Text Heikki Kivelä Photos Teppo HirviKunnas & The Producer

A more personalized version of the track.

While various room calibration technologies that tailor the sound are already standard features of even affordable audio devices, the phenomenon is not yet as common in the headphone sector. There is a reason for this, as Denon’s recent PerL Pro True Wireless proves to be one of them!

Basically, each of us hears sounds around us in slightly different ways. The reasons for this can be found not only in the functioning of the ear and the anatomical structure of the ear, but also in subjective habits. In the case of music, the individuality of hearing becomes even more pronounced, especially when earplugs are placed in the ear.

Of course, the playback could have been fine-tuned and modified long ago with various frequency correction devices, and many of them are also used to a greater or lesser extent when optimizing the playback profile of the headphones. Automatic measurements and the EQ profiles they form, on the other hand, are somewhat rarer. We came across a different view on this issue long time ago in the previous AVPlus issue 6/23 when testing JBL’s Tour One M2 headphones, where customization for the user’s ear was implemented by responding to various test sounds.

With the new JBL model in mind, we were interested to test Denon's new PerL Pro True Wireless earbuds with active noise cancellation and all the modern features in place. This is a high-priced full-wireless in-ear model in its product category, costing 349 euros. Its main selling point is the Masimo Adaptive Acoustic Technology (AAT) technology for hearing measurement and the PerL Pro earbuds' user-specific personalization using the measurement results.

Unlike JBL, for example, the Denon – or Masimo, or actually the Nura company, which the aforementioned recently acquired – implementation involves audio measurement and adjustment of the playback profile taking place completely automatically. However, the prerequisite is that the smart device must be loaded with the free Denon Headphones app and registered as a user. Upon launching the app, the user agrees to provide various data about themselves to the manufacturer in exchange for improved audio quality.

Basic things are in order

The Denon PerL Pro True Wireless is a fairly standard product in its product category, with the only deviation from its conventional design being the saucer-shaped design of the earphone housing's outer part. The button itself is lightweight, weighing 8 grams, and on its outer side there is a touch control surface and, as a visual detail, a neat small Denon logo. The graphite gray finish is mostly practical.

Denon PerL Pro True Wireless headphones 1 — The Denon PerL Pro differs from traditional mouse designs with its board-like design. The buttons are lightweight and clean, and they stay firmly in place.

The fit of the earhook on the ear has been improved with textured inserts, with two different models available in the package: a winged and a non-winged model. The likelihood of a snug fit in the ear canal is increased by the convenient five pairs of different earplugs: four silicone ones from small to large, and one plush memory foam model that fits snugly in the ear like a second skin. The downside of the memory foam is that it wears out faster, so they may need to be replaced after more intensive use.

The headphone case, on the other hand, weighs 55.5 grams and measures 73 x 29 x 35 millimeters, so it’s not particularly large but not small either. In the pocket of my running shorts it does take up quite a bit of space, but with slightly looser pants it doesn’t really do that much.

For example, when leaving for a run, you can, if you wish, leave the case at home; and that’s worth doing, because the case hasn’t been labeled with an IP rating. As for the headphones themselves, the rating is IPx4, which practically means that they can withstand water splashes from all directions. Therefore, a jog in the rain won’t be a problem if you don’t get completely soaked.

Despite their boat-shaped design – or perhaps precisely because of it – the PerL Pro headphones fit exceptionally well, although you do need to get a little used to their layout at first.

Denon PerL Pro True Wireless headphones 2 — The Denon PerL Pro comes with a short USB-to-USB-C charging cable, two fit-lock clips, and five adapter pairs. The equipment is well-rounded, and the inclusion of memory foam adapters in the package is always a plus.

Implementation and use

The Denon PerL Pro headphones are a typical product in their category. Their pairing with the Apple iPhone 13 Mini went smoothly on the first try, from setting up the Bluetooth connection to installing the Denon Headphones app.

The installation and use of the control app is so important that the PerL Pro headphones’ clear treble feature is a user-customizable equalizer profile using the Masimo Adaptive Acoustic Technology method. This feature can only be activated with the guidance of the app.

In practice, the user must place the headphones tightly and securely in their ears and remain in that position for about a minute, during which time the app performs measurements using various test sounds. The user does not need to participate in the measurement in any way.

In addition to the customized repeat profile, the user can also adjust the playback with a 5-band equalizer and the ”immersion mode” slider, which seems to be a kind of bass tone controller. Furthermore, if desired, the playback can be enhanced by turning on the mode mode, which, with certain types of material, slightly amplifies the sound focused on the head of the headphones.

