The Proposal to Muffle NASCAR Race Cars

Last week, Adam Stern broke a story that NASCAR is considering 15 to 20 potential changes that would help increase the fan base. They’ve already implemented race segments and we’ve heard talk about shortening race weekends from three to two days.

Stern’s article says that one of the ideas on the table is making race cars quieter so that fans can talk to each other and socialize more during races. He notes that many stick-and-ball sports now offer places where people can stand around and congregate during games instead of (as he puts it) “Being restricted to a standard seat”.

Stern notes that, if this went ahead, the change would be done gradually and in a way that allowed NASCAR to evaluate the impacts on the racing and the fans. In other words, a way to tune the sound so that it’s “just right”. Not too loud for the sensitive millennials unable and not too soft for the existing, aging fan base.

Why Are Race Cars So Loud?

Race cars don’t have mufflers.

The reason to eschew mufflers is not so the cars will be loud. It’s because the way mufflers work slows down the airflow out of the engine. You can’t put air into the engine until the air from the last cycle is exhausted. If you slow down the exhaust, you slow down the combustion. There’s a real correlation between sound and speed. Historically, racers realized that mufflers made their cars slower. Therefore, mufflers have no place on race cars.

How Loud Are They?

Research indicates that the maximum noise level a person should experience for an 8-hour shift is 85 dB. Noise exposure is always reported in terms of a sound intensity level and a time you’re exposed to it.

The louder the sound, the shorter the time you should be hearing it. You use the graph below by identifying the sound level you’re going to be experiencing on the bottom axis, then follow it up to the line and read the maximum time you should be hearing it off the left axis. You can hear a sound of 95 dB for four hours safely, a sound of 100 dB for two hours and 105 dB for 1 hour.

Note that this graph only goes up to 115 dB because you shouldn’t be exposed to noises louder than this! That’s why you should always wear earplugs at the track.

The Data

We all know tracks are noisy, but there are people who study noise and they’ve actually measured how noisy tracks are in a way that goes far beyond pulling out a sound meter at the start of a race. NIOSH (the National Institutes for Occupational Safety and Health) is the government organization charged with researching and developing safety standards for workplaces. (Disclosure: I have collaborated with NIOSH researchers, but in nanoparticles, not sound.)

In 2000, NIOSH researchers went into a race shop and to Bristol to measure noise levels. The report and paper were followed up in 2010, where they measured noise levels at three tracks: Kentucky, Indy and Bristol. It is worth looking at the papers, if only to read how they describe a race weekend in the highly technical, specialized language of scientific journals.

The figure below the average readings over an entire race – including cautions and crashes and such – in front. The back bars are the maximum readings. They measured in the stands, the infield and the pit area. Bristol is always included in studies like this because it represents the worst case in terms of sound: It’s entirely enclosed and small. Even so, the average measurements are about the same. Note that peak measurements can be higher. Noises at 150dB have been measured at Bristol, but those are for really short times.

The next graph shows the average numbers for the first 100 minutes of three races, measured in the infield/pit area. I include that to give you an idea of how much the volume changes over the course of a race. Bristol is, indeed, louder when at the loudest and only drops to 100 dB in the quietest times during the race.

The NIOSH researchers found that, at the track, the noise reaches an unsafe level (meaning permanent hearing loss is likely) during a race:

  • In less than a minute in the car
  • In less than two minutes in the pits and infield
  • In 7 to 10 minutes in the stands .

This is why it is so important to wear ear protection at the track — and if you have kids, it’s especially important. Most drivers’ kids on pit road before the race are wearing over-the-ear headphone. Their parents know.

How Much Quieter Are We Talking?

