Jack Mann was always an avid concertgoer. He found soaking up the local music scene in his hometown of Minneapolis, Minnesota a good way to unwind after a hard week at his sales and marketing job. But after a gig left him with a ruptured eardrum, he discovered the music industry was missing a beat and his pastime quickly turned into a full-time career. "Doctors told me to wear foam earplugs to my next concert," Mann told CNBC Make It. "But after putting them in, I instantly realized they destroyed the sound quality and are not designed for music." He questioned why there was no better alternative. Though injuries like Mann's are rare, around 440 million people worldwide are at risk of hearing damage due to live entertainment, according to an estimate from the World Health Organization. So he came up with Vibes, whose line of reusable "hi-fidelity" earplugs lowers high and low frequency sound levels equally, resulting in a more balanced sound than that from traditional earplugs.

According to Mann, that's a big solution to a problem most people don't even know they have. "It's a really big deal and people aren't very aware of it because it's a gradual decline," said Mann. "You don't wake up deaf one day. It's kind of a chip off a block of ice every time." "Every time your ears ring, that's irreversible hearing damage," he continued. "That ringing that you're hearing in your ears is those cells dying. There's no way to get that back unless someone invents technology to do otherwise."

Vibes Hi-Fidelity Earplugs Vibes

As it turned out, someone was listening. Shortly after launching Vibes in late 2016, Mann received an email from Shark Tank's production team who wanted to hear more. "Being in business only a few months, I literally thought it was spam," recalled Mann. Nonetheless, he called them straight away. The producers had seen his earplugs on a music/lifestyle blog and wanted him to apply for the show. The process was "rigorous," Mann said. Indeed, statistically it's harder to get on "Shark Tank" than it is to get into Harvard University. Of the 45,000 people who apply each year, less than one percent get to pitch to the sharks, while Harvard's acceptance rate this year was 4.6 percent. But it paid off. Within weeks, Mann was pitching on a national stage to a panel of celebrity investors — an experience he described as "intense" and "incredible."

Kevin O'Leary Scott Mlyn | CNBC

His 10-minute pitch won the approval of shark Kevin O'Leary, who made him an offer of $100,000 for a 35 percent stake plus $2 for every pair of earplugs sold. For Mann, however, that deal was too costly for his young business. "We were only in business for three months by the time we filmed, so it was very early to be giving up that much equity," said Mann, now 29, who is Vibes' sole founder. "Additionally, we weren't fully confident on our price-point at that stage. It was unclear what [impact] $2 royalties would have had." Mann walked away from the show empty handed, but he said has "no regrets." By taking the bootstrapping approach and working out of his van, his business has grown from an initial investment of $33,000 to $2 million in sales as of 2017. The show also provided him with necessary feedback and opened his business up to a whole new audience beyond concertgoers, he said. From employees at Starbucks coffee roasting plants and U.S. military skydivers to car racing fans and children with autism, the Vibes customer base has grown.

Model plays the guitar while wearing Vibes Hi-Fidelity Earplugs Vibes