Waves NX Headtracker

Impressive headphones for surround sound long seemed an impossibility. However, this has undergone a relatively unnoticed change in recent years: Almost every playback device is now capable of reproducing 3D sound (including common surround standards). The answer to the problem was therefore not special headphones or a new surround format, but the combination of long-established acoustic concepts with sensor technology to evaluate head movements and the computing power of our laptops and smartphones.

Position transmission via transmitter

We locate sound sources not only through the parameters that we mentioned at the beginning of this article but also unconsciously through minimal turns of the head. This is where the so-called Headtracker comes into play, and it has been on offer since 2016 as the Waves NX Headtracker; it’s a Bluetooth 4.0 transmitter attached to the headphones that communicates with the built-in NX software on your computer or smartphone. This automatically adjusts the sound output relative to head movement. The Headtracker should be attached as centrally as possible on the headphone bracket; rubber bands in several lengths are included for this purpose. One AAA battery supplies the Bluetooth 4.0 transmitter with power. The only button on the Headtracker serves both as an on/off switch and for pairing with the playback device. Despite the featherweight plastic housing without battery, the workmanship is appealing: The only thing that needs to be checked in advance is the attachment to the headphone bracket; if the rubber band is too tight, it could leave permanent dents in the leather of luxury models. Alternatively, it can be attached to a cap or hat, but this is not necessarily acoustically advantageous.

Binaural result

The software component of Waves NX comes in several versions, which are rather confusingly named. For smartphones, there is the free app Waves NX; for a computer, in addition to the Headtracker, there is a charge of about 10 euros for the software, which is also called Waves NX and described here. This includes a binaural decoder, which hooks into the signal path of your smartphone or computer as a virtual audio driver and combines the camera with Headtracking. The result can most easily be described as a VR setting without VR glasses. The sound reacts without noticeable delay to head movements in all three dimensions. In addition to spatialised stereo, 5.1 and 7.1 surround formats can be reproduced using Waves NX with standard headphones. Depending on the source, NX automatically selects a suitable speaker configuration. On PCs and Macs, a webcam can be used instead of or in addition to the Bluetooth tracker to determine the head position, but unfortunately, the quality of this CPU-intensive variant varies greatly depending on the lighting and its quality. The app itself shows the current head position in relation to the speakers being simulated. It is possible to define the “sweet spot”, i.e. the normal listening position in which the stereo source sounds directly from the front. An animated dummy head shows the position of the user’s head in relation to the virtual loudspeakers. The pre-sets “Multimedia”, “Voice” and “Movie Theater” offer different sized rooms and speaker distances. But if you want more precise control over your virtual listening room, you are in luck: for professionals, Waves offers two plug-ins with NX in the name: the NX Virtual Mix Room (US$109) and NX Ocean Way Nashville (US$199). Regardless of other features (support for ambisonics, detailed control over room size, reverberation times, etc.), these have a function that is sadly missing from the “normal” Waves NX: improved precision of 3D sound through EQ curves for a range of popular studio headphones.

How does it sound?

The precision of the three-dimensional effect with binaural stereo has mainly to do with the individual ear and head shape, but naturally, it also depends on which headphones are used. We need to pay attention to this point because the difference between “good” and “bad” binaural sound is extreme, not least due to the individual shape of our ears. One professional approach is to create your own profiles using online service providers or hearing aid acousticians. There are also a myriad of HRTF (Head-Related Transfer Function) files available on the internet that serve as blueprints for different ear and head shapes. Unfortunately, finding the “right” HRTF is somewhat tedious and makes for a rather obscure pursuit for the layperson. Fortunately, Waves avoids this stumbling block and allows the creation of a simplified HRTF model. For this, NX requires two values for your own head shape, which you definitely need to measure and enter before doing the first test. The difference between incorrect and correct values is absolutely crucial for a good listening experience. Conveniently, separate profiles can be created for several users. Once this step is completed, nothing stands in the way of the three-dimensional sound experience.

Improvement needed – the app

Unfortunately, Waves is rather neglectful with their smartphone app. Music can only be played via apps linked to the NX. On my iOS device, these were Apple Music, Soundcloud and Spotify Premium. Podcasts, Tidal or Netflix? You’re out of luck as they’re not recognised. The app was last updated several years ago; consequently, it would not even connect to my Soundcloud account, and my Apple Music library could only be partially searched. Instead of three room pre-sets, only the intensity of the reverberation in the virtual room can be adjusted in the app, and unfortunately, this setting is missing in the version for Mac and PC. And the fact that the graphic interface has not been adapted to the format of current smartphones seems almost trivial given the app’s other shortcomings.