Dale Earnhardt, Jr. (on Episode 164 of his Dirty Mo podcast) states that NASCAR is looking at decreasing the sound level of the cars from 120 dB to 90-100 dB. To understand what that magnitude of a decrease would mean requires understanding dBs.

dB stands for decibel, the unit that measures sound intensity level. The dB was adapted in the 1920s to quantify signal loss in long-distance telephone transmissions. The Bel was named in honor of Alexander Graham, but it turns out that the Bel is too large a unit for everyday use, so we use the deciBel – which is 1/10 of a Bel.

dBs are strange units. I’ve mentioned before that they are logarithmic — not linear. When you go from 10 dB to 20 dB, you’re not increasing the sound intensity by 10: you’re multiplying the sound intensity by 10.

  • When you go from 60 to 70, you increase the sound intensity by ten times.
  • When you go from 70 dB to 80 dB you make the sound intensity another ten times more. 80 dB is a hundred times more than 60 dB.
  • 90dB is a thousand times more than 60dB.

Decibels Don’t Measure Loudness

Sound intensity measures the power of the sound wave. But you are not a sound meter. Your ears are incredibly complex things. Your brain is even more complex. How loud a sound appears to you is dependent on many things.

  • Frequency. We hear some frequencies better than others. Our ears are optimized for frequencies around 2000 – 4000 Hz. A noise in that frequency range will appear louder than a noise with the same sound intensity that is outside the range.
  • How many frequencies are in the sound and how closely they are spaced.
  • Duration. We perceive noises as becoming louder with time up to about 1 second. The longer you listen to a sound, the more your ears adjust to it. This is why racing headphone companies tell you to start with the volume at zero and gradually raise the volume to the lowest level you can hear.
  • Dissonance.  Think of how you perceive a crash vs. a concert. How much we ‘like’ a noise affects how loud we perceive it to be,
  • Your mood. There’s a psychological component to loudness.

So the problem is that you can’t really convert ‘dB’ to loudness. Loudness is a psychoacoustical term, meaning that it is dependent on physical parameters we can measure (sound intensity, frequency and duration) — but it is also dependent on psychological things inside your head that we cannot measure.

You’ll see people cite a rule of thumb that so many dB = half the loudness. The problem is that not everyone agrees what this number is. You’ll find people saying an increase of 3dB or 6dB or 10dB means that the loudness doubles. Here’s the way I understand it, based largely on arguments made on this website.

  • If you double the power, you increase the sound intensity level by 3dB
  • If you double the sound pressure, the sound intensity level increases by 6dB
  • If you double the loudness, the sound intensity level increases by 10dB.

The first two of these are things you can actually measure. The last of these is not measured. It is something psychoacousticians have told us.


Psychoacousticians don’t all agree. Because they can’t measure the number directly, they infer it from the measurements they can make.

If I brought you a cake and told you the ingredients that went into it, you could probably describe what the cake tastes like without tasting it. You’ve inferred something about the cake’s taste without actually tasting it.

Since we can’t open up your brain and see what’s going on, we have to infer thing. How many dB equals an increase in loudness is inferred. So some psychoacousticians claim that an increase of 6dB doubles the loudness. Others claim the number is 10dB.  There is no consensus.

And if a group of people who have spent their lives studying this phenomenon can’t come to an agreement, I’m certainly not going to answer it. So let’s try something else.

What Would It Sound Like?

Since dB is not an intuitive quantity, we often use examples of things to communicate an idea of what each decibel level means. The graph below pulls together data between 60 dB (ordinary conversation) and 160 dB (a stun grenade: It’s very hard to find everyday examples of 160dB). I’ve colored the NASCAR-related sounds in orange.


To get an idea, therefore, of what the proposed sound changes would be like, just look at what’s down the scale.

A reduction of 10 dB

  • If they took the sound down by 10 db, then a race in the stands would go from 96dB to 86dB, somewhere between a very busy restaurant and a garbage disposal.
  • The driver’s sound intensity level would go down to 104 dB, which is between a siren at 30 years and someone shouting and inch from your ear.

A reduction of 20 dB

  • A NASCAR race in the stands that was 96 dB would be 76 dB – about the sound of a vacuum cleaner when you’re using it.
  • The sound level for the driver (inside the car) would go from 114 dB to 94 dB, which is about the sound level for the subway.

