allow these devices to be self-contained, without having to use an outboard power pack. The downside to these batteries is they die in about four weeks after you pull the tab off, even if they’re not being used, and Etymotic’s guidance is to count on about ten days of use. They also recommend that you always have spare batteries with you. They suggest you can probably squeeze a bit more life out of them if you pop the battery door open between uses, but I’d be worried about the batteries flopping out and losing them, or, simply wearing the door out and making it loose, over time. The filters are a very small insert in the output hole (the part the eartip goes over) which helps improve the sound of the devices and also helps prevent earwax from entering the inner workings of the device. They’re replaceable if they become damaged or clogged.

The two modes of operation are selected via external switch, making it easy to change them on the fly if you’re going from one environment to another. The Natural Hearing mode basically passes the sound through until it exceeds a safe level, and after that, provides automatic gradual reduction of up to 15dB. For impact and blast type noises, however, the protection is determined by the eartip seal to the ear, which is about 35dB with the default 3-flange eartip. The maximum protection happens at about 100dB, but it actually starts suppressing mildly at about 70dB (otherwise it essentially passes all the sound through). The Enhanced Hearing mode is a bit more interesting. It’s designed to help you hear better at lower-volume levels, such as conversation, but then suppress as volume increases. The 6dB gain goes all the way up to about 75dB and flattens out about 80dB. Above 80dB, it gradually suppresses increasingly, with full 9dB suppression at (also) about 100dB. The blast protection is of course identical, as it’s unrelated to the electronic suppression.

All in all, it’s a clever design, and I’m surprised there aren’t more companies making devices like these. I’d like to see some healthy competition drive this design – and technology to support it – to the next level and possibly help reduce end user pricing at the same time … just as happens with any technology that becomes popular and widely used. Speaking of which, in today’s world, where our hearing is assaulted on a daily basis from a plethora of sources, despite the traction hearing technology already has, I’d like to see it progress even more. It bears mentioning that Etymotic also has other variations of this set, including a version called the EB15•LE BlastPLG® for military personnel.

Lasting Impressions

Etymotic suggests the MP•9-15’s are aimed at “Directors and music educators, performers, front-of-house crews, entertainment industry support staff, security personnel, and audiences.” In my experience, it depends mostly on your environment. I’m a local cover band guy, so my environment is not very dynamic – it’s pretty much just too loud all the time – so these devices didn’t carry nearly the same benefit and cost justification for someone in a much more dynamic environment, where it went from very loud to modest volume levels, a lot. The key to the value of these devices is their behavior in highly dynamic environments. If you’re just look strictly for suppression, they might not be worth the fairly healthy $299 price tag. However, if you are, you’ll likely never find another product which would provide a higher-fidelity method of hearing protection and aid at the same time. I did put myself in a few of these dynamic environments, however, and these devices do work as advertised. I guess if I had my wish, they would employ a longer-lasting battery type and have a convenient way to effectively turn them off when not in use.

If you feel that the MP•9-15’s are outside of your budget, or if you don’t feel the need for their particular benefits, then the ER•20XS passive earplugs are a great choice. They work very well, they are a great bang for the buck, and they are comfortable to wear for extended periods of time.


Manufacture:Etymotic Research, Inc.
Model:MP•9-15 Music•Pro
Made in:USA
Modes of Operation:Natural Hearing (15dB reduction), Enhanced Hearing (9dB reduction)
Battery Type:#10 Zinc Air
Accessories:Case, neck cord, ACCU•Fit eartips, batteries, cleaning tool, filter tool and ACCU•filters™
Warranty:1 Year

Manufacture:Etymotic Research, Inc.
Model:ER•20XS Universal Fit
Made in:USA
Modes of Operation:20dB of passive suppression
Battery Type:N/A
Accessories:Case, neck cord, ACCU•Fit eartips
Warranty:1 Year