Thunderspace app uses binaural audio to create 3D space for your ears

By Carmel DeAmicis , written on July 9, 2013

From The News Desk

The sound of a train speeding towards me made my heart flutter. In an instant, all my concentration went to my chest. The world shrunk small, and the train train whipped past, leaving an echo in its wake. As birds started cawing in the background, I opened my eyes and the chatty Castro cafe reappeared.

Up until that point, I wasn’t feeling too impressed with the new Thunderspace app, which I had just downloaded to my iPhone. The designer of the popular Waze weather app worked with seasoned sound recordist Gordon Hempton to create what they’re calling a 3D auditory experience. The app supposedly mimics the way our ears hear in real life, by timing it to reach one ear before the other. To create it, they used special microphones with ears -- literally, fake anatomically correct ears (see pic) -- to record a thunderstorm through the two channels that then map to your left and right ear. Using a simple pair of earbuds, anyone willing to pay $2.99 could treat themselves to a relaxing thunderstorm experience (like a sleep machine, except better).

Thunderspace claims that it isn't about a simple sound recording of a's how that thunderstorm is delivered to your ears, creating a 3D "surround sound" effect that mimics reality in a way normal stereo tracks can't. As the skeptic, I wondered how realistic a thunderstorm could possibly sound when coming out of my tiny earbuds. Doesn’t Pandora have a thunderstorm channel at this point that would do the same thing?"

Initially my suspicions were confirmed. I didn’t immediately test the thunderstorm track -- I eased myself in with one of the demo tracks in the app “introduction.” Seagulls cawed, waves crashed, and I was more impressed with the speaker range of the bar playing Lady Gaga next door than the 3D auditory experience I was supposedly having. But then…the train arrived.

I could hear it coming from hundreds of feet away, and its insistent existence made me feel like I was standing on a train track in the Midwest, surrounded by cactuses and dirt. I’m not entirely sure what to compare the experience to, aside from perhaps Disneyland’s haunted mansion ride, when voices and sounds swirl around you. The app seems to do best with “moving” sounds, i.e. audio that naturally approaches you and fades away as though you were moving through space. The effect places the listener directly inside the auditory world, such that that world feels more real and present than the immediate physical surroundings. However, sounds that would hit a listener’s left and right ear simultaneously -- like waves -- basically sound the same as they would on a regular soundtrack.

Like many bursts of creativity, a late night Wikipedia session led to the creation of Thunderspace. Franz Bruckhoff, who is running the one-man Taptanium app workshop out of his studio in Germany, was researching audio mixing and came across the term “binaural audio.” He discovered that when microphones were placed in fake mannequin ears, they picked up the audio cues distorted by the "head shadow" and the shape of the ears. As a result, an amateur could jury-rig a 3D sound recording with limited resources.

Bruckhoff got so excited he decided to make his own 3D mix tape. He ordered anatomical ears like the ones used in medicine (from Amazon, where else?) and scotch taped them onto a plastic cylinder. He then replaced speaker ear bugs with little microphones, stuck then in his mannequin’s ears, and waited for a thunderstorm. He didn’t have to wait too long before one arrived, and he placed his mannequin in an enclave on his roof and hit record. The end result -- “Roof Garden” -- was so pleasant he decided to test it out at a party. Bruckhoff turned the lights off in a room, and people lined up to listen to the track through headphones and experience a "thunderstorm." When the queue started stretching out the door, he decided he might have a hit on his hands and ought to make the app.

He hired Emmy award-winning sound recorder Hempton, who uses the high quality, professional mannequin heads to record 3D audio in nature for everything from movies to art installations (the real mannequins -- Neumann KU-100′s -- cost $8,000). Bruckhoff developed the iOS app, a pretty, visual experience in its own right, to house eight different tracks. Users get Bruckhoff’s original “Roof Garden” track and Hempton’s “Waterscape” with the app purchase, and then they can pay $1.99 (discounted to $1.00 for now) for seven of Hempton’s other recordings ranging from “Desert” to “Rainforest.” My personal favorite is “Moonlit.”

Bruckhoff is not the first app developer to push 3D sound. Naturespace (note the name similarity…) offers a handful of free “holographic” audio tracks like Daybreak Songbirds and Riverwind Dreaming. The company’s corresponding storm app -- Thundergod -- hypothetically also offers a 3D listening experience, although the app description and website don’t make it clear whether that’s the case. If so, Naturespace’s Thundergod is Thunderspace’s direct competitor, but Thundergod costs $10.00 and Thunderspace costs $3.00 (discounted $1.00 for now to "celebrate" the launch).

Bruckhoff understands the importance of marketing for app success, and he reinvested the money he earned from the Haze weather app (released in early 2013 to great success) to create a mini commercial bringing the Thunderspace experience to life. He spent $11,500 on the 24-person Hollywood production, and says he’ll be in the hole for it unless the app does well.

I fell asleep to the Thunderspace track pitter pattering that night. Knowing the technology behind it, I could pick out the differential of raindrops falling in my left ear versus right ear. The thunder itself was lovely -- it would boom slowly across the "sky," and the 3D sound gave it the space it needed to do so. I was so relaxed I barely heard the death rattle of the J train that enjoys waking me at 2 am.