A raft of voice-based hardware devices have emerged, aimed at companionship, productivity, or personal growth. These include card-shaped devices from Plaud and Pocket; pendants from Friend, Limitless, and Taya; and a wristband from Bee, which is now part of Amazon.
Now, two former Meta employees who worked on interface design have launched Sandbar, a startup that has created a ring called Stream for similar purposes. The company calls the ring “a mouse for voice” because it can take notes, help you interact with an AI assistant, and also let you control music.
Sandbar’s CEO, Mina Fahmi, has an extensive background in designing human-computer interfaces. He worked at Bryan Johnson’s Kernel and later at smart glasses startup Magic Leap. Kirak Hong, Sandbar’s CTO, worked at Google before joining CTRL-Labs, where the duo met. Meta acquired the startup in 2019, and its work eventually led to neural interfaces for the tech giant’s smart wearables.
Fahmi said that when large language models started emerging a few years ago, he built an experimental journaling app. However, he found that the app itself became a barrier to capturing his thoughts. Given his experience building hardware interfaces, he began exploring a conversational hardware interface instead.
“A lot of my ideas bubble up when I’m walking or when I’m commuting, and I don’t want to pull out my phone to interrupt that moment. I don’t want to shout into my earbuds where the world can hear me to talk through an idea. Kirak and I were trying to understand what it would take to actually capture a thought the moment it bubbles up. That’s how we came up with Stream,” Fahmi told TechCrunch in an interview.

The ring, designed to be worn on your dominant hand’s index finger, has microphones and a touch pad.
In a virtual demo, Fahmi wore the Stream ring on his index finger and recorded his thoughts by pressing and holding the touchpad. By default, the microphone is off, activating only with this gesture. The microphone proved sensitive enough to pick up whispers and transcribe them in the companion iOS app. Other apps like Wispr Flow and Willow similarly allow people to capture their thoughts quietly.
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Stream’s app includes an AI chatbot that converses with you as you record your thoughts. You can organize these into separate notes that either you or the AI can edit. The app also lets you pinch to zoom out and review what you have discussed over days or weeks. Sandbar has added a personalization layer so the assistant’s voice sounds somewhat similar to the user’s.
Fahmi said that in crowded spaces, users can wear headphones to converse privately with the assistant. Without headphones, the ring provides haptic feedback when it successfully registers a note, allowing you to add to-dos, take notes, or check items off a grocery list quietly.
Beyond voice functions, the ring’s flat surface doubles as a media controller, allowing you to play, pause, skip tracks and adjust volume. While many headphones offer similar controls, the ring could prove useful when your hands are occupied or you’re in transit.
The company is opening up pre-orders for Stream on Wednesday at $249 for the silver version and $299 for gold. Sandbar aims to begin shipping next summer. A Pro subscription tier — free for three months for those who preorder, then $10 per month — offers unlimited chats, notes, and early access to new features.
Fahmi said the company gives users full control over their data at any tier, with encryption both at rest and in transit. He added that Sandbar doesn’t believe in walled gardens and plans to support data exports to apps like Notion.
Sandbar has raised $13 million in funding from True Ventures, Upfront Ventures, and Betaworks.
Toni Schneider, a partner at True Ventures, said he had been skeptical of AI devices, as demos he’d seen before Stream weren’t impressive.
“I think a lot of people would agree that voice and AI go really well together. And [they also agree] that having a phone or even a laptop to interact with AI is kind of a lot when all you need is voice. So there should be some kind of new form factor out there. We looked at a lot of them, and a lot of them just didn’t quite hit the target. When Mina came in and showed us the demo, it made sense to us,” he told TechCrunch.
Competition is fierce in the voice-AI hardware space, with many builders exploring rings as a form factor. Fahmi said he doesn’t want Stream to be an assistant or a companion, but rather an interface for users to express their ideas while maintaining full control.