A reduction of 30 dB

  • A NASCAR race in the stands that is about 96 dB would be 66 dB – quieter than the sound of a vacuum cleaner when you’re using it and slightly louder than normal conversation.
  • The driver’s sound intensity level would go from 114 dB to 104 dB.

Would it Work?

If your goal is to allow people to talk with each other during races, 10 dB isn’t going to do it. I’ve plotted the sound intensity as a function of frequency for a male human voice (male because that was what I could find data for) and for a NASCAR race car. Remember that every 10 dB is another factor of 100. There’s a pretty big gap between car and voice. It would take a 30 dB reduction to even approach the point where you could have a conversation.

The most likely way NASCAR would accomplish decreasing the sound would be a muffler. Any regular reader of this blog knows that change is never as simple as bolting on a part. A muffler would require re-routing the exhaust. Since teams have different configurations for some tracks, it’s not one change, it’s three or four across the cars. Stern cites an estimate of a couple thousand dollars in parts per change.

But it’s not just the muffler. Mufflers restrict the engine’s airflow, so everything involving the engine would have to be re-examined. The Computational Fluid Dynamics calculations of the motion of air in and out of the cylinders will have to be re-done. When you’re dealing with something as complicated as a car, every change propagates down the line both ways. It is never as simple as changing out a part.

To me, one of the biggest reasons to watch a race at the track instead of on the television is the visceral experience. I wear earplugs from the moment I get to the track until I’m in the car to leave. I can still hear the cars, but I can also feel the sound waves in my bones and that is a feeling unparalleled. You don’t get that going to a baseball game. People and beer are the other two big reasons for me.

Is Quieter The Best Solution?

I can think of a number of good reasons why you might want to consider making race cars quieter.

  • Dealing with increasing political pressure to eliminate race tracks as sound nuisances (something tracks in Europe already face). Some tracks are being swallowed by development. Okay. We can compromise. We’ll bring the sound down a little, you stop trying to get rid of us.
  • Increasing safety by ensuring that people can hear each other and communicate effectively: Watch out! There’s a tire cart behind you!
  • Protecting the hearing of fans or — more critically — of the people who work at race tracks and are repeatedly exposed to loud noises. The average fan may attend a few races per year. A crew member does 36-39 (Duels in Daytona, all-star races). They are exposed to high noise levels for 8-16 hours a day for 2-3 days a weekend.

BUT: Making a change so that millennials can talk amongst themselves during a race is definitely not one of them. There’s a fine line between recognizing that younger people have different habits and endorsing those habits.

I went to see a production of Long Day’s Journey into Night last year on Broadway. They ran it in stages. (No flags and we call the breaks “Intermission”.) Even so, it was about three hours. There were millennials there. They were mostly quiet and attentive during the play. It’s not like they’re incapable of doing it — if they really want to.

And the fact that they don’t want to is the reason why stick-and-ball sports are giving them places to congregate where the game isn’t the main attraction. If you want to spend a couple hundred dollars on a sporting event and then treat the event as though it was on television in your living room, have at it. It’s a good change for me because it removes them from where I am. I can focus on the game — which is why I came.

The change NASCAR is considering goes beyond this: It changes the sport for everyone. That’s why it’s raised so much ruckus.

Perhaps NASCAR is overthinking this.

Perhaps a simpler solution is to make the change at the track level. Convert a couple of suites to social media havens. Put in super-fast wifi. Have free snacks. Instead of renting out the suites to organizations, sell tickets.

Then, if you want to watch the race without hearing it, you can do so with like-minded people who wish to communicate on Topics of Great Importance during the race. And the rest of us aren’t affected.

Update: A Possible Solution to Hearing Loss?

The question of permanent hearing damage related to racecars comes up once or twice a year on this blog. Last year, I explored whether an iPod was worse for your hearing than going to a NASCAR race. (It is.)

