Like gnats, wind gusts and plodding players, cellphones can be surpassingly irritating on the golf course.
"You'll be into your swing, and the phone will ring," said Butch Baldwin, a retired longshoremen, as he paused between holes at Clifton Park Golf Course in Baltimore recently. "I think they should be put on vibrate."
But golf's relationship with smartphones is complicated, as modern convenience clashes with the sport's traditions.
For centuries, golf has been a sanctuary, a bucolic — if occasionally maddening — escape from everyday worries. Quiet was expected on the links so concentration on swings and putts wasn't interrupted. But with interest in golf stagnating, the managers of local courses and major tournaments — including this week's U.S. Open — are increasingly willing to accommodate mobile devices because of their enormous popularity with players and fans. They say they can't afford to be inflexible.
Both of Baldwin's playing partners acknowledged using cellphones on the course.
"I talk to my boss," said Martin Collins, a courier for a medical supply company.
Kenneth Dotter said he uses a smartphone app for a friendly weekly competition.
"You plug your scores in from our group, and it shows you a leader board," he said. "It's pretty cool."
The sport's growing tolerance of cellphones appears to be a necessary concession to the modern era as participation in the game has waned. From 2000 to 2012, the number of U.S. golfers declined from 28.8 million to 25.3 million, according to the National Golf Foundation.
With that trend in mind, the sport is endeavoring to make peace with the cellphone.
"Golf in general is flat nationwide," said Michael Dreyer, 66, head professional at the public Clifton Park course, which has no cellphone restrictions and appeals to younger players because a round is relatively inexpensive.
Dreyer said he remembers when golfers escaped to the course because of its "serenity. It used to take you away from things."
Today, he said, "we have to pretty much stay current with what's going on if we want to succeed in our business. The younger you are, the more time you spend on the phone. It's like part of your equipment. People are on the phones every minute, even on the course. Most of the time it's texting or scrolling."
At area courses, players use smartphones to measure the distance to the hole, monitor their long-term progress and track the scores of friends and rivals in real time. They also text, check emails and occasionally make calls that can be loud and slow play.
Golf always has been a self-policing sport, and Owen Dawson, the director of instruction at the Country Club of Maryland, said the club relies on members to display proper phone etiquette.
He said players are permitted to use smartphones or range finders to calculate distances.
"You're allowed to have your cellphone with you out there," Dawson said. "You're not supposed to be talking on the phone."
As cellphones' popularity grew, professional tournament organizers debated whether to permit fans to bring them along.
"You have to strike that balance somewhere," said Thomas Strong, senior director of tournament standards for the PGA Tour. "We're trying to do it in a fan-friendly way without interrupting the players from doing what they need to do."
The PGA Tour, which oversees 44 tournaments (but not the U.S. Open), began allowing fans to use their phones around courses in silent mode in 2011.
A similar change was implemented at this year's U.S. Open, which began Thursday near Seattle.
Interspersed among the fairways and dunes at the Chambers Bay course are several specially designated, rounded areas large enough to be oversized bunkers. The areas aren't hazards, but rather creations organizers hope will prove far less annoying to the competitors — "Phone Zones" for spectators to make or receive calls.
While the PGA Tour has long had such zones, this is the first time the U.S. Open has allowed fans to bring their phones. They must keep them silenced outside the zones and are prohibited from taking pictures of golfers during play.
Touring pros occasionally have had issues with fans' phones.
The year after the PGA permitted fans to silently use the devices, Phil Mickelson, Rickie Fowler and Bubba Watson were dogged by fans snapping pictures at the Memorial Tournament in Dublin, Ohio. Watson said afterward that the distractions seemed to affect the concentration of Mickelson, who shot a 79 — 7 over par.
It's common now at tournaments to see officials or volunteers roaming the course wearing bibs or vests with titles such as "Mobile Device Policy Enforcement" — the cellphone police.
After the 2012 Memorial Tournament, "we went back to the mobile device team to make sure everybody really understood the policy," Strong said. "The first line of defense is having our marshals inform the fans [of the policy]. When we get a big marquee group going, we'll actually have people out ahead of them making an announcement."
Fans at PGA tournaments are allowed to take pictures during practice rounds, but not after play begins.
"It's unfortunate that some people get really aggressive and want the picture," Strong said. "If a fan is trying to violate it, we'll address it. We'll ask them to not do it going forward. If somebody gets very aggressive with us, we could just go to the level of saying, 'We'll take your phone' or ask them to leave the property."
So much happens in a tournament at once — with golfers teeing off at staggered times and spread around the course — that smartphones can be a useful tool.
"We're so attached to our cellphones now," said Carl Stevenson, 51, of Glen Burnie, who plays golf twice a week and periodically attends tournaments. "I love using golf apps on my phone. It keeps my handicap as well as my scores."
At tournaments, he said, "this is an opportunity for the golf fan to know what's going on everywhere."
Experts say golf's participation rates have dropped particularly in recent years among people aged 18 to 34. That's a demographic wedded to their smartphones.
It's also a group, said former professional golfer Marlowe Boukis, that golf might hook by being flexible and emphasizing "fun."
"It's all about having fun," said Boukis, 28, who grew up in Lutherville and played on the LPGA futures tour now known as the Symetra Tour. Now a health care consultant, she is a former business development official with the PGA of America, which supports services to golf professionals.
When Boukis golfs with her friends, they will often link a cellphone to a speaker via Bluetooth and listen to music on the course.
"I have a client who actually just prefers to play with music going — some '80s hits or '90s or hip-hop, that kind of thing," Boukis said. "I was always of the mind that, similar to baseball, there should be walk-up songs in golf whenever you tee off."
Boukis said she exercises common courtesy, refraining from playing music when near another golfing group.
But she is adamant that the sport must continue to evolve.
"Our lives have been accessible to mobile technology," she said. "Golf is not immune from that and shouldn't be. It's here to stay so embrace it — and play the music."