AI hardware has yet to achieve mainstream success. Humane sold to HP, Rabbit is attempting to improve user experience and engagement through software updates, and Friend is trying to leverage user backlash to fuel growth. Sandbar will need to prove that its ring form factor offers genuine convenience and value that pendants, pins, or wristbands cannot.
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![Scientists Say Some Black Holes Are Born From Other Black Holes
Since LIGO’s Nobel-winning discovery of gravitational waves—ripples in spacetime—the U.S.-based detector has been picking up on hundreds of signals from black hole mergers. And, after a decade of studying gravitational waves, researchers believe a significant fraction of black holes may come from cosmic chain reactions. A recent paper published in Physical Review Letters describes an analysis of 155 pairs of binary black holes, identified by LIGO and its sisters, Virgo and KAGRA, in Italy and Japan, respectively. According to the study, about 14% of merging black holes may be what’s called “second-generation black holes,” or black holes that form from previous mergers of two smaller black holes. This “hierarchical” backstory is vastly different from the textbook version of how black holes emerge from the explosive death of a star. “Overall in the universe, black holes are merging all the time,” Cailin Plunkett, the study’s first author and a graduate student at the Massachusetts Institute of Technology, told MIT News. “Now we’re seeing a relatively consistent picture where there’s a decent percentage of black holes that are coming from this repeated pathway.”
Tracking the invisible Gravitational waves that reach Earth’s detectors typically come from extremely intense events. Over the years, LIGO has picked up some truly perplexing signals. For example, last summer it found the most colossal black hole merger ever—and if that wasn’t wild enough, the black holes that took part in the merger lie within a cosmic “dead zone” for black holes.
This zone refers to a range of black hole masses in which, physically speaking, black holes can’t form through ordinary stellar collapse. From these discoveries, astronomers realized just how little we knew about black holes, which are challenging to investigate directly. In that sense, it was a no-brainer that the ever-growing catalog of LIGO’s gravitational signals would turn up entirely new insights about black holes. “It is increasingly clear, both from individual events and population analyses, that massive black holes exist in [this] range,” the researchers wrote in the latest paper. “These observations have spurred further investigation into mechanisms that can populate this gap.”
A wobbly imprint The latest research represents one such investigation. During mergers, the two black holes spiral toward each other along an orbital plane. When one or both black hole spins are misaligned, the orbital plane can wobble, or “precess,” the researchers explained to MIT News. The degree to which the disk wobbles acts as a parameter from which researchers can measure the masses and spins of the merging black holes. One telling sign of hierarchical mergers is that they’re “lopsided,” meaning one of the pair has a much higher spin and mass than the other. For the study, the team created an analytic model to capture the kind of wobble that would have emerged from second-generation black holes. Around 14% of merging black holes followed this pattern, and the second-generation black holes identified had a very specific range of masses, at around 20 solar masses or 40 solar masses and above. Of mysterious origins To be fair, that might not sound like a whole lot. But it demonstrates that a sizeable portion of known black holes indeed follow this pattern. As for why, the team suspects hierarchical mergers emerge from dense stellar environments. Simply, when multiple neighboring stars die and collapse into black holes, the dense environment can make it easier for those black holes to find each other and merge. That could further lead to the formation of second-generation black holes. Theoretically, this could “repeat potentially ad infinitum, by virtue of the fact that you have a ton of stars and black holes in this really dense environment,” Plunkett said.
