Technical Specifications
The default settings used by the ER-200 for calculation of noise dose are
consistent with ANSI S1.25–1991 (R2002) Specification for Personal Noise
Dosimeters.
Calibration Accuracy: ±2 dB
Dose Calculation Criteria:
Exchange Rate: 3 dB
Criterion Level: 85 dB
Threshold Level: 75 dB
Criterion Time: 8 hours
Frequency Weighting: A
Response: Slow
Temperature Range of Operation: -10°C to 45°C (14°F to 113°F)
Omni-directional Microphone: Flat from 100 Hz to 15 kHz
Earphone Monitor Jack (2.5 mm): 10 mV (-40 dB re 1V)
corresponds to 94 dB SPL ±1 dB at 1 kHz
Frequency Weighting For Earphone Monitoring: Same as
microphone (A)
Power Supply: Three AAAA batteries
RMS Detector: Dynamic range 60 dB (70 to 130 dB)
Battery Life: > 250 hours continuous use
The
Importance of Monitoring Noise Exposure
Hearing loss from exposure to loud sound affects millions of people. Noise-induced
hearing loss is preventable, but most people do not know how long they can listen
to loud sound without risking hearing damage. A single noise exposure may not
result in hearing loss, but permanent damage to the inner ear from noise adds up
over time. The accumulation of too much noise day by day, year after year, is
the determining factor in hearing loss risk. A sound level meter is a device that
measures noise at a particular point in time, while a dosimeter measures sound
levels for many hours and calculates the cumulative noise dose in percent.
Daily
noise dose is determined by both the intensity of the sound and the amount of
exposure time. A 100% dose means that a person has reached the maximum noise
exposure for the day, and continued exposure to loud sound could lead to
hearing loss. Ideally, hearing protection should be used before the dose
reaches 100% since dose limits are based on averages, and some ears are more
susceptible to noise damage than others. When the noise dose exceeds 50% a
person has reached half the maximum noise exposure for the day and it’s a good
idea to use hearing protection to prevent over-exposure, particularly if a 50%
dose reading is reached early in the day.
Instructions for Use
The ER-200 has two modes of operation: Normal Mode measures and displays
noise dose continuously for up to 16 hours, and Quick Check measures noise for
two minutes, then calculates and displays the estimated dose per hour.
In Normal Mode, the dosimeter provides an early warning that the user is
approaching over exposure and should use hearing protection. Quick Check
provides a quick and easy way to measure a specific noise source to determine
if permissible exposure levels will be exceeded (e.g., loud equipment, vehicles,
power tools, music concerts or sporting events).
Reading the Display
What
the LEDs Mean
The
dosimeter uses color-coded LEDs to display noise dose in percent.
 |
| Green (Safe): Noise dose is below 100%
|
 |
| Yellow (Borderline): Noise dose is greater than 100% and less than 200%
|
|
|
| Red (High Risk): Noise dose is greater than 200%
|
|
Rate
A
slow flashing LED at 25% means that the noise dose is at or below 25%
(i.e., between 0% and 25%). When the noise dose reaches 25%, the 25%
LED flashes rapidly indicating that it is between 25% and 50%.
Similarly, when the dose exceeds 50% but is less than 100%, the 50% LED
flashes rapidly, etc.
What
Dose % Means
Simply stated, noise dose is a measurement of noise exposure. It is the
combination of the amount of sound and the amount of exposure time. Think of
100% as the limit of safe exposure, 200% as two times the permissible exposure
limit, 400% as four times the limit, etc. The risk of hearing impairment grows
with increasing noise dose. In some susceptible persons, a 100% dose indicates
enough noise exposure to cause a small amount of hearing loss over time.
| LED |
Dose % |
Risk Factor |
| green (slow flash) |
< 25% |
No risk of hearing loss |
| green (fast flash) |
25% |
No risk of hearing loss |
| green |
50% |
1/2 daily dose reached |
| yellow |
100% |
Limit of permissible exposure |
| red |
200% |
2x allowable daily dose |
| red |
400% |
4x allowable daily dose |
| red |
1600% |
16x allowable daily dose |
| red |
3200% |
32x allowable daily dose |
| Note: Use the foam windscreen when measurements are made outdoors. Do
not blow into the microphone opening because incorrect noise dose readings will
result.
|
Normal
Mode
(Daily Dose) Test Time: Up to 16 hours
Power
ON:
-
Press and release the power button. The red 3200% LED is steady,
followed by one
LED sweep.
-
The previously measured dose displays for about 10 seconds while the red 3200%
LED remains steady.
-
If the previous dose was 3200%, the red 3200% LED flashes.
-
When the red 3200% LED turns off, a slow flashing of the green 25% LED begins,
indicating the start of the measurement.
-
The dosimeter continuously displays the current dose, indicated by a flashing
LED.
-
After 16 hours, the accumulated dose is displayed for about 8 minutes.
-
During the display period, the red 3200% LED is steady and the flashing
LED indicates the dose. In cases where the accumulated dose is 3200%, the red
3200% LED flashes.
-
At the end of 8 minutes, the dosimeter automatically shuts off.
-
The dose is stored in memory and is displayed when the device is powered on
again.
Power
OFF:
-
To power off the dosimeter prior to its automatic shutdown: Press and hold
the power button until a pair of lights flashes (about 3 seconds) then release
the button.
-
Wait 5 seconds before powering ON again.
Quick
Check
(Estimated Hourly Dose) Test Time: 2 minutes
| Note: Use the foam windscreen when measurements are made outdoors. Do
not blow into the microphone opening because incorrect noise dose readings will
result.
|
Power
ON:
-
Press and hold the power button for 5 seconds. The red 3200% LED is
steady, followed by several
LED sweeps. Release power button.
-
The previously measured dose is displayed for about 10 seconds while the red
3200% LED remains steady.
-
When the red 3200% LED turns off and the green 25% LED flashes, the two-minute
Quick Check starts.
-
After 2 minutes, the steady red 3200% LED indicates the test is over.
-
The flashing LED indicates the estimated dose per hour.
-
During the display period, the red 3200% LED remains steady, unless the
estimated dose is 3200%, then the red 3200% LED flashes.
-
The estimated dose per hour
displays for 1 minute, then the dosimeter shuts off.
-
The dose is stored in memory and is displayed when the device is powered on
again.
Power
OFF:
-
To power off the dosimeter prior to its automatic shutdown: Press and hold
the power button until a pair of lights flashes (about 3 seconds) then release
the button.
-
Wait 5 seconds before powering ON again.
Windscreen
For
accurate measurements, the 35 mm (1.4") windscreen included with the
ER-200 should be used when noise is measured outdoors or near any
turbulence, e.g., from a fan. The foam windscreen allows accurate
measurement in winds up to 15 to 20 mph. Note: Blowing across the
microphone opening on the dosimeter can cause the same turbulence as a
50 mph wind.
