Periodic Audio's Be Beryllium in-ear monitors ($300) are a high-performance, premium IEM option for anyone looking to massively upgrade their mobile listening experience. 

If you are short on time, I'll get right to the point: I've owned many headphones over the past 30+ years and these are something special. Above all, these IEMs are truly free of audible distortion and coloration. When it comes to sound quality, they are my favorite portable headphones—ever.

Having said that, which headphones any given person prefers is a matter of taste. Unfortunately, unlike regular over-ear and on-ear headphones, IEMs cannot be demoed at stores. Typically, you have to buy a pair to know if you like the design as well as sound profile of a particular model, which makes reviews and owner feedback all the more important elements in the decision-making process.

First, some background on the company: Periodic Audio makes three IEM models. Each is named after the element used for the transducer: Mg ($99), Ti ($199), and Be ($299) which stand for magnesium, titanium, and beryllium. Aside from the transducer material, the three models are practically identical—same size, shape, etc. And while I can vouch that all three models sounds good, based on my listening, the beryllium Be model offers the best performance of the three and is priced accordingly.

Periodic Audio offers three models, with drivers made of the element that gives each model its name
With its science-centric audio guru Dan Wiggins behind the actual designs, it's not surprising that Periodic Audio publishes and discusses the frequency response plots, specifications, and subjective qualities inherent to the use of each material and the design of its headphones. For example, it is a scientific fact that beryllium offers the best physical qualities (light weight, resistance to resonance) of the three materials, and that translates to better sound.

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These dynamic, single-driver IEMs are not explicitly designed for use with phones—you won't find and in-line volume control or a microphone. These IEMs are primarily meant for listening to music, not making calls. Periodic Audio IEMs have an understated look, with the only point of differentiation between the three models being the color of the logo.

Periodic's Be uses a 10mm dynamic driver, as do the Mg and Ti models. According to Periodic, the choice of that diameter was the result of balancing the tradeoffs between using a smaller driver that can be placed closer to your eardrum and a larger driver, with more surface area that can deliver more output and therefore greater dynamic range, plus lower distortion at a given output level.

Periodic Audio Be IEM specifications are impressive, especially since the company provides charts to back up the numbers. Frequency response is 12 Hz to 45 kHz, sensitivity is 100 dB at 1 mW. Power handling is 20 mW continuous, and THD is less than 1.0% with 1 mW input.


Not so long ago, I auditioned Sennheiser's $50,000 Orpheus electrostatic headphones at CanJam 2017 in NYC. That system purportedly has the lowest distortion of any music reproduction system, a quality that was surely part of the sweet sounds I experienced when I heard them. Interestingly, Periodic Audio was also there. Anyhow, I mention all this because the Periodic Audio Be IEMs remind me of the clarity of the Orpheus. Plus, that sense of total musical transparency was present even when powering the Be IEMs with my cell phone—try doing that with full-sized electrostatic cans! The first few times I heard the Periodic Be IEMs in action, I had visions that a "perfect" transducer was somehow directly linked to my eardrum. Wiggins wins this round!

Imaging with these IEMs is shockingly great. Dan argues that a single beryllium dynamic driver can beat a multi-armature design because it is much more impervious to resonance—which is demonstrable through measurement. I don't have $1000 multi-armature IEMs to compare, but the science behind the concept looks solid.

Before using the Periodic Be IEMs for music, I ran the acoustic personalization on my Samsung Galaxy S7 Edge , and the results were instructive. Unlike all other headphones I have tried, I heard just about every single test tone. Unlike all other headphones I have tried it with, the optimizer reported my hearing in both ears as excellent. This result is in agreement with the audiology exam I took last year, which similarly required identifying if a tone is playing. Long story short, these headphones are the most detailed-sounding that I have used, and that's evident when using the optimizer.

Now, while both my ears work great, a slight dip in bass sensitivity in my left ear... still above excellent... exactly coincides with the dip the audiologist found. That probably came from driving with the window down in my youth, back in the days when air conditioning was not always standard in used cars (late 1980s, early 1990s). I only mention that because with all other headphones, what the optimizer shows is gaps in the headphones performance while with the Periodic Be headphones the optimizer only corrects for the difference between my ears.

With the knowledge that my ears still work, I proceeded to use them to listen for the Be's real-world limits in terms of bass extension. Using a PC connected to a Denon AVR-X4300h receiver, I played sine wave test tones from Room EQ Wizard (REW) and confirmed that bass was clean right down to 12 Hz (where I could still sense the pressure, even though the tone is inaudible). And crucially, bass from 16 Hz on up was clean and distortion free. Plus, it was so tight and pure I had to double check that my subs were not running. Usually I can tell "headphone bass" apart from subwoofer bass, but these IEMs are so good they fool you into thinking you're feeling the deep notes.

All this performance-related excellence translates to multiple sublime listening experiences. At home with good amplification, the capabilities of the Periodic Be IEMs seems boundless (aside from turning them up too loud). But even when walking my dog, or while I'm on a flight, I find they can make music captivating to an extent I've never before experienced from $300 headphones, no matter what the design.


I've already had these headphones for months, so there's no point in listing individual tracks. I've listened to many dozens of albums and likely thousands of songs through the Periodic BE IEMs. Artists cover the gamut from Pink Floyd to Bassnectar to Dead Can Dance to Elvis to Biggie Smalls to Carl Orff to Beethoven. It would be silly to pin these headphones down as being "good for rap" or "good for jazz." These headphones are good for music. Period.

I use the Be IEMs all of the time, so if you have any questions, hit me up in the comments.