Listening to music on your phone is more than just streaming something from Spotify and putting on headphones—a lot of processing happens between your favorite media service, your device, and your ears. Qualcomm is one of the many companies that manages these steps, especially when it comes to Android phones that use its Snapdragon processors.
I recently visited Qualcomm’s San Diego headquarters and toured the audio lab, which develops and refines how Snapdragon-powered devices handle music and other audio content. There I also tried out some of the latest features that Qualcomm’s Snapdragon Sound audio platform will support on future phones.
Sound Rooms by Qualcomm
Qualcomm’s audio testing lab consists of multiple sections on multiple floors, all serving different purposes. The purest and most accurate sound measurements take place in three laboratory-built anechoic chambers.
Qualcomm’s acoustic anechoic chamber is designed to allow complete silence (Image credit: Will Greenwald)
Acoustic anechoic rooms are more than soundproof rooms; They are effectively anti-sound rooms. They are designed to allow total silence by not only completely blocking out all outside noise, but also preventing any kind of sound reflection in the room itself. The largest of the lab’s chambers, a nine-ton box that several people can stand in, is mounted on vibration-damping isolators and uses huge wedge-shaped sections of foam installed on most surfaces to absorb most sound frequencies down to about 160 Hz to absorb.
The lab has two additional, smaller chambers of a similar design, each just large enough to hold a Head and Torso Simulator (HATS), or human-torso-sized dummy with microphones that accurately simulate human hearing. Testing is performed in all three chambers using a HATS, reference microphones to measure speaker output, and reference speakers to measure microphone input.
To test and advance spatial audio technology, the lab must be able to pick up and analyze sound from multiple directions. To do this, Qualcomm built a test sphere. The geodesic sphere is large enough to fit one person and features 25 speakers pointing at the center from multiple directions. An engineer (or a HATS) can be placed in the center of the sphere to receive the multi-directional audio signals and measure performance.
This spatial audio sphere is big enough for someone to fit in and features 25 speakers pointing at the center from different directions (Credit: Will Greenwald)
Other real-world testing areas are set up around the lab, including three anechoic (but not anechoic) rooms to analyze how voice assistants process voices like smart speakers. There are also rooms arranged like offices and living rooms, including the one where Qualcomm demonstrated some of Snapdragon Sound’s advanced features.
The new tricks of Snapdragon Sound
Snapdragon Sound is Qualcomm’s audio platform, a collection of unifying technologies in phones, headphones, and other audio-related devices. Snapdragon Sound enables features like lossless audio over Bluetooth, head-tracking spatial audio, and Auracast broadcast audio between multiple transmitter sets. Mike Canevaro, Director of Snapdragon Sound at Qualcomm, demonstrated these three features to me.
Lossless audio over Bluetooth
Lossless audio over Bluetooth is exactly what it sounds like: the ability to listen to lossless audio files over Bluetooth. This is not easy to accomplish due to Bluetooth’s data bandwidth limitations, which is why virtually all Bluetooth devices use lossy audio codecs instead. Qualcomm’s AptX Lossless codec is one of the few exceptions to this rule: it can upscale audio signals to lossless quality when wireless conditions can handle it (e.g. when no other devices are nearby), and downscale the signal lossy quality in crowded wireless environments. AptX Lossless is an evolution of AptX Adaptive, an earlier AptX codec that can also adjust the quality of the signal on the fly.
This Head and Torso Simulator (HATS) is a human torso-sized dummy with microphones that accurately simulate human hearing (Image credit: Will Greenwald)
“Today, we remain the only company in the world that can actually offer a lossless solution over Bluetooth,” said Canevaro. “Using our AptX Adaptive encoding, we’re actually able to scale up to 1.2 megabits per second, allowing us to actually stream losslessly over the connection. Today we do [24-bit/96kHz] high-resolution audio, 16-bit/44.1 CD lossless and 16-bit/48 lossless.”
I heard some AptX Lossless audio over Bluetooth using Qualcomm development hardware. Audio clarity and detail can be as much a matter of gear as the signal sent to it, and even high-quality lossy audio can sound great with the right headphones. Still, the test tracks I listened to on Qualcomm’s headphones sounded incredibly detailed and subtle over Bluetooth – on par even with high-end wired headphones. My first impression is that AptX Lossless has a noticeable advantage in signal quality over both AAC and LDAC. Of course, like all codecs, AptX Lossless requires both your phone and headphones to support it.
Head tracking spatial audio
I also tried Snapdragon Sound’s head-tracking spatial audio feature. The platform supports sound sources from multiple directions, not only by mixing audio to simulate directional mapping, but also by using motion sensors in headphones to adjust these sources on the fly based on how you move your head.
The demo was a simple promotional video of the technology with audio spatial information encoded into it. The narrator in the video sounded like she was speaking right in front of me, and as I turned my head left and right, her voice panned between my ears to stay anchored relative to my position. It was an effective demo for horizontal positioning, although head tracking didn’t fare as well vertically; When I tilt my head up and down, the sound doesn’t adjust quite as realistically as when I turn it left and right.
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We’ve seen head-tracking spatial audio on the Apple AirPods Max and AirPods Pro, as well as certain gaming headsets like the Audeze Mobius, while this type of audio processing is common in virtual reality headsets. Snapdragon Sound is a promising way to bring this experience to Android devices via Bluetooth, although headphones with built-in motion sensors are required to work. And as with other head-tracking device-based spatial audio, Snapdragon Sound’s implementation works with a variety of standardized spatial audio content such as Dolby Atmos.
Auracast on Snapdragon Sound (Credit: Will Greenwald)
Auracast: Multipoint public audio
Finally, Auracast is one of the latest features introduced by the Bluetooth Special Interest Group (SIG), the standards organization that oversees Bluetooth. It allows Bluetooth headphones to wirelessly connect to and switch between multiple publicly broadcasting devices. With this feature, museum visitors can access virtual guides to various exhibits, or allow exercise enthusiasts to tune into one of the TVs at a gym simply by tapping their headphones. Auracast differs from headphones that simply support two simultaneous connections because it can’t be paired with just one (or two) devices; Instead, it quickly switches between a potentially unlimited number of public service devices. Auracast is still in its early stages, but Snapdragon Sound will support it.
I tried Auracast’s Snapdragon Sound implementation in Qualcomm’s test lab. Two phones were placed in front of me and each began broadcasting via Auracast. I plugged in my test headphones and was able to toggle between the two phones by double-tapping one of the earbuds. It worked almost flawlessly, although there was a half-second hiccup with each switch where I could only hear audio through the left earphone before both fully kicked in. Still, for a tech demo, this was highly functional.
The future of hearing
While all of these features fall under the Snapdragon Sound label, each has its own set of requirements between Snapdragon-powered phones and headphones in order to work. Whether you want Bluetooth lossless audio, motion-based spatial audio, or Auracast compatibility, the implementation of each and every feature on a specific headphone depends on the manufacturer.
Qualcomm makes the chipsets and unifying software elements that enable these features, but you won’t really experience them with your own ears until consumer devices start implementing them. It’s clear Qualcomm is doing a lot of work to make this possible, and we’ll likely see new products leveraging its work in the near future.
For more information on the technology shaping what you hear, check out our guides on Bluetooth codecs, equalizers and lossless audio.
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