One product that most car audio retailers offer that can benefit anyone with a car, truck or SUV is sound deadener. If your vehicle is noisy inside, gets hot quickly or people have trouble hearing you during hands-free phone calls, applying sound deadening can help dramatically. In this article, we’ll explain how sound deadening works and talk about the key benefits of adding damping material to your car, truck or SUV.
What is Sound Deadener?
If you have ever had the opportunity to look under the carpet or trim panels inside your car or truck, you may have seen patches of rubber or strips of butyl adhered to the body panels. The addition of this material by the automobile manufacturer adds mass to the metal panel. This added mass makes it harder for noise outside the vehicle to vibrate the panel and transfer noise to the interior of the vehicle.
Aftermarket sound deadening products work the same way. Most sound deadening is sold in sheets or rolls. The material is very dense and has one surface that includes a strong adhesive. Your installer can apply the material to flat metal surfaces like the doors, floor, roof, firewall, rear fenders and trunk of your vehicle.
Many damping materials like Dynamat Xtreme, Stinger RoadKill Expert, Wirez Premium Sound Deadening and Hushmat Ultra include a layer of aluminum on top of the flexible base layer. This aluminum adds strength to the damping material and allows it to span openings in door panels.
Some damping materials include a layer of closed-cell foam on top of the aluminum layer. Focal BAM and SoundSkins Pro are two common examples of damping materials with foam. Wirez, Dynamat and several other companies offer foam on its own as another option. This foam layer helps to reduce vibrations and rattles from objects touching the damping material. Under floors, it can prevent wire harnesses and cabling from buzzing. In doors, it prevents the rods that activate the door release mechanism and locks from rattling.
Another option for sound deadening is a spray-on solution. Cascade Audio Quiet Kote, Boom Mat Spray-On and bedliners like Line-X are a great way to add mass to flat metal surfaces.
Sound Damping Materials Make Your Vehicle Quieter
Several years ago, we took part in a test of the noise reduction capabilities of sound deadening material. The vehicle in question was a 2007 Jeep Grand Cherokee SRT with the 6.1-liter Hemi. The test started with three baseline measurements of the noise inside the vehicle. We took SPL measurements with the vehicle at idle and cruising at 40 miles per hour and 60 miles per hour. Happy with the measurements, we applied a layer of aluminum-backed damping material to the inner and outer door skins of the truck and repeated the measurements. Impressed by our findings, the last step was to treat the cargo area of the Jeep and repeat the tests once again. As you can see from the chart below, the results are impressive.
Condition Idle Cruise a 40mph Cruise at 60mph
No Deadening 88.5dB 99.0 dB 103dB
Doors 87.9dB 98.1dB 101.4dB
Doors and Cargo Area 84.7dB 94.3dB 98.7dB
Total Noise Reduction -3.8dB -4.7dB -4.3dB
Had we chosen a vehicle that came from the factory without a moderate amount of sound damping, the results would have been even more impressive.
How a Quieter Interior Improves Your Sound System
If you look at any of the sound deadening manufacturers’ websites, it will quickly become apparent that they all claim that adding sound deadening will improve the performance of your sound system. This is absolutely true and it helps in two unique and different ways.
First, by simply reducing the background noise in your car or truck, you improve the effective signal-to-noise ratio of your stereo. What does this mean? Having less background noise makes it easier for you to hear the quiet parts of your music. Imagine if you were listening to a track at a volume level of 100dB. If you have background noise level of 95 dB, any portion of the song that is around the 95dB level will have to battle with the background noise to be heard. If you can reduce the noise level in your car to 90 dB, you can hear more of your music.
The second and perhaps the most significant benefit of sound deadening is to improve the effectiveness of the speakers in your vehicle. In most cases, the doors of your car, truck or SUV have a hole in the inner skin for the speaker, and access holes for the window regulator, door handle and locking mechanism. A speaker produces an equal amount of sound from the front of its cone as from the back. If these two sound sources mix, they cancel each other out. This cancellation happens most often in lower frequencies, say below 300 Hz.
If you were to compare the in-car frequency response of a speaker mounted in the factory door location to that of a vehicle where a layer of sound deadening has been applied to the inner surface of the door, you would see a dramatic increase in bass output.
The graph below shows this very test in that 2007 Jeep Grand Cherokee. The effective output from the factory-installed 6×9 woofer increased by a jaw-dropping 8dB at 240Hz. The gains were visible for all frequencies below about 400Hz, which was, in this application, likely the upper crossover frequency of the speaker.
Another cool new product designed to help improve the performance of your sound system is Stinger’s RoadKill Fast Rings. These rings mount around the face of your door or rear parcel shelf speakers and seal up against the trim panel. The concept is that they help to channel all the sound from your speaker into the interior of the vehicle, rather than allowing it to bounce around inside the door. The rings also help reduce panel vibrations for better sound performance.
