Certain jobs need their employees to have an engaging, trustworthy voice. Think of the hospitality and retail industries. Since studies and focus groups have previously dissected the voice and categorized the key emotions of the person speaking over the years, Jobaline.com — a mobile-first job recruiter — has created an algorithm to better help hiring companies find the right fit.

NPR reported Jobaline has taken existing research and fed it into algorithms that determine how a job applicant’s voice makes others feel. How the speaker feels personally is irrelevant, Luis Salazar, CEO of Jobaline, told the news site; employers want to know how new hires will fare with their guests. Salazar references Al Pacino as an example of how tone can be emotionally engaging.

NPR played three samples of Pacino’s voice — each from different movies throughout his career — and despite his voice’s range, each sample has a “biological, inescapable fact” of emotion. Salazar said it doesn’t matter if he’s screaming or not; the average American loves his voice.

So far, Jobaline’s algorithms can pinpoint if an applicant’s tone of voice is engaging, calming, or trustworthy. Big companies are paying them to find the right workers for their hourly jobs. And so far, they’ve processed over half a million requests for hotel receptionists and call center staff. In these instances, an engaging and calming tone is important since, according to Salazar, the average span of attention is four seconds.

NPR added the beauty of Jobaline’s algorithm is that employers no longer have to wear themselves down with the job hiring process; by the time they get to applicant 25, they might discriminate against certain aspects, such as voice. An algorithm has stamina and isn’t aware of an applicant’s age, race, gender, or sexual orientation.

“Math is blind,” Salazar said. “That’s the beauty of math.”

People are becoming increasingly perceptive of the way other people sound. A person in a power pose, for one, sounds more forceful, punctuated, and strong. On the other hand, women with a creaky, low pitched voice (not unlike pop singer Britney Spears) are perceived as untrustworthy, incompetent, and less hirable.

Additionally, women find men with lower voices more attractive despite thinking these men are more likely to cheat on them. Psychology Today added “a strong, attractive voice has a big advantage of a person with a weak, unattractive voice.” Better yet, it’s possible for someone to improve the sound of their voice.

“For all of us, our best, strongest, most attractive and most natural voice comes from the diaphragm,” Preston Ni, author of How to Communicate Effectively and Handle Difficult People, wrote for Psychology Today. “A person who uses the diaphragm voice commands attention, ‘sounds’ more attractive socially, and is more likely to be perceived as a promotable leader. The diaphragm voice is the best sounding voice for both women and men.”

Practicing diaphragmatic breathing helps people use their diaphragm correctly. Ni said it’s as easy as inhaling and letting your belly rise, and exhaling and letting your belly fall. Singing and acting classes can also be helpful, since each class typically starts by warming vocals up from the diaphragm. Voice coaches, too, are an option for people who suspect their tone of voice holds them back in an area of their life, including but not limited to their career.