Re: [ST] earplugs

["Mike Bostock" <mike@xxxxxxxxxxxxxx>]

In your message regarding [ST] earplugs dated Sun, 03 Nov 2002 09:24:06 -0800,
Marc Danziger said that ...


<snipped>
>MD-  I need to get a package together for her staff by 12/15, and can use some
>MD-  help. Am particularly interested in any concrete information on the effect
>MD-  of earplugs on hearing loss, and on operator alertness and awareness.

<snipped>

Interestingly the last reference shows that riders with NO helmet have the
poorest sound detection level at any speed above 0mph!



Infotrieve MEDLINE: http://www4.infotrieve.com/newmedline/search.asp

Search Query: Hearing Loss, Noise-Induced Motorcycle

http://www4.infotrieve.com/newmedline/summary.asp?presearch=1&term=Hearing+Loss%2
C+Noise%2DInduced+Motorcycle

and

Search Query: Motorcyclists and wind noise

http://www4.infotrieve.com/newmedline/summary.asp?presearch=1&term=Motorcyclists+
and+wind+noise





In particular

Title: Motorcyclists and wind noise. Author: McCombe A  , Binnington J  ,
Donovan D  , McCombe TS  Source: Lancet, 340(8824): 911-2 1992 

No Abstract

Title: Hearing loss and motorcyclists. Author: McCombe AW  , Binnington J  ,
Davis A  , Spencer H  Source: J Laryngol Otol, 109(7): 599-604 1995 
		
Abstract: Motorcyclists are known to be exposed to excessive wind noise levels
when riding. The potential adverse effects of this exposure on their hearing
was investigated. Temporary threshold shift (TTS) was assessed by asking 18
riders to undertake a standard test run of one hour at a steady 80 mph, and
performing audiometry before and immediately afterwards. Permanent threshold
shift (PTS) was assessed by performing pure-tone audiograms on a highly
screened group of 246 motorcyclists and comparing their hearing thresholds with
those of an appropriate control group obtained from the MRC National Study of
Hearing. Significant TTS was found at 0.25, 0.5, 1 and 2 kHz. The greatest TTS
occurred at 1 kHz, with a mean hearing loss of 10.3 dB. The hearing thresholds
of the motorcyclists were significantly worse than the controls at 0.25, 0.5, 1
and 2 kHz, and was most marked at 0.5 and 1 kHz where their hearing loss (PTS)
was, respectively, 3.7 and 3.6 dB greater than expected. These findings
demonstrate evidence of both temporary and permanent hearing loss from
motorcycling and present a strong argument for the need for some form of
remedial action. 


Title: Warning signal detection and the acoustic environment of the
motorcyclist. Binnington JD , McCombe AW  , Harris M   Source: Br J Audiol,
27(6): 415-22 1993 

Abstract: A two-part study was undertaken to investigate warning signal
detection by motorcyclists. First the acoustic environment was established for
both the helmeted and bareheaded rider between speeds of 0 and 100 mph. For the
helmeted rider it was found that below 20 mph vehicle noise was dominant and
between 20 and 40 mph there was a variable contribution from both vehicle and
wind noise. At 40 mph wind noise became the dominant sound source and increased
linearly with the log10 of speed from 90 dB(A) to reach 112 dB(A) at 100 mph.
Sound levels were consistently 18 dB(A) greater for the bareheaded rider once
above 10 mph, and followed a similar pattern. Recordings of these sounds were
sampled into an Amiga computer. Suitable sound combinations were played back at
levels appropriate to speed to recreate the rider's acoustic environment at
differing speeds. The minimum detection level (MDL) of four traffic warning
signals was then measured in 19 normal hearing subjects for three test
conditions: no helmet, helmet and helmet with earplugs. The MDL for all warning
signals was lowest with a crash helmet in place for sound levels equivalent to
speeds of 30 mph or less. The addition of earplugs led to significant
reductions in MDLs at sound levels equivalent to speeds of 40 mph, or greater.
Signal detection was poorest at all speeds greater than 0 mph, when bareheaded.
We would conclude that earplugs are not required for motorcyclists in the urban
environment.(ABSTRACT TRUNCATED AT 250 WORDS) 

- -- 
Mike Bostock
http://www.toothfairy.co.uk/
Wales & SW ST Riders
http://www.sprint-st.org/

'99 Red ST

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