Friday, April 27, 2007
Sound Damping
Sound damping is essential to reduce resonant noise coming from vibrations from big panels of thin metal. Examples of big panels of thin metals on the car are roof and doors. Ever wondered why the rain noise in certain cars are louder and more irritating (e.g. Nissan Sunny) and the rain noise in some cars are much muffled (e.g. new BMW 3 series)? Heard of anyone who hit the chinese 'Gong' repeatedly? What happens when you grab the 'Gong' immediately after you hit it?
The answer is simple, our hands damped the 'Gong' immediately to reduce all the vibrations on the 'Gong' that produces the sound. The harder you grab the 'Gong', the faster the vibrations is reduced and the faster the sound is reduced. Applying this concept on the doors and roofs of the cars and we can effectively reduce the noise from the roof when it rains and the loss of sounds through the doors.
This implies that the heavy bitumen type of material is the best in damping. However, its insufficient if its just damping alone, as there are still noises intruding the car cabin due to lack of noise absorption. Which brings me back to promoting my soundproof material, it effectively dampens and absorbs any residual noise. It damps the roof as well as the bitumen by the use of mass and pressure created by the roof carpet (See illustration below).
In this way, the roof carpet pushes the 2 layers of soundproof material against the roof to increase the damping effect. At the same time, with the absorption factor in the Superlon foam, most of the residual noise is absorbed.
For the doors, another set of physics is working against the driver's ears. Without any soundproof on the door panels, vibrations set in from various sources. One major source of this is noise coming from the outside e.g. motorbikes beside your car. Another source of vibration is from the speakers' backblast. When the speakers are producing sounds, there is an almost equal amount of air column hitting the bare door panels, thus introducing vibrations to the car doors. To reduce these vibrations, the Superlon material works well to reduce and reflect the sound back into the car cabin, thus improving the bass and reducing the loss in sound energy, creating a better experience for the driver.
The answer is simple, our hands damped the 'Gong' immediately to reduce all the vibrations on the 'Gong' that produces the sound. The harder you grab the 'Gong', the faster the vibrations is reduced and the faster the sound is reduced. Applying this concept on the doors and roofs of the cars and we can effectively reduce the noise from the roof when it rains and the loss of sounds through the doors.
This implies that the heavy bitumen type of material is the best in damping. However, its insufficient if its just damping alone, as there are still noises intruding the car cabin due to lack of noise absorption. Which brings me back to promoting my soundproof material, it effectively dampens and absorbs any residual noise. It damps the roof as well as the bitumen by the use of mass and pressure created by the roof carpet (See illustration below).
In this way, the roof carpet pushes the 2 layers of soundproof material against the roof to increase the damping effect. At the same time, with the absorption factor in the Superlon foam, most of the residual noise is absorbed.
For the doors, another set of physics is working against the driver's ears. Without any soundproof on the door panels, vibrations set in from various sources. One major source of this is noise coming from the outside e.g. motorbikes beside your car. Another source of vibration is from the speakers' backblast. When the speakers are producing sounds, there is an almost equal amount of air column hitting the bare door panels, thus introducing vibrations to the car doors. To reduce these vibrations, the Superlon material works well to reduce and reflect the sound back into the car cabin, thus improving the bass and reducing the loss in sound energy, creating a better experience for the driver.
Monday, April 23, 2007
Noise barriers
To achieve the noise barrier result in automotive context, the noise must either be effectively contained or just being isolated from the car cabin. This effect can be achieved by using materials which are close-cell structured to prevent any 'leakage' of noise into the problem area.
This concept can be applied to the following parts of the car:
1) 4 doors to reduce exterior noise e.g. motorbike exhaust noise.
2) Steering wheel column and front floor to reduce exterior noise e.g. engine noise and front undercarriage noise.
3) Wheel arches to reduce road noise i.e. the noise created by the friction of the tyres with the road.