Sound Deadening Can Make Your Vehicle More Comfortable
If you watch TV shows like “Detroit Muscle,” “Truck Tech” or “Overhaulin’,” you’ve undoubtedly seen the guys apply a thorough layer of sound deadening material to the floor of some of the coolest hot rods ever. Not only do these materials help keep your vehicle quiet, but they also help block heat from the road, engine, transmission and exhaust from heating up the interior of your vehicle. Dynaliner from Dynamic Control of North America, D-Mat from Design Engineering and the aptly named Heat Barrier from Thermo-Tec are specifically designed to prevent heat transfer into the interior of your vehicle.
What to Look For When Buying Sound Deadener
Most shops latch onto a particular brand of sound deadening material that they find effective and reliable. In most cases, you can trust their choice. If you want to get picky, the most important aspect of choosing a high-quality damping material is to select one that will stay adhered to your vehicle.
There are two common problems that occur with damping materials. First, they simply may not have a strong adhesive or they require extensive surface preparation to stay adhered to a panel. Some damping materials will stick to slightly dusty surfaces without any problems. The second and more important concern is that the material itself is thermally stable. You don’t want the deadening to peel off when it gets hot in the summer. We’ve heard of many cases where vehicle carpets and headliners have needed to be replaced because damping materials turned to a liquid and contaminated them.
Install Comfort in Your Vehicle Today
If you want your car doors to close with a thud instead of sounding tinny, if you want to reduce the road and exhaust noise in your car or you want to improve the performance of your hands-free phone system, drop by your local mobile electronics specialist retailer and ask about having sound deadening installed in your vehicle. We know that you will be thoroughly impressed with the improvement.
This article is written and produced by the team at www.BestCarAudio.com. Reproduction or use of any kind is prohibited without the express written permission of 1sixty8 media.
In a nutshell, a DSP uses a microcontroller that is designed specifically to manipulate audio signals in the digital domain. Pretty much all of the DSP devices on the market include crossovers, equalizers and signal delay features that we can use to optimize the performance of your sound system.
At the simplest level, a DSP can be considered a glorified yet extremely precise tone control. When you combine the features of a processor with measurements from a real-time analyzer, a properly trained technician can dramatically improve the tonal balance and accuracy of your audio system. Vocals and instruments will sound more as though you are in the presence of a live performance as opposed to listening to a recording. Expert technicians can use stereo equalization to improve the staging and imaging characteristics of your sound system, helping to increase the realism of the listening experience further.
Let’s continue with our three-way system example. In many systems, the tweeters are mounted at the top of the door, in the sail panel, in the dash or on the A-pillar. Midrange drivers in a system like that are typically 6.5 inches in diameter and are installed in the factory door location. Finally, woofers typically require an enclosure and are mounted in the trunk, cargo area or under the rear seat of a pickup truck. The distance between the listener and each speaker is different, as is the difference between the left and right speakers. These pathlength differences result in us hearing the closest speaker first, which makes our minds think that that is the source of the majority of what we are hearing.
Well, yes and no. Good quality processors start around $400 plus installation and require at least an hour to configure in most vehicles. If you have a complex multi-channel system, you may need a DSP with more input and output channels and additional time to configure the system in your vehicle.
If you are like most people, you may think that your local car stereo shop specializes in custom audio systems, speaker replacements and, if they have marketed themselves well, remote car starter installations. The reality is, many mobile enhancement retailers offer a variety of automotive enhancement services that extend well beyond audio system sales and service. Let’s have a look at some of the service options that don’t get talked about as often. (Editor’s note: Not all of these services are available at every mobile enhancement retailer.)
Many new cars and trucks come from the dealership with advanced collision avoidance technologies. The most basic is a rear-vision camera system or parking sensor system that can alert you to the presence of an object or person while maneuvering your vehicle. If your vehicle doesn’t have a backup camera or parking sensors, a system can be added quite easily.
In the same vein as the parking sensors, an aftermarket blind-spot monitoring system will alert you to the presence of a vehicle or object beside or just behind yours. When an object enters this space, a small indicator will illuminate to alert you to an object in your blind spot. If you activate the turn signal, an audible warning will be produced to let you know that someone is there.
If you have an older vehicle or are interested in changing the look of your interior, your local mobile electronics specialist retailer can provide you with a complete custom interior. Companies like Katzkin, Leatherseats.com and Roadwire offer vehicle-specific seating upholstery in a variety of colors and patterns, including your choice of thread color. They can often embroider a logo into the upholstery if you wish. Many shops can also swap out the carpet in your vehicle with a new custom-molded piece in a variety of colors to complete the transformation.
Who better to install aftermarket 
A variety of new vehicles are still available without cruise control. Whether you have a classic car with a carburetor, a new vehicle with drive-by-wire throttle or something in between, aftermarket cruise control solutions are available to make your next long-distance trip a lot more comfortable.