The reason people lose their hearing from going to races and not wearing ear protection is that the noise kills their hair cells. Hair cells (which are named because they look like hairs on a microscopic scale, not because they have anything to do with hair) are responsible for changing the incoming pressure waves of sound into electrical signals so your brain can process them.

Chickens and sharks can re-generate hair cells, but humans (and other mammals) cannot. The death of hair cells accounts for 90 percent of hearing loss according to the Centers for Disease Control and Prevention.

A team of scientists published a paper in Cell Reports on February 21st of this year. Here’s part of their abstract:

…using a small-molecule approach, we show significant expansion (>2,000-fold) of cochlear supporting cells expressing and maintaining Lgr5, an epithelial stem cell marker, in response to stimulation of Wnt signaling by a GSK3β inhibitor and transcriptional activation by a histone deacetylase inhibitor. The Lgr5-expressing cells differentiate into hair cells in high yield.

(I don’t expect you to understand that, just to appreciate how much work I have to do to figure out this stuff myself so I can explain it!)

Back in 2012, this research group discovered a type of stem cell in the ears that is also found in the lining of human intestines. (The cells are the Lgr5 mentioned in the abstract.) These cells regenerate once every eight days. These scientists found a way to convince these stem cells to regenerate into hair cells instead of intestinal cells.

The problem is that this process took a very long time and had a very low yield. The paper reports a new type of growth method in which they add a few chemicals and get way, way more cells (11,500 vs. 200). Note that it took them five years to figure out how to make this fairly small step. Scientific research is slow, even when done by really brilliant people.


When you read a popular report of a scientific paper, the headline is usually misleading. This story was advertised as “Scientists Regrow Sound-Sensing Cells” and “A New Breakthrough in Lab-Grown Cells Could Restore Hearing“. But if you actually read the paper…

  • The work was done in mice. Anyone who’s worked with mice knows that there are many, many cases in which something that worked really well in mice fails to work in human beings.
  • This paper reports only that they’ve figured out how to grow the cells – they don’t actually know if the cells actually work yet. That’ll probably take another three to five years. That’s the nature of research. It’s hard, it takes a lot of time and requires a lot of small people and money.

Nonetheless, this is a major advance — and good news for those of us who spent too much time at rock concerts and race tracks in our youths and are now starting to suffer for it.


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  1. “NASCAR is considering 15 to 20 potential changes that would help increase the fan base.”

    The whole idea is ridiculous (why don’t they just switch to noiseless electric cars?). As are most of the changes that were implemented to help increase the fan base (and they didn’t work, in fact these changes drove fans away). There was an article this January I think on about how 45% of the TV fanbase was lost in 12 years thanks to Brian France’s changes. This year so far all three races with the idiotic stages were all time lows in ratings.

    And why the hell would anyone want to socialize during a race (oh, wait, since the product is boring as hell! that explains it)? People go the the theater to watch a play or socialize? Tell the stage actors to keep it down? Maybe the cinemas should also go back to silent movies with subtitles and no music, so people could socialize (by te way, they do and it’s called texting).

  2. I would like to see NASCAR and one of their touring series (Cup/Xfinity/Trucks) at least try an experiment, working with whatever exhaust supplier(s) would be interested in working on this–trucks might be best, considering the room available, but that series is the least-able to afford changes, so it needs to be a sponsored deal–and the muffler(s) would need to be the same for all, so the impact is universal. Short tracks–especially Bristol & Martinsville/or anything 1-mile or shorter–ought to be the initial focus, since a lap is SO short that the rate at which cars are passing a fixed point (ie. a spectator position) is much higher at these tracks. Granted, there is a good deal of off-throttle time at these shorter tracks, but the proximity of cars & spectators sitting closest to the track would be interesting to study in a test of reduced exhaust decibel methodology–Turn 3 at Bristol, first row, for 200 laps of trucks without ear plugs or muffs was NOT fun, or good for my hearing. I remember a Wood Bros Mercury from YEARS ago at Ontario–about 1974–when David Pearson was the driver. This car, even though it didn’t have mufflers (to my knowledge), was notably quieter than all of the other cars…and I’ve often wondered what design features can influence what the exhaust sound and it’s intensity are going to be–that car would have been running a 358″ Ford Cleveland or Windsor, or possibly a 427, but RPM would have been in the 7000-7500 range. BTW–there are plenty of race cars with mufflers, contrary to one of the opening statements made by DLP.

