There is no denying that more women are conquering the pop charts in the form of big names such as Beyoncé, Taylor Swift and Nicki Minaj. In the artistic realm, males and females seem to be on equal footing.

But there is still a significant gender imbalance in vital roles that go unseen, from executives to sound engineers who are lucky to appear in a liner note.

Mary Gaffney is one of the latter. She is part of an unintentionally exclusive group, the 5 percent, a minority of sound engineers who are women.

But before Gaffney, 64, could blaze a trail, she had to learn the craft. And that meant apprenticing herself to men. She was inspired by Hank Neuberger, former head engineer at Chicago Recording Co. "When everyone was saying, 'No, women don't do this,' Hank said, 'Give it a try,' " she said.

A softball game in the early 1970s got the ball rolling. Gaffney was playing on a team that also included Rich Warren, an engineer for a radio station. Gaffney was studying radio broadcasting at the time, and a few months later, Warren talked the radio station into hiring her.

She became a piece of "a very small framework of women creating entree for themselves," said Steve Albini, longtime recording engineer and owner of Electrical Audio in Chicago.

He said there has always been a general undercurrent of sexism in all traditionally male-dominated industries, especially technical occupations. An unfortunate result of this is lost talent.

"Any time you take half the people, cut half the potential participants out of a scenario, then you're half as likely to have your chance of finding the best person for the job or finding the unique insight," Albini said.

With few female role models to follow, Gaffney became one. Having once been "tutored," she said, by engineers who ran successful studios, Gaffney now runs one herself. She is the audio supervisor for Chicago Public Media.

She's a rarity in the profession. When told that women account for 5 percent of all audio engineers, according to SoundGirls.org, Neuberger (who supervises broadcast audio for the Grammy Awards, among other jobs) said he's not even sure it's that many.

With a music education degree from Duquesne University in Pennsylvania, Gaffney started out singing backup vocals. Enticed by the other side of the glass, she started experimenting with recording equipment.

When she found out that women weren't in the business, she said, "That surprised me, but didn't stop me."

Things are changing, but slowly. "Conventions and stereotypes and the reluctance of people to break them has just gradually been eroding over time," Albini said.

Neuberger said that he "really has no clue" as to why there are so few women in this field and that it remains a mystery to him.

"It's very much a bro society," said Juliana Armbrust, who has mixed bands at Pitchfork Music Festival for the past seven years.