At exactly 4 p.m., the CEO walks to the elevator, punches numbers on the keypad and waits for the doors to open to the third floor.

He steps off, glides to the center of the room where a dozen or so men and women sit waiting, whips out his Martin and Co. acoustic guitar, a 25th wedding anniversary gift from his wife, and begins singing: “He’s got the whole world in His hands / He’s got the whole wide world in His hands.”

No one can say for sure whether they recognize Harley Tabak, the CEO of Jewish Home Life Communities, or the lyrics to the songs he sings, no matter how familiar.

The men and women here suffer from dementia. They may or may not remember their own names, but none of that matters. Tabak isn’t looking for recognition or applause.

This is his way of connecting with residents and staff at the communities he manages.

“Singing helps me build bridges with people,” he says.

And so every Friday for nearly 40 years Tabak has been showing up.

To sing.

Although he’s never fancied himself a professional singer, Harley Tabak has been singing for nearly his entire life, beginning at age 7 in his temple choir and continuing, as a way to attract women, in high school and college.

Lucky for Tabak, it worked.

The night he met his wife, Terri, he sang “If I Were a Carpenter” for her. She was smitten. He was, too, and that very night he asked her to marry him. Terri said yes.

That was 40 Februarys ago and the 61-year-old grandfather still has his girl.

Soon after marrying in 1976, Tabak earned a bachelor’s degree in religious studies from Franklin and Marshall College in Lancaster, Pa. He then worked a couple of years in retail management before heading to George Washington University, where he earned a master’s in long-term health care administration.

He continued to sing in college and at nursing homes where he volunteered.

In 1983, he became a volunteer cantor at Congregation Ner Shalom in Woodbridge, Va., where he and his family had settled.

That gig lasted for some 20 years, even though he often says his niche audience is girls under 5 and women over 85 with some form of dementia.

“There’s a scene in ‘Animal House’ in which John Belushi takes the guitar from the man singing to women on the stairwell and smashes it,” Tabak says to make his point before heading to the third floor. “I’m the guy singing that music.”

Actually, Tabak is much better than that, but I can appreciate someone who doesn’t take himself too seriously.

Tabak doesn’t remember the precise moment he began singing at the senior care homes he manages. It simply became part of his schedule.

“I’ve done it everywhere I’ve worked in my career, and I especially like to sing to those who have profound dementia,” he says. “It’s a way of reaching them that other ways of communicating hasn’t proven to be as effective.”

After nearly three decades of working for hospitals and for-profit nursing homes and assisted-living communities, Tabak accepted the CEO position.

It was a chance to finally merge his management skills with his desire to minister to people.

“I didn’t think I could get into medical school and I didn’t think I had the temperament to be a rabbi,” he says. “What I do now is kind of a mixture of both of those.”

In the 12 years since arriving here in 2004, Tabak has seen the need for senior care increase. The number of services offered by Jewish Home Life Communities alone has more than tripled from two to eight and range from independent living, to rehabilitation and private home care, to assisted living, skilled nursing and hospice services.

Tabak makes it his business to visit each one and he always sings. The performances quickly earned him the “Singing CEO” title.

“Singing for 30 minutes is the easy part,” he says, “but if I can reach them, create a few smiles, then it’s quite rewarding.”

The Friday before Christmas he was at the Berman Commons Assisted Living & Memory Care in Dunwoody. As he sang a medley of American folk songs mixed with some Jewish melodies, residents clapped and swayed in their seats. Some sang along with him. A few, including Allan Cohen, danced through every tune.

“Tomba la liga” (tell me pretty one, tell if you know) was, no doubt, a favorite.

Research published early this month in the Journal of Alzheimer’s Disease revealed that musical activities enhance various cognitive skills, such as working memory, executive functions and orientation, especially in the early stages of dementia. People with long-term, chronic conditions who still manage to be positive about their lot in life have always held a special place in Tabak’s heart, but there’s a line in a popular Everly Brothers’s song that captures better than anything what those Friday singing engagements have meant to him all these years: “Just to see you smile makes my life worthwhile.”

And judging from the looks in their eyes, it makes the residents’ lives worthwhile, too.