I was talking about this at the recent northern meet and thought I'd look into it a little bit more and just provide some information/advise for people.
I'm an acoustic engineer by trade and currently 90% of the way through a diploma in acoustics, so have a rough basis of knowledge in a very complex subject. excuse me if I waffle on as it will be a bit of an essay, ive tried to stick to the main points only, some of you may find this interesting and after all, you only get one set of ears.
The quicksilver Super Sports is rated at 98dB at approx 6k rpm. Now this information is pretty much useless. They have provided a single figure which doesn’t tell you much, i.e. where that 98dB exists, or what frequencies contribute to it. Sound is usually measured across a spectrum covering low, medium and high frequencies. And just a simple 98dB doesn’t tell you what frequencies attribute to this level, whether that’s in the car, at the exhaust pipes, a metre from the exhaust pipes, if at ear height behind the car, or at floor level etc. Id imagine its measured at 1 metre from exit point, 1.5 metres above the ground to avoid reflections...but it could be right at the tailpipes.
But one thing's for sure, its bloody loud!!!
98dB is relating to the pressure or the power of the sound within air (the manufacturer doesnt confirm which, i assume it's pressure). We as humans do not hear this in such a manner and there's a correction that you need to apply to it to make the figure appear inline with human response this is called 'A-Weighting' and signaled by an (A) - i.e. 98dB(A) .
Now I can't see anywhere which details that quicksilver quoted in dB(A), although this information should be available, it isn't. The A weighting correction at the lower frequencies (where the exhaust boom exists) is a reduction so what we hear would be 98dB(A) or lower.
The standard exhaust is quoted at 81dB. Now whilst both measurements are useless without taking the measurements to the proper standards…it does give you an idea of the difference.
Decibels (db) are measured on a logrhythmic scale. for example 98dB is double the volume, or twice as loud at 95dB. for each 10dB, the volume level increases by 10 times. ie 90dB is 10 times louder than 80dB.
98 dB is 17dB louder than the standard exhaust of 81dB, which means the super sports theorectically produces the equivalent noise of approximately 50 standard exhausts. (81+10log50 - for the maths geeks)
Louder sounds cause damage in a short period of time. Estimation of a safe duration of exposure is possible using an exchange rate of 3 dB. As 3 dB represents a doubling of intensity of sound, duration of exposure must be cut in half to maintain the same energy dose.
For example, the "safe" daily exposure amount at 85 dB(A) is 8 hours, while the "safe" exposure at 91 dB(A) is only 2 hours. Also, not everyone is the same and for some people, sound may be damaging at even lower levels than 85 dB(A).
Therefore the crux of the whole point,
Standard exhaust: 81dB - Below maximum daily exposure level - no time limit needed.
Quicksilver Sports: 91dB - Max dose 2Hrs in one day.
Quicksilver Supersports: 98dB, is limited to approx 30 mins exposure in one day.
This is a very rough approximation due to the quality of the information available, however, if you overstep these durations you may risk hearing damage.
In order to get actual values, id need to conduct an experiment to British standards and basically have a sound pressure level meter in the cabin where the ear would be and take an overall dB(A) reading. My fear is that the reverberant/resonant field within the cabin will be louder than the levels measured outside the car. The sound will get trapped within the car and reflect all over the place to give an impression of increased volume.
This may actually be worse inside the cabin at 2-3k rpm than it would be at 6k rpm, the lower the engine speed, the lower the frequency of the sound is produced (i.e. diesel bus at idle vs formula one car at 18k rpm).
High frequency noise is easy to control, low frequency is not. for example high frequency could be blocked with a sheet of paper, low frequency can go straight through concrete.
Sound levels increase with proximity; as the source is brought closer to the ear, the sound level increases. This is why music is more likely to cause damage at the same output when listened to through headphones, as the headphones are in closer proximity to the ear drum than a loudspeaker. With the invention of in-ear headphones, these dangers are increased. Also bear in mind that hearing damage is hereditary!
The solutions:
1. The principle of all noise control is to reduce noise at the source. which would mean, change the exhaust…which although good advise is not what owners would wish.
2. reduce your exposure. simple enough…don’t drive for longer periods of time a day. fine, until you want to drive somewhere of reasonable distance and not a practicle option
3. Noise control at the receiver (your ear),
rays bulkhead design appears to be very successful, no recorded data, but i would imagine a 5,10dB+ reduction is feasble it may even be higher. My only comment in terms of acoustics would be the bulkhead is only as good as the installation. Any air gaps will completely undermine its performance.
Another option is ear plugs…which again are only effective if used correctly and worn in the correct manor, good ones are expensive…..but and here's the good bit, WILL make the difference. You can get earplugs to reduce 35dB+ which is way more than needed and would save your hearing.
Hearing deteriorates with age naturally, the last thing you want to do is speed it up. When you damage your hearing you loose the ability to to differentiate between consonants and vowels and conversation becomes harder. hearing aids, despite technology, are no replacement for a good set of ears & can be as bad as they are good.
remember kids, damage to your ears is irreversible!!