    Here’s an excerpt from “down under”:
    Virgin Australia Supercars (formerly Australian V8 Supercars)
    Supercars Operations Manual – Technical Rules

    Exhaust System

    Paragraph C8.4

    “Each Car must be fitted with effective mufflers which diminish the sound of the engine exhaust noise so that the maximum exhaust noise does not exceed 95dB(A) measured at 30 metres from the side of the Circuit by approved measuring equipment”

    While I’ve not attended a VASC event, I’ve seen them on TV, and they seem to be well-attended, and the sounds the cars make seem pretty racy–5.0L, fuel injected, 7500RPM max engine speed, about 650HP–how much more sound does a NASCAR 5.8L engine running up to 9000+ RPM make in comparison? I don’t know….but can (you) imagine a race with low-enough exhaust noise where you could actually hear the tires howling as they strained for grip? That would be very interesting, IMO…..

    • Love this idea – especially how well you’ve thought out what type of track would be the ideal for testing your theory!

  3. YOU HAVE GOT TO BE THE ENERGIZER BUNNY TO BE STILL DOING THIS AFTER ALL THESE YEARS. I hope the fans realize how much work goes into each of these blogs and how lucky they are to have you explain in terms the average person can understand the complicated subjects you explore. Thank you. I’m still vertical, so still learning.

  4. On The Morning Drive (SiriusXM) today, a caller was talking about how loud it was at Bristol. Lots of empty seats didn’t help, but I re-state the case that safety & health considerations ought to bring some people to their senses about the sound levels encountered in racing–as much as the typical race fan “likes” the assault on his or her senses, it doesn’t do anything good in the long run. The teams–crews & drivers–are doing this for 36 weekends. Has anyone asked them whether they would support or oppose a 95-decibel limit?

    • NASCAR is concerned about the noise issue for multiple reasons and I know they’re looking at solutions that could decrease noise without angering their core fans.

      The simplest thing they could do (well, it would be the track, but NASCAR could help fund and publicize it) would be an awareness campaign. Offer free earplugs at the track. Get FOX to do a segment on how important ear protection is. Have drivers talk about their own damaged hearing and how it can be prevented.

      Even cheap foam earplugs make a huge difference in cutting noise and preventing hearing damage. And since sound travels faster is solids — like bone — than air, you still get the visceral feeling we all love when you feel the sound through your body. That beats having your ears blasted out in my opinion.

      This seems like a simple idea with little downside and little cost, doesn’t it?

      Thanks so much for reading!

      • I do agree–convincing people is an entirely different matter, so I still believe that some venues–as previously mentioned, at least the short tracks, ought to be looking at ways to reduce the impact of the intensely high noise levels on not just the folks in the stands, but everyone present. I don’t even want to start talking about the carbon monoxide concerns, which potentially impact drivers the most, and there are scrubbing devices some have tried….topic for a separate discussion. The concerns about mufflers as far as changing the nature or character of the on-track “product” are simply resistance to a change that technology has offered solutions for long ago, and it’s about time that something is done. The reduced power argument is just ridiculous–the cars/trucks have way more power than they used to have, and way more than is needed for good racing. Sound attenuation/reduction measures in NASCAR would ultimately be good for lots of reasons.

  5. Very informative article. I wondered which source was used for the graph titled “Sound Levels at Different Frequencies”, it would be very helpful (for me) to look in to this information deeper. Thanks!

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