The Rural Voice, 1985-11, Page 50NOVEMBER
SPECIAL
HEAVY DUTY
SNOWBLOWER
DAVE HOLLIDAY LTD. r
2 mi N. Mount Forest
519-323-1340 kIONN Map
LIQUID
MANURE
PUMPS
Exclusive Multi -
Direction Agitator
permits vertical
mixing of layers
in pit.
BUY DIRECT & SAVE
Also all sizes of PTO
tractor and electric
pumps.
See our new
economy model.
(SINCE 1902)
R.R. 1, Sebringville
(Wartburg)
519-393-6284
Check the noise levels
of your machines
Prolonged exposure to high intensi-
ty noise can cause hearing impair-
ment, fatigue, and stress. Anyone
working in a noisy environment for a
considerable length of time is more
apt to make mistakes than if working
in a quiet environment.
Noise level is measured in units
called decibels (dB). Since the human
ear responds differently to different
noise frequencies, the decibel unit has
been slightly modified and is called
dBA, which is decibels measured us-
ing the A -weighting network of a
sound level meter. These units have
been internationally accepted. It has
been established that prolonged ex-
posure of more than eight hours a day
to noise levels above 90 dBA can in-
duce hearing damage.
The decibel scale is not linear, but
logarithmic. Hence the sum of noise
levels from two identical sources of
80 dBA each will be 83 dBA and not
160 dBA. This means that every 3
dBA increase in noise level indicates
double the power input to a person's
ear.
Noise level during normal conver-
sation is about 60 to 65 dBA. A
household blender has a noise level of
about 80 dBA. Higher levels than this
bcome progressively more uncomfor-
table.
Noise levels can be measured by a
Table 1. Acoustic Noise Levels of Tractors at Full
Throttle, dBA
Tractor dBA Iesels for meter locations
1 2 3 4 5
T.
T.
T
T.
T•.
1-
95 97 87 100 85
94 5 95 87.5 96 88.5
94 95 89 94.5 83
102 100.5 86 100 85
92.5 94 85 94.5 81.5
88 93 82 94 81.5
97 97 90 97.5 87
Table 2. Acoustic Noise Levels of Combines at Full
Throttle with Threshing Unit in Operation.
dBA
Combine dBA Iesels for meter locations
1 2 3 4 5
c:
c:
C.
C,
87
94 5
90
89.5
92
98
95
92 5
92
87
88
84
92
90
89
87.5
77
91
89.5
97.5
91
PG H. SP1 ' •I AAI EQUIPMENT SECTION, NOVEMBER, 1985
battery-operated portable instrument
called a Sound Level Meter.
A noise level sampling was made
on some late -model, large tractors
and combines manufactured by ma-
jor, reputable companies serving On-
tario. The sound level readings were
taken at four places outside the cab
and at the approximate location of
the operator's head inside the cab.
The results are tabulated in Tables 1
and 2. The sound level meter loca-
tions were:
• about 1 metre (m) in front of the
machine,
• about 1 m from the right side of the
machine,
• about 1 m behind the machine,
• about 1 m from the left side of the
machine,
• inside the driver's cabin at the
operator's ear level.
In Table 2 the noise levels in the
cabs varied from 77 to 97 dBA and,
of course, the levels were higher im-
mediately outside the cab of most
machines.
All combines and tracIors were new
and probably as they become older,
cracks will develop in the cab seals,
and the machines will register higher
noise levels in the cab.
Workers in the U.S. are protected
by federal law (the Walsh -Healey
Public Contracts Act) from exposure
to more than the maximum allowable
levels and times as shown in Table 3.
If noise in your tractor or combine
registers 92 dBA in the cab, then
operating it for more than six hours a
day will likely result in hearing im-
pairment. This would involve Toss of
ability to discern the higher sound
frequencies, and it occurs so gradual-
ly and insidiously that the victim is
unaware of the loss until it becomes
severe. Where exposures for longer
periods cannot be avoided, ear pro-
tection should be used.
For your own health and safety:
• ask your dealer for the decibel
reading in the cab of the machine you
wish to buy,
• intermittently (perhaps annually)
have the noise levels of your machines
checked and, if necessary, wear ear
protectors or have the cab recaulked.
W.K. Bilanski
S.R. Ghate
University of Guelph