I'm an acoustic engineer by trade and currently 90% of the way through a diploma in acoustics, so have a rough basis of knowledge in a very complex subject. excuse me if I waffle on as it will be a bit of an essay, ive tried to stick to the main points only, some of you may find this interesting and after all, you only get one set of ears.
The quicksilver Super Sports is rated at 98dB at approx 6k rpm. Now this information is pretty much useless. They have provided a single figure which doesn’t tell you much, i.e. where that 98dB exists, or what frequencies contribute to it. Sound is usually measured across a spectrum covering low, medium and high frequencies. And just a simple 98dB doesn’t tell you what frequencies attribute to this level, whether that’s in the car, at the exhaust pipes, a metre from the exhaust pipes, if at ear height behind the car, or at floor level etc. Id imagine its measured at 1 metre from exit point, 1.5 metres above the ground to avoid reflections...but it could be right at the tailpipes.
But one thing's for sure, its bloody loud!!!
98dB is relating to the pressure or the power of the sound within air (the manufacturer doesnt confirm which, i assume it's pressure). We as humans do not hear this in such a manner and there's a correction that you need to apply to it to make the figure appear inline with human response this is called 'A-Weighting' and signaled by an (A) - i.e. 98dB(A) .
Now I can't see anywhere which details that quicksilver quoted in dB(A), although this information should be available, it isn't. The A weighting correction at the lower frequencies (where the exhaust boom exists) is a reduction so what we hear would be 98dB(A) or lower.
The standard exhaust is quoted at 81dB. Now whilst both measurements are useless without taking the measurements to the proper standards…it does give you an idea of the difference.
Decibels (db) are measured on a logrhythmic scale. for example 98dB is double the volume, or twice as loud at 95dB. for each 10dB, the volume level increases by 10 times. ie 90dB is 10 times louder than 80dB.
98 dB is 17dB louder than the standard exhaust of 81dB, which means the super sports theorectically produces the equivalent noise of approximately 50 standard exhausts. (81+10log50 - for the maths geeks)
Louder sounds cause damage in a short period of time. Estimation of a safe duration of exposure is possible using an exchange rate of 3 dB. As 3 dB represents a doubling of intensity of sound, duration of exposure must be cut in half to maintain the same energy dose.
For example, the "safe" daily exposure amount at 85 dB(A) is 8 hours, while the "safe" exposure at 91 dB(A) is only 2 hours. Also, not everyone is the same and for some people, sound may be damaging at even lower levels than 85 dB(A).
Therefore the crux of the whole point,
Standard exhaust: 81dB - Below maximum daily exposure level - no time limit needed.
Quicksilver Sports: 91dB - Max dose 2Hrs in one day.
Quicksilver Supersports: 98dB, is limited to approx 30 mins exposure in one day.
This is a very rough approximation due to the quality of the information available, however, if you overstep these durations you may risk hearing damage.
In order to get actual values, id need to conduct an experiment to British standards and basically have a sound pressure level meter in the cabin where the ear would be and take an overall dB(A) reading. My fear is that the reverberant/resonant field within the cabin will be louder than the levels measured outside the car. The sound will get trapped within the car and reflect all over the place to give an impression of increased volume.
This may actually be worse inside the cabin at 2-3k rpm than it would be at 6k rpm, the lower the engine speed, the lower the frequency of the sound is produced (i.e. diesel bus at idle vs formula one car at 18k rpm).
High frequency noise is easy to control, low frequency is not. for example high frequency could be blocked with a sheet of paper, low frequency can go straight through concrete.
Sound levels increase with proximity; as the source is brought closer to the ear, the sound level increases. This is why music is more likely to cause damage at the same output when listened to through headphones, as the headphones are in closer proximity to the ear drum than a loudspeaker. With the invention of in-ear headphones, these dangers are increased. Also bear in mind that hearing damage is hereditary!
The solutions:
1. The principle of all noise control is to reduce noise at the source. which would mean, change the exhaust…which although good advise is not what owners would wish.
2. reduce your exposure. simple enough…don’t drive for longer periods of time a day. fine, until you want to drive somewhere of reasonable distance and not a practicle option
3. Noise control at the receiver (your ear),
rays bulkhead design appears to be very successful, no recorded data, but i would imagine a 5,10dB+ reduction is feasble it may even be higher. My only comment in terms of acoustics would be the bulkhead is only as good as the installation. Any air gaps will completely undermine its performance.
Another option is ear plugs…which again are only effective if used correctly and worn in the correct manor, good ones are expensive…..but and here's the good bit, WILL make the difference. You can get earplugs to reduce 35dB+ which is way more than needed and would save your hearing.
Hearing deteriorates with age naturally, the last thing you want to do is speed it up. When you damage your hearing you loose the ability to to differentiate between consonants and vowels and conversation becomes harder. hearing aids, despite technology, are no replacement for a good set of ears & can be as bad as they are good.
remember kids, damage to your ears is irreversible!!
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