But an ensuing mystery concerns those black holes in the 40-and-above regime, which coincides with the aforementioned “death zones” for black hole masses. According to stellar evolution theory, black holes born of supernovas shouldn’t leave any black holes above roughly 45 solar masses, explained Plunkett. “Yet we have seen black holes that are that massive,” she mused. “And the question is: Where did they come from?” For now, it’s hard to say when we’ll get an answer to that question, if ever. But one thing seems to be clear: black holes are a lot weirder than we could ever imagine. #Scientists #Black #Holes #Born #Black #HolesBlack holes,Gravitational wave,LIGO Scientists Say Some Black Holes Are Born From Other Black Holes
Since LIGO’s Nobel-winning discovery of gravitational waves—ripples in spacetime—the U.S.-based detector has been picking up on hundreds of signals from black hole mergers. And, after a decade of studying gravitational waves, researchers believe a significant fraction of black holes may come from cosmic chain reactions. A recent paper published in Physical Review Letters describes an analysis of 155 pairs of binary black holes, identified by LIGO and its sisters, Virgo and KAGRA, in Italy and Japan, respectively. According to the study, about 14% of merging black holes may be what’s called “second-generation black holes,” or black holes that form from previous mergers of two smaller black holes. This “hierarchical” backstory is vastly different from the textbook version of how black holes emerge from the explosive death of a star. “Overall in the universe, black holes are merging all the time,” Cailin Plunkett, the study’s first author and a graduate student at the Massachusetts Institute of Technology, told MIT News. “Now we’re seeing a relatively consistent picture where there’s a decent percentage of black holes that are coming from this repeated pathway.”
Tracking the invisible Gravitational waves that reach Earth’s detectors typically come from extremely intense events. Over the years, LIGO has picked up some truly perplexing signals. For example, last summer it found the most colossal black hole merger ever—and if that wasn’t wild enough, the black holes that took part in the merger lie within a cosmic “dead zone” for black holes.
This zone refers to a range of black hole masses in which, physically speaking, black holes can’t form through ordinary stellar collapse. From these discoveries, astronomers realized just how little we knew about black holes, which are challenging to investigate directly. In that sense, it was a no-brainer that the ever-growing catalog of LIGO’s gravitational signals would turn up entirely new insights about black holes. “It is increasingly clear, both from individual events and population analyses, that massive black holes exist in [this] range,” the researchers wrote in the latest paper. “These observations have spurred further investigation into mechanisms that can populate this gap.”
A wobbly imprint The latest research represents one such investigation. During mergers, the two black holes spiral toward each other along an orbital plane. When one or both black hole spins are misaligned, the orbital plane can wobble, or “precess,” the researchers explained to MIT News. The degree to which the disk wobbles acts as a parameter from which researchers can measure the masses and spins of the merging black holes. One telling sign of hierarchical mergers is that they’re “lopsided,” meaning one of the pair has a much higher spin and mass than the other. For the study, the team created an analytic model to capture the kind of wobble that would have emerged from second-generation black holes. Around 14% of merging black holes followed this pattern, and the second-generation black holes identified had a very specific range of masses, at around 20 solar masses or 40 solar masses and above. Of mysterious origins To be fair, that might not sound like a whole lot. But it demonstrates that a sizeable portion of known black holes indeed follow this pattern. As for why, the team suspects hierarchical mergers emerge from dense stellar environments. Simply, when multiple neighboring stars die and collapse into black holes, the dense environment can make it easier for those black holes to find each other and merge. That could further lead to the formation of second-generation black holes. Theoretically, this could “repeat potentially ad infinitum, by virtue of the fact that you have a ton of stars and black holes in this really dense environment,” Plunkett said.
But an ensuing mystery concerns those black holes in the 40-and-above regime, which coincides with the aforementioned “death zones” for black hole masses. According to stellar evolution theory, black holes born of supernovas shouldn’t leave any black holes above roughly 45 solar masses, explained Plunkett. “Yet we have seen black holes that are that massive,” she mused. “And the question is: Where did they come from?” For now, it’s hard to say when we’ll get an answer to that question, if ever. But one thing seems to be clear: black holes are a lot weirder than we could ever imagine. #Scientists #Black #Holes #Born #Black #HolesBlack holes,Gravitational wave,LIGO](https://gizmodo.com/app/uploads/2026/07/black-hole-hierarchial-mergers-1280x853.jpg)
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