Audio is commonly, and sometimes unknowingly, the missing piece a video needs to create an immersive and realistic experience. Subtle sounds in the background, well-mixed dialogue, and directional sound add to a story in ways you may not even notice until they aren’t there.

For the past few months, I’ve been using Sennheiser’s $300 Ambeo Smart Headset to record stereo binaural audio in my day-to-day life, and my smartphone videos and mobile audio recordings have never been this great. The headset — which is part binaural recorder, part headphones — was an exciting product to me because I work in the field of audio, and I love to record stereo soundscapes. I was also looking for a new pair of earphones.

When you’re out and about in the world, there’s a lot you don’t notice sonically because you tune it out in your head. But strip away all your visuals — just listen — and suddenly all these subtle, ambient noises begin to surround you. Someone 20 feet away is pulling tape off a roll; someone at the end of the block sneezed; and a dog’s collar jingles as it looks over at you while you’re holding a noisy plastic bag with your roast beef sandwich in it. These are the kinds of simple and surprising sounds you pick up when listening to the world recorded in binaural audio (or “3D” audio, as some marketing people have been calling it).

Binaural audio is the practice of recording stereo audio (left and right channels) in a way that mimics human hearing, which has traditionally come down to sculpting a human head and embedding the microphones in a model of a human ear. It’s a fairly simple concept that dates back to the early 20th century and was mostly popularized by the Neumann KU100 dummy head. But it hasn’t really been utilized in a lot of media.

It’s usually a hassle to casually record binaural audio, but I’ve been able to take this headset out of my pocket anywhere because of how portable it is. The Ambeo headset just looks like a pair of in-ear headphones, but it also has two omnidirectional microphones on each “ear.” It enables you to record a 360-degree soundscape of your surroundings — almost exactly the way you hear it if it were outside of your head — just by plugging right into an iPhone via the Lightning port. (The Lightning port has recently given me connection issues, which I’ll discuss later; an Android version is also in the works.) You can offload these stereo recordings to anywhere you’d like and listen exactly the way it was recorded.

Note: the best way to listen to binaural recordings is with headphones.

I have been really intrigued by the process of recording realistic stereo audio, and I try to incorporate it into my work and hobbies as much as I can. Whenever I travel, I bring along a 3Dio binaural microphone (along with a mobile audio recorder, XLR cables, extra batteries, a pair of sound-isolating headphones, etc.) to capture soundscapes of city streets, forests, or even public transportation that are specific to that area. Being able to record realistic stereo audio in a compact and on-the-go way was something I was actively looking for.

Notice the jingle of change on your left when I’m walking through the subway.

The audio quality on the Ambeo Smart Headset is surprisingly good. I’ve used binaural earphones before, and the audio quality has not been any better than a regular headset mic. These were clearly designed to grab realistic sounds so the audio is crisp and defined, and they have a reasonably low noise floor (the unwanted sounds from interference or buzzing in the audio signal that sacrifice the dynamic range of your recording). That’s good, considering you’re using two omnidirectional mics, and you’re never really in a place with no sound. Although it’s hard to distinguish audio quality when everything sounds like it’s outside your head, the definition and clarity are enough to fool you into thinking you’re listening to the real world.

Here’s a comparison between the Ambeo Smart Headset plugged into an iPhone 7 and a binaural microphone (3Dio Free Space Pro II) plugged into a professional audio recorder (Sound Devices Mix Pre 6). I was very surprised by the difference. Right out of the recorder, I ended up preferring the Ambeo recording. I won’t get too into it, but the 3Dio mic sounded like it had way too much high end when comparing the two. However, when I mimicked the Ambeo’s frequency response on the 3Dio audio, I ended up preferring the 3Dio.

Sennheiser has a dedicated recording app that enables you to record up to a 96kHz sample rate with 24-bit depth. You can also use other apps, like Apple’s voice memo, Clips, and even camera apps to add realistic binaural audio to videos that you take on your phone. I think this will be a standout feature when people start using these for concerts or parties. This way, they can listen to these videos years from now and be transported back to hearing glasses clink all around them or audience chatter and guitar rock 50 feet in front of them.

The drawback to using a mobile-first binaural headset is trying to share it. Posting your video on Instagram or Snapchat puts your audio in mono. Right now, sharing immersive content is not that easy. And if someone does listen to your binaural audio, the magic is gone if they play it through a smartphone or Bluetooth speakers.

These headphones do gain some additional listening features with the dual microphones though. One of those is noise cancelation, but I never really felt like it worked well enough to use. The best case was when I was on an airplane or drowning out the low rumble when waiting for a train. But did not work as well as the noise canceling you’d get from over-the-ear headphones.

Sitting down on the Metro-North train to New Haven. You can hear a few people talking behind me.

What has been useful is the headphones’ “transparent hearing” mode. Like some wireless earbuds, the Ambeo Smart Headset allows you to turn on the microphones to monitor outside noise without recording, as if you weren’t wearing them at all. So instead of putting them in my pocket when I’m talking to someone, I can quickly pause my music, turn on the transparent hearing, and switch back to my music when the interaction is done — all by using the controls that are integrated on the cable.

I recorded this on Christmas Eve as I was walking through snow in my hometown. A thing to note here is that you do need to worry about how windy it is outside.

Unfortunately, the headphones also stopped working on me after several months of testing, failing to connect to any iPhone’s Lightning port for more than a few minutes. This could be a combination of wear and getting them wet in the rain, but it’s making me hesitant to trust that they should be used as a default pair of commuting headphones. Sennheiser declined to comment on the issue, but attempted to troubleshoot the problem and offered to send a second review unit, which we declined.

This is something to think about when it comes to Lightning-powered headphones. How long are they supposed to last? When these break, how hard or expensive are they to fix? I’ve owned many analog earphones, and they have almost always fallen apart within a year — especially when I’m wrapping them up every day and putting them in my pocket. Attaching high-quality active microphones to thinly wired earphones that tangle may not be the most durable or dependable way to record audio, so you might end up sacrificing shelf life for portability.

As an audio engineer who likes to travel light, desires some noise cancellation, needs to pause audio frequently, and loves recording and archiving ambient soundscapes, the Sennheiser Ambeo Smart Headset is a great all-in-one gadget — at least while it worked. Who else would it be good for? I’m not exactly sure. Maybe “3D audio” will be that missing piece people will start looking for in vlogs. I haven’t been in too many situations where this was the best way to grab audio for my job, but knowing that I have something to record stereo audio with me whenever I go out is a good feeling.

Considering a Neumann KU100 dummy head is $8,000 (without any recording gear), $300 for a pair of binaural microphone / earphones you plug into an iPhone is great for that niche market of audio enthusiasts or YouTubers who are into ASMR. They don’t make sense for a lot of people, but it’s a step in the right direction for people to start thinking more about how they both record and consume audio.

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