Matt Valentine is a writer living in Austin, Texas.

When gunfire rang out over the Route 91 Harvest festival Sunday night in Las Vegas, the rapid, sustained tat-tat-tat-tat was clearly audible, even over the live music booming from the stage. Some attendees initially mistook the sound for fireworks, a pyrotechnic finale to the concert. But as bodies began to fall, the terrible reality was soon clear: The thousands gathered that night on the Strip were under attack, in what would become (for the time being) the deadliest mass shooting in U.S. history.

Concertgoers huddled under whatever shelter they could find—behind vehicles and flimsy fences, inside a caterer’s freezer, behind concession stands—some shielding loved ones with their own bodies. They couldn’t see the gunman in his perch on the 32nd floor of the Mandalay Bay hotel, but they could hear the sharp report of his rifle. In amateur video captured from the crowd, the camera pans up to the Mandalay Bay, across the street from the outdoor concert venue. A few men and women can also be seen pointing up toward the source of the shooting. One man, still holding an oversized can of Bud Light, flashes his middle finger up at the hotel before ducking for cover. Ben Sweeney, a hotel guest on a business trip, told the Washington Post that the resounding gunfire seemed to have been coming from the adjacent room. (He wasn’t far off in that estimation—the gunman was two floors above Sweeney and one room over.)


In an interview with CNN, Las Vegas Undersheriff Kevin McMahill said that officers on the ground “could actually hear where the rounds were coming from,” and coordinated their response accordingly. (A fire alarm, triggered by smoke from the gunfire, further helped police to pinpoint the specific room where the gunman was located.)

This latest mass shooting—in which the sounds of gunfire played an important role for survivors and police—coincides with an effort in Congress to deregulate gun silencers, devices that reduce the volume of a gunshot by capturing and dispersing hot gas as it leaves the muzzle of a firearm. Under longstanding law, silencers are sold only by specially licensed dealers and are subject to more rigorous background checks, longer waits and steeper federal taxes than typical gun sales. Lobbyists for the firearms industry, affiliated with both the National Rifle Association and the National Shooting Sports Foundation, have argued that making guns quieter is a simple matter of public health. Quieter guns are less likely to cause hearing damage.

But gun violence prevention advocates from groups including the Violence Policy Center and Brady Center have challenged those safety claims and pointed to another motive for the push to deregulate silencers—profit. There are more guns than people in the United States, and recent slumps in gun sales might be a sign that supply is outstripping demand. For consumers who feel they already own enough guns, a silencer might be a more likely purchase—especially if Congress eliminates the $200 tax and months-long wait to acquire one. Senator Chris Murphy, who represents the Newtown community still devastated by a mass shooting in 2012, articulates that calculus in a recent Huffington Post video. “The gun industry will do better,” Murphy says, “but lives will be lost.”

The first commercial silencer was patented in 1909, and they were still relatively novel in 1934, when Congress enacted the regulations still in effect today. Together with fully automatic machine guns, sawed-off shotguns and some other weapons, silencers were restricted under the 1934 National Firearms Act, which was written with the participation and approval of the NRA. The legislation was a response to the shocking violence of gangland massacres, in an era where criminals often outgunned police.

A century later, silencers are making a comeback, part of a growing market of “tactical” equipment popular with consumers. Consumer interest in tactical equipment seems largely motivated by aesthetics, rather than actual application. For example, several gun manufacturers now offer real guns with fake silencers, such as this .22 caliber GSG handgun for sale in Utah or this Uzi from a Texas online gun retailer. (These faux suppressors don’t affect the volume of gunfire at all, but some gun buyers think they look cool.) The tactical weapons industry has been flexing its political muscle recently, fighting restrictions on “armor piercing” ammunition and high capacity magazines. According to Federal Election Commission filings, a Texas based retailer called the Silencer Shop contributed $10,000 to Team Ryan in November, a political action committee associated with House Speaker Paul Ryan. David Matheny, who owns the Silencer Shop, also made an individual $10,000 contribution to the PAC.

In June, Congress was set to consider a bill to eliminate stringent regulations on silencers, but postponed hearings after a shooting spree at a baseball practice left Rep. Steve Scalise and three others wounded. Discussion of that legislation was expected to resume this week, but congressional leaders told Politico that Sunday’s shooting might further slow the progress of the bill.

The prospect that unregulated gun silencers might soon be sold at any sporting goods store or Wal-Mart, though, remains entirely plausible. The Hearing Protection Act has 165 sponsors, including four Democrats. And it’s all but certain that President Donald Trump would sign the bill if it reaches his desk—the legislation is backed by the NRA, which spent more than $30 million in support of Trump’s election. After trying out several silencers produced by Utah-based SilencerCo, the president’s son, Donald Trump Jr., said the quieter shooting experience might make guns less intimidating for kids. “There’s nothing bad about it at all,” the younger Trump said in a video.

The NRA is quick to challenge the common misperception that silencers make firearms whisper-quiet. Indeed, many gun rights advocates object even to the term “silencer” (preferring “suppressor”), because guns equipped with such a device are not actually silent. In a feat of impressive self-contradiction, the NRA’s lobbying arm published an article last week explaining that guns with silencers are as loud and conspicuous as jackhammers, but also gentle on the ears. Both points are reiterated by Doctors for Responsible Gun Ownership in a position paper endorsing easier access to silencers. (The gist: guns are noisy.) The term “silencer,” though, is used by various law enforcement agencies, appears in state and federal legislation, and is commonly used by retailers and manufacturers of these devices. Inventor Hiram Maxim called his original design a silencer.