There is unique feature of this material by Superlon such that it helps to contain the sound produced by the speakers to reduce energy loss. This helps to enhance the bass of the sound and reduce the need to tune up the sound level on the headunit.
This concept can be applied to the following parts of the car:
1) 4 doors to reduce exterior noise e.g. motorbike exhaust noise.
2) Steering wheel column and front floor to reduce exterior noise e.g. engine noise and front undercarriage noise.
3) Wheel arches to reduce road noise i.e. the noise created by the friction of the tyres with the road.
There is unique feature of this material by Superlon such that it helps to contain the sound produced by the speakers to reduce energy loss. This helps to enhance the bass of the sound and reduce the need to tune up the sound level on the headunit.
What is Soundproofing?!
From what Wiki suggests,
Soundproofing is any means of reducing the intensity of sound with respect to a specified source and receptor. There are several basic approaches to reducing sound: increasing the distance between source and receiver, using noise barriers to block or absorb the energy of the sound waves, using damping structures such as sound baffles, or using active antinoise sound generators.
*underlined keywords will be explained in further posts
Soundproofing affects sound in two different ways: noise reduction and noise absorption. Noise reduction simply blocks the passage of sound waves through the use of distance and intervening objects in the sound path. Noise absorption, on the other hand, operates by transforming the sound wave. Noise absorption involves suppressing echoes, reverberation, resonance and reflection. The damping characteristics of the materials it is made out of are important in noise absorption.
Friday, April 20, 2007
New hobby & past time
After realising the uniqueness of this product, I decided to 'experiment' on my friends' cars for a start. Ranging from Lancers to Lancers, how boring can it get, and all I get back was a cup of coffee and hours of chatting at the kopitiam nearby. After a while, I was thinking, why not start out as a small biz venture? This can help me generate some allowance for myself (since I was still schooling and my own car is sucking up most of my allowance). And that was when I posted my first advertisement (see below) online in most of the forums I got to know.
"I'm doing soundproofing on a freelance basis, charges as follows:
Bonnet - S$60
Full Floorplan - S$250
Roof - S$150-S$180
Front fenders & wheel arches - S$60
Rear fenders & wheel arches - S$80
Doors - S$50/door"
That was about a year ago prices. Prices have since fluctuated a lot due to prices fluctuation on supplier side, however I'm proud to say I've never raised the prices, only pushed the prices down. And the most recent prices are as follows:
"Bonnet - S$50
Steering wheel column - S$50
Front floorplan - S$100
Floorplan - S$250 (sedan/hatchback)
Floorplan - S$300 (MPV/SUV)
Roof - S$150 (sedan/hatchback)
Roof - S$180 (MPV/SUV)
Front fenders & wheel arches - S$80 (>2000cc)
Front fenders & wheel arches - S$60 (<1600cc)
Doors - S$50/door
Boot lid - S$20 (do not apply to hatchbacks)
Boot spare tyre area - S$130 (<1600cc)
Boot spare tyre area - S$150 (>2000cc)"
"I'm doing soundproofing on a freelance basis, charges as follows:
Bonnet - S$60
Full Floorplan - S$250
Roof - S$150-S$180
Front fenders & wheel arches - S$60
Rear fenders & wheel arches - S$80
Doors - S$50/door"
That was about a year ago prices. Prices have since fluctuated a lot due to prices fluctuation on supplier side, however I'm proud to say I've never raised the prices, only pushed the prices down. And the most recent prices are as follows:
"Bonnet - S$50
Steering wheel column - S$50
Front floorplan - S$100
Floorplan - S$250 (sedan/hatchback)
Floorplan - S$300 (MPV/SUV)
Roof - S$150 (sedan/hatchback)
Roof - S$180 (MPV/SUV)
Front fenders & wheel arches - S$80 (>2000cc)
Front fenders & wheel arches - S$60 (<1600cc)
Doors - S$50/door
Boot lid - S$20 (do not apply to hatchbacks)
Boot spare tyre area - S$130 (<1600cc)
Boot spare tyre area - S$150 (>2000cc)"
Wednesday, April 18, 2007
New discovery
Soon after, my FYP (final year project) in school required me to do a project based on noise cancelling concepts. That was when I did a lot of research on soundproofing, sound cancelling products. And then I came across a product line from Superlon from Malaysia.