Are you in the market for a set of side-steps, a new toolbox for the truck bed, a new tonneau cover or an off-road-ready grille guard? Drop by your local mobile enhancement retailer. In addition to being experts at automotive electrical systems, most shops have the tools and experience required to install a variety of truck accessories.
If you want to know where your vehicle or fleet of vehicles is at all times, a 
Do you have a power window that won’t roll down, a door that doesn’t lock when you press the button on your remote, or an intermittent instrument cluster? The advanced troubleshooting experience that most mobile electronics technicians possess far exceeds that of some dealership service centers. If there is something electrical or electronic not working on your vehicle, drop by and see if they can help.
If you live in a state or province that allows the use of radar detectors, the team at your local car stereo shop is far and away the best choice to integrate a premium system into your vehicle. Custom installed radar detectors and laser defense systems provide early warning against police radar and can delay laser measurement devices from obtaining a speed reading.
Having the windows of your vehicle tinted does a lot more than simply change the style of your vehicle. Window films block almost all of the ultraviolet energy from the sun to protect the occupants from accelerated skin aging. Premium films offer infrared rejection properties that help to keep the interior of your vehicle cooler. Window tint can also make your vehicle safer. If you get into an accident, the resulting tiny pieces of glass will remain adhered to the film rather than flying across the vehicle. Finally, window tint can help to reduce crimes of opportunity. If someone can’t see the contents of your vehicle, there is less reason for them to break in.
Many retailers offer automotive accessories like floor mats. One of the most popular brands in this category is WeatherTech. Their premium Floor Liner solution features a high-quality protective mat that is molded to the floor of your vehicle. The mat extends up the firewall and the center console to protect your carpet from damage, dirt and salt stains. WeatherTech also offers side window deflectors, mud flaps, bug deflectors and much more. Even if your local retailer doesn’t carry the WeatherTech brand, they should be able to source a solution to keep your vehicle looking great.
Are you looking for a set of lowering springs, a computer programmer or maybe a supercharger or turbo kit? Many mobile electronics retailers have technicians available to enhance the performance of your vehicle. A bolt-on exhaust, cold-air intake, high-flow air filter or throttle body spacer can provide your vehicle with a little extra power and may improve your gas mileage at the same time.
When it comes to creating an audio system that sounds amazing, incorporating a digital signal processor into the system gives your installer the tools required to compensate for the majority of the limitations that vehicles impose. To maximize the benefit, a digital signal processor system design needs to take the features and benefits of a processor into consideration. In this article, we are going to explain some of the key differences between a system with and without a digital signal processor.
A digital signal processor, also called a DSP, is an audio processor that uses a microcomputer to make adjustments to a signal in the digital domain. In a stand-alone processor, the audio signal from the source unit is converted to a digital data stream using an analog-to-digital converter. Once in the digital domain, the processor can equalize, filter and even delay the signal. Most processors have six or more output channels to provide us with the ability to send different signals to dedicated amplifier channels. Each channel has a digital-to-analog converter that provides a conventional analog audio output.
When you think of the stereotypical 
The monologue introduction to “Boom Boom Pow” by will.i.am builds to a crescendo from the 45-second mark, peaking with infrasonic information from :50 to 1:03. Content during this time extends solidly down to 7 Hz. There is another drop at 2:18, and the section from 3:13 to 3:42 contains a lot of infrasonic content. If your system is up to the challenge, this track has it all: a solid conventional bass line and enough content below 20Hz to make any true basshead happy!
Often referred to as Bass Check, “Hoods Run Down” by Lil Wyte is a rap song that starts with an introduction and the DJ plays five sequentially lower tones. The first is centered at 41Hz, and most factory sound systems can handle this one with no problem. The second “beat” is at 35Hz, and you are going to need at least a small sub to catch this one. The third drop is centered around 27Hz and will tax premium factory systems and aftermarket systems tuned to boom rather than rumble. Now things are getting fun! The second-to-last tone is centered at 20Hz and is going to be a workout for most vented enclosures. Pay attention; speaker damage may ensue! The last beat is centered around 16Hz. You are going to need serious cone area and power to feel this one with any authority. The rest of the song continues with a standard bassline with information around 30Hz. A good workout for your stereo and a nice gentle massage for the ride home.
Another classic rap track, “3 A.M.” features a steady bass line that extends down to around 30Hz, giving almost any sound system a chance to sound great. Interspersed randomly through the track are bass drops down to the single digits. There is lots of 9Hz content at the :57 and 2:01 marks. These don’t last long, but they are reasonably loud. You’ll hear 10-cycle beats at 0:37, 1:03, 1:54, 2:45, 3:11 and 3:37. There is lots of 50Hz content during these drops, so it might be hard to pick them out, but they are there.
