Hi Vicki,
I just noticed that I only used the lower limit of your figures (-15 dB) fo=
r my calculation. So, taking the upper limit of 0 dBFS would indeed result =
in 136 dB at 1.0 m.
Regards,
Raimund
--- In vickipowys <> wrote:
>
> Thanks for that Raimund.
>
> I was thinking the bikes might be even louder at 1.0m, than your
> suggested 121 dB. The car horn measured with Digital Sound Level
> Meter at 1.0m was 99.5 dB. The car horn was MUCH quieter than the
> bikes at 100 m.
>
> Wiki answers (see earlier email) suggested the Honda bike could be
> 114 dB at 100 metres.
>
>
>
> Vicki
>
>
>
> On 02/10/2012, at 7:23 PM, Raimund wrote:
>
> > Hi Vicky,
> >
> > Based on your measurements, the sound level of the bikes would be
> > approximately 74dB - 15dB + 23dB =3D 82 dB at that distance. Under
> > ideal conditions, the sound level drops by 6 dB on each doubling of =
> > the distance. This would result in the following sound levels at
> > closer distances:
> >
> > at 100 m : 82 dB
> > at 50 m: 88 dB
> > at 25 m: 94 dB
> > at 12.5 m : 100 dB
> > at 6.2 m : 106 dB
> > at 3.1 m : 112 dB
> > at 1.5 m : 118 dB
> > at 1.0 m : about 121 dB SPL
> >
> > The sound propagation over larger distances near the ground is
> > however quite complex (depending on vegetation, temperature of both =
> > the ground and the air, wind speed, wind direction, =85). So, the
> > estimated sound level of 121 dB SPL at 1 m is just a very rough
> > estimate.
> >
> > I guess that the number of 130 dB that you found for that bike
> > model applies to a distance of 1 meter, which seems to match your
> > own measurements quite well.
> >
> > Regards,
> > Raimund
> >
> >
> > --- In vickipowys
> > <vickipowys@> wrote:
> >>
> >> Hi Mike,
> >>
> >> I sent the following email to Eric Benjamin, and hoping you might be
> >> able to help out with the figures I have now given? i.e. how would
> >> they translate into dB for noise regulation purposes?
> >>
> >> (I am feeling somewhat shell-shocked today after the past 10 days of
> >> these bikes riding in circles, 2-strokes and 4-strokes and various
> >> old cars as well. :-(
> >>
> >> best wishes,
> >>
> >> Vicki
> >>
> >>
> >> Hi Eric,
> >>
> >> Thanks very much for your response. It is very hard to find the
> >> specific information I want re noise and dB, but my legal angle so
> >> far is that excessive noise from neighbours is definitely regarded as
> >> a legal nuisance. I reckon I can support my case by claiming that
> >> the bikes in question are motocross bikes (Honda CR85) designed for
> >> racing and unable to ever be registered because the noise is way
> >> above the registerable vehicle limit (which is Australia seems to be
> >> 95-100 max). I only found 1 reference (Wiki Answers) to the CR85
> >> having output of 130 dB, altho I think it is probably true. It would
> >> be good if I could actually demonstrate how noisy the bikes are.
> >>
> >> Today (now that the bikes have gone home) I received my Digital Sound
> >> Level Meter. With it, I checked my car horn at 100 metres in still
> >> conditions at max. 74.6 dB. The same horn recorded at 100 metres
> >> measures -23 dB on my LS10 (low sensitivity, vol. 10, no low cut).
> >>
> >> In comparison, the racing bikes at a distance of 100 metres, as
> >> recorded on LS10 same settings, is from -15 dB to 0 dB.
> >>
> >> Quieter 4-stroke bikes at 100 metres seem to be about -22 dB on LS10.
> >>
> >> (I am measuring the dB via Izotope RX, rather than on the recorder
> >> itself).
> >>
> >> I am hopeless at maths and in understanding how dB works, and I was
> >> rather hoping you might be able to tell me what dB you think the
> >> noisy bikes might be, as might be measured on a sound level meter?
> >>
> >> I'd be very grateful if you could help out Eric,
> >
> >
> >
> > ------------------------------------
> >
> > "While a picture is worth a thousand words, a
> > sound is worth a thousand pictures." R. Murray Schafer via Bernie
> > Krause.
> >
> > Yahoo! Groups Links
> >
> >
> >
>
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