A brief outline of the material is as follows:
| SEP 180 | EPDM |
Density : 0.18±0.03 g/cm³ | |
Tensile Strength : 8 kg/cm² | |
Elongation at Break : 168% | |
Hardness (c type) : 20±3 HS | |
Heat Shrinkage : 4% | |
Compression Strength : 35±10 kg/100cm³ | |
Compression Set : 25% | |
Water Absorption : 0.005 g/cm³ | |
Thickness : 1mm - 40mm | |
Std. Size : 1m x 2m |
I experimented with the material in my project and found that it works best when used to isolate noise. E.g. a 2.5kVA disel generator produces 95dB at 1m. A 5-sided corrugated board box is created and lined with 2 layers of the 3/8" material (thickness at almost 20mm). This box was made to cover the entire generator with the sides sealed to test the capability of isolation by the material. The sound level dropped to a low of 70dB at 1m radius
A sound level meter like shown in the picture below is used.
Details of the sound level meter used can be found here.
Click here to find out more about decibels.
"DIY" experimental phase
It started off one day a year ago(18 Feb 2006), when I came across a posting on one of the internet forums which shares methods on 'DIY-ing' soundproofing of automobiles. Being curious, and troubled by my noise Mitsubishi Lancer CS3, I decided to try out myself, risking breaking parts of a S$70grand machine. I ordered a roll of OEM bitumen sheet from this "Maverick73" from NEC (Nissan Enthusiasts Club). He was rather helpful and provided some pointers about DIY soundproofing.
I 'chucked' aside the roll of material for almost a month before I could really find time to start the DIY. After almost 3 full days of tearing apart my precious ride, cutting and pasting of materials, and half time the time spent on trying to figure out the method to fix the parts back to its original place without breaking any parts, my car was fully soundproofed.
Drove out to test the car on the effectiveness of the soundproof, pretty good for a starter as most of the road noise and vibrations were gone. However, one month passed and I felt the pain, the pain of having to pay higher petrol bills. The soundproof material is way too heavy for a 1600cc 'CMI' CVT to drive. The FC (fuel consumption) increase came up to almost 13%. I used to clock about 12.8km/l on my 17" rims, after the soundproof, my FC dropped to a low 11.2. That's almost a S$30 increase of petrol bill per month, S$360 extra per year.
I 'chucked' aside the roll of material for almost a month before I could really find time to start the DIY. After almost 3 full days of tearing apart my precious ride, cutting and pasting of materials, and half time the time spent on trying to figure out the method to fix the parts back to its original place without breaking any parts, my car was fully soundproofed.
Drove out to test the car on the effectiveness of the soundproof, pretty good for a starter as most of the road noise and vibrations were gone. However, one month passed and I felt the pain, the pain of having to pay higher petrol bills. The soundproof material is way too heavy for a 1600cc 'CMI' CVT to drive. The FC (fuel consumption) increase came up to almost 13%. I used to clock about 12.8km/l on my 17" rims, after the soundproof, my FC dropped to a low 11.2. That's almost a S$30 increase of petrol bill per month, S$360 extra per year.
Introduction
In case you're wondering who I am, and why did I lead you to my blog, I'm going to elaborate my background in this virgin post.
I'm a 27 year old working professional who is very 'into' automotive noise suppresion related fields and has a lot of free time immersing myself into gaining and spreading of this specific knowledge. I'm born a very 'DIY' person, one who loves to try out own methods to resolve problems.
I'm a 27 year old working professional who is very 'into' automotive noise suppresion related fields and has a lot of free time immersing myself into gaining and spreading of this specific knowledge. I'm born a very 'DIY' person, one who loves to try out own methods to resolve problems.
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