This is more of a demo track than a song. Included on The Great Fantasy Adventure Album with main title themes from movies like Terminator 2, Clash of the Titans, Total Recall and The Abyss, “Jurassic Lunch” is a short 1:11 track at the end of the album. The track starts with birds chirping in the jungle. At the 13-second mark, a series of pulsations centered at 12Hz and 24Hz start. These continue to the 29-second mark, where harmonics are included that provide content above 30 cycles. It’s only then that you realize you are hearing the footsteps of the Tyrannosaurus rex stomping through the Jungle. Around the 39-second mark, you start to hear tree branches breaking with each step, and then at the 45-second mark, the roar of the Rex overpowers the track as he devours his prey. Of course, Kunzel included lots of bone-cracking and crunching around the 51-second mark. The Rex savors his meal from the 51- to 56-second mark, where he rewards himself with a giant burp that peaks with information down to 10Hz at the 59-second mark. This track serves as an awesome demonstration of a true subwoofer system.
This remake of “White Rabbit” by Jefferson Airplane features the required tuned PVC tubing percussion that has made Blue Man Group so unique. Though this track doesn’t share the intense infrasonic peaks of our other suggestions, it maintains an impressive level of 15-cycle content throughout the almost three-minute-long track. There is very evenly dispersed mid-bass energy in this track as well — a great challenge for your door speakers.
Another fun track from The Great Fantasy Adventure Album is the Terminator theme. This haunting track is full of special effects and mechanical sounds that remind listeners of the end scene of Terminator 2 as the machine slowly lowers himself into the mass of molten steel in the refinery. While most of the percussion comes from kettle drums in the 47-48 Hz range, the closing of the track features an explosion that starts at the 3:11 mark and peaks with 11Hz information from 3:14 to 3:16. A fitting ending to a great track.
This track goes back, waaaay back! Scholars think that Bach wrote this classic piece of organ music between 1704 and 1750 (when he died). Even those who don’t listen to classical music recognize this track. Don Dorsey released Bachbusters, a synthesizer-based take on some of Johann Sebastian Bach’s greatest pieces, in 1985. The album took first place on the Billboard classical music chart and has been popular with car audio enthusiasts ever since.
There had to be some dubstep in this list somewhere, right? “Centipede” is a somewhat creepy track that is full of fun bass. While the focus of the bass line is around 40Hz, the track contains content with good output levels down to the 10Hz range. While we doubt most clubs could reproduce this infrasonic information with serious output levels, the sensation of listening to this in a well-designed mobile audio system would be fantastic. It’s also really loud: The VU meters remain pinned at the 0dB mark for the majority of the track.
Another all-time-classic classical recording is Tchaikovsky’s 1812 Overture. This recording is known for its jaw-dropping cannon blasts at the end. When played back on a vinyl record, all but the very best turntable configurations will result in the needle jumping out of the track as the cannons go off. The first five cannon blasts appear at 12:36 into the track. The second and most impressive group begins at 14:41, with the blast at 14:55 containing low-frequency energy that extends down to nearly DC levels. Call it one to two Hertz if you want – it makes no difference.
“Purple Lamborghini” won a Grammy Award for Best Song Written for Visual Media. This rap track contains a bass line that is centered around 38Hz for the majority of the track. But the fun doesn’t stop there: Four times in the track, the bass sweeps from 50 down to 22Hz with impressive output. The video features Rick Ross, Skrillex and none other than Jared Leto in full Joker garb.
“Put On” makes our list with what we’ll call an honorable mention. The track doesn’t dig hard into the infrasonic region but contains four drops that repeat through the entire track. The first is up at 55Hz and is classic rap music bass. The second is at 44Hz and the third is at 36Hz, giving your body a nice massage. The last is centered around 27Hz and will give your subwoofers a good workout. We included this track because the 27Hz bass line appears no less than 22 times in this 5:21-second track.
The second of our three Honorable Mention tracks is “This Means War” by Avenged Sevenfold. This rock track opens with well-recorded percussion and guitar. At the 25-second mark, there is a rumble of thunder with great content down to 20 Hz that slowly fades to the 30-second mark. The remainder of the track only gets down to about 40Hz, but the kick drum is well-recorded and the entire track is well worth listening to.
Another honorable mention is Lorde’s “Supercut.” Though the main bass line remains focused between 40 and 60 Hz for the majority of the track, the section of the song from 2:34 to 3:05 has a surprising amount of information that extends down to 10 cycles at a moderate level.
Winning our “what the heck is that doing there?” award is “Supermarket Flowers” by Ed Sheeran. This track features Sheeran accompanied by a piano for the majority of the track. At the 2:08 mark, a synthesizer comes in to add some a gentle bass line to the track. The lowest notes are 28Hz at the 2:32 mark. While not the infrasonic content we were searching for, this remains a nice surprise in what would be described as a nice song.