The noise cancellation mode is on by default in PerL Pro headphones, as is the case with many other current noise-canceling headphones models. The microphone phase can also be flipped, which activates the social mode in the headphones, which discreetly lets the ambient sounds through. This way, for example, a conversation in a shopping mall cashier can take place without having to take the headphones out of your ears.

Otherwise, there’s not really anything to mention about the PerL Pron. The playback stops when you take the headphones off, the English audio responses are glitch-free, and all the controls work with a steady level of reliability.

Denon PerL Pro True Wireless headphones 3 — Denon uses the Masimo Adaptive Acoustic Technology in the PerL Pro headphones, which is based on otoacoustic emissions, or the sounds produced by the inner ear in response to stimuli. The method works, but the end result may not be better than the default settings. Therefore, the Denon Headphones control app also includes an immersive equalizer to adjust bass and a 5-band equalizer.

The continuous playback time of the headphones with moderate listening volume is approximately eight hours, and with the additional charges provided by the storage case, the total usage time increases to 32 hours. This is a mid-range result in modern times, even slightly below the average in its price range.

The battery in the case charges to full in about an hour, and the headphones reach 100 percent capacity from zero after about two hours in the case. Five-minute quick charging gives an additional hour of playback time. Charging is done via the USB-C connector, and Qi wireless charging is also supported.

More individual sound

We tested PerL Pron AAT hearing measurement with two test subjects. The younger of them was surprised at how the center frequency and darkness of the sound after the measurement became more even, while the older of them thought their own profile was better than the default setting. After cleaning the settings, we also compared the different profiles and discussed the reasons for them. When measuring, the app is informed of the user’s age and gender, which in turn will affect the result.

In both cases, regardless of the trumpet material, the AAT measurement attenuated the extremes of the sound, which is surprising given that human hearing should actually lose sensitivity in the higher frequency range with age. For some reason, the AAT measurement did not take this into account, but instead further attenuated the rather moderate treble sound.
As for the muffled bass, the problem wasn’t too big, as its level can be adjusted quickly with the immersion slider. In principle, the mid-range and treble can also be played quite well in a personalized mode by changing the EQ settings, but we think this kind of violates the idea of tailoring the automatic AAT measurement and playback.

On the other hand, it’s also good to see that by switching between the default mode and the personalized mode, you can see what happened during playback after calibration, and from that you can try to fine-tune the playback to achieve a more preferred final result. At the same time, you’ll also learn something about the operation of the equalizer, and possibly also about your own musical preferences.

However, it is assumed that the manufacturer did not necessarily strive for this measurement technology and its functionality.

One way or another, with the smaller or slightly larger adjustment, the PerL Pro headphones produced quite a bit of sound that was functional, but the AAT measurement itself didn’t bring about a major revolution in the usual way. In any case, when it comes to in-ear headphones that are placed inside the ear canal, the user must first ensure that they are securely in place. After that, using the app’s frequency correction and immersion settings, the playback can be adjusted exactly as desired, because with the factory settings the sound can initially appear slightly flat and thin.

But you get good results from it, although more with traditional methods than with the latest ones!

Traditional functionality

The Denon PerL Pro headphones are smart and stylish in their category; they are reliable, well-sounding, and smoothly functioning headphones that have everything in place – although their price is quite high compared to the overall package. The enhanced playback personalization, which is touted as a top feature, also doesn’t really work beyond the idea level; it doesn’t actually improve the playback significantly compared to the default settings. However, this doesn’t mean that the AAT method won’t work, because even among the test participants, there were strong positive and negative feelings about its impact on the playback. However, with the PerL Pro being adjusted manually, it sounds quite well, so you don’t have to compromise on the sound quality!

Denon PerL Pro
Price	149 euros
Representative	Simex
Additional information	Denon.fi
Operating principle	Reverse microphone earphone
Bluetooth version	5.3
Supported codes	AptX Lossless, aptX Adaptive, aptX Classic, AAC, SBC
Multipoint connection	Yes
Element	10 mm
IP protection	IPX4
Battery life	24 + 8 hours
Download time	Case 1 hour, headphones 2 hours
Quick charging	5 minutes -> 1 hour
Wireless charging	Qi
Charging port	USB-C
Cornices	XS, S, M, L, foam
Other	Two wing options
Weight of the headphones	8 g
Dimensions of the case	73 x 29 x 35 mm
Weight of the case	55.5 g