It’s true that, depending on the caliber and type of ammunition, as well as the design of the silencer, even a suppressed firearm can be painfully loud. Without the addition of grease or gel (which can further dampen sound), a quality suppressor might reduce the sound of a gunshot by about 40 decibels. For a large hunting rifle, the shooter would still need to wear earplugs or earmuffs or risk hearing loss. Smaller caliber weapons using lower-velocity ammunition can produce a dramatic drop in volume when a silencer is attached. In a video published by the news website AL.com, shooter Joe Songer demonstrates the range of volume one rifle can produce with various types of ammunition and a suppressor. With low velocity ammunition, the gun is astonishingly quiet. “Basically, all you hear is the bolt cycling in the gun,” Songer says. “You don’t hear the crack.”

Jim Pasco, who heads the Fraternal Order of Police, told Politico in September that gun silencers are not “a law enforcement problem,” which is why he supported the congressional bill that would make them easier to obtain. But the National Law Enforcement Partnership to Prevent Gun Violence argues that the reason silencers are seldom used in crime is precisely because they have been effectively regulated for more than 80 years. The partnership, which includes the Police Foundation, Major Cities Chiefs Association and six other police groups, warns that “the widespread and uncontrolled distribution of silencers to an unwary civilian population, combined with the sheer number of firearms freely available in America, is a step in the wrong direction and will result in tragedy, including violence directed at police officers that will be difficult or impossible to investigate effectively.”

According to a 2015 criminal complaint filed in the U.S. District Court for the Eastern District of Virginia, Samy Mohamed Hamzeh attempted to purchase automatic firearms and suppressors for a suspected terror plot. “I am telling you, to go without silencer gun, you will be exposed from the beginning,” Hamzeh is alleged to have said before his arrest.

The role silencers can play in crime is not entirely hypothetical. In a handful of real-world incidents, silencers have stymied law enforcement.

In 2014, police in Smyrna, Georgia, responded to reports that a man had been seen with a gun and might have a hostage in his home. They arrived on scene and began a 14-hour long standoff with Antoine Davis. Because he used a silencer, no one heard the gunshots when Davis killed Jessica Arrendale and then himself. Eventually, police used a robot to explore the interior of the home, where they found Arrendale’s baby hidden in a toilet, alive but suffering from hypothermia.

In 2013, former police officer Christopher Dorner used a 9mm handgun and silencer to kill Monica Quan and Keith Lawrence in Irvine, California. The attack occurred around dinnertime in a neighborhood full of condos and student housing; people were certainly in the vicinity of the crime scene (a parking garage near the UC Irvine campus), and yet nobody reported hearing the 14 gunshots. Later, during a manhunt and standoff, Dorner fired a suppressed AR-15 rifle at officers in two separate locations. Police eventually recovered 10 silencers belonging to Dorner.

In 2015, Robert Dahl chased his business partner Emad Tawfilis through a vineyard in Napa Valley, firing at him repeatedly with a handgun that had been fitted with a silencer. Nobody called 911 to report the sound of gunshots. Police responded only when Tawfilis himself called to say he was under fire. They arrived in time to see Dahl execute Tawfilis at close range.

Timothy Moore had been missing for five months before his remains were discovered on a logging road near South Bend, Washington. His 16-year-old son had transported the body there after killing him with a .22-caliber rifle equipped with a silencer. Though Devon Moore fired the gun several times, neighbors hadn’t heard a thing. (They were home at the time of the murder, and recalled seeing someone hosing out the family pickup truck later that morning.)

Of course, even when people do hear the sound of gunfire, they don’t always alert police. According to the Brookings Institution, 911 callers in densely populated urban areas inform police of only about 12 percent of gunfire incidents. Technology, though, has been deployed in some high-crime areas to listen for gunfire using specially designed audio sensors, so that police can be dispatched to the scene of a shooting even when no one has called to report it. This system, called ShotSpotter, has been used in Washington, D.C., and in several cities in California, New York, Ohio, Illinois and Texas. In a 2006 field test of ShotSpotter conducted by the National Institute of Justice, the system detected 99.6 percent of 234 gunshots at 23 locations. All of the test fire came from firearms without silencers. Asked by the New York Times whether the system would work for guns with silencers, ShotSpotter’s Vice President Gregg Rowland shrugged off that concern, replying, “this does not happen very much in the real world.” It might be a more common occurrence, though, if Congress removes the regulatory obstacles and the federal tax that make silencers difficult to obtain and prohibitively expensive.

In a televised statement from the White House on Monday, President Donald Trump credited the quick response of law enforcement for ending the Las Vegas shooting spree and saving lives. The attack ended just as SWAT breeched the door of gunman Stephen Paddock’s hotel room, at which point he apparently took his own life. There were hundreds of rounds of unspent ammunition recovered at the scene, among an arsenal of firearms. “The speed with which they acted is miraculous, and prevented further loss of life. To have found the shooter so quickly after the first shots were fired is something for which we will always be thankful and grateful,” Trump said.

He made no mention of the circumstances that aided that response.