Introduction
The MA 39 from Maico Diagnostics is
part of a series of portable screening audiometers that allows you to choose
which has the features that best meet your needs. The MA 39, for example,
provides basic air conduction. Conduct a testing battery including pure
tone screening and air threshold.
Product
Overview and Description
The Model MA 39 is a precision instrument designed to permit simple, rapid
and reliable hearing tests. Their application ranges from school testing
programs, pre-employment examinations and monitoring audiometry for hearing
conservation programs. The instrument provides all of the pure tone frequencies
and full dynamic range specified by the American National Standards Institute
S3.6 1996.
Features include, a full
range electronic attenuator (-10 dBHL to 110 dBHL mid frequencies), with
all input/output switching and routing performed electronically. Large
LED* numeric displays show the selected frequency and HL intensity. Small
individual LED's are used to show the selected function (See Figure 1).
The model MA 39 retains the side mounted controls for frequency and HL
setting as well as the dual present/interrupt buttons so familiar to Maico
audiometer users. All functions, actuators/push button controls, provide
a tactile feedback to the operator whenever a function is selected or
operated. In addition a bright LED indicator is associated with the selected
function.
Maico audiometers have
been designed to meet the most rigorous of electrical safety standards
and to provide years of reliable operation with a rugged durability that
has become the trademark of Maico portable audiometers.
Product
Use and Procedures
Set
Up
Place the MA 39 on a stable counter or table. Open the side latches and
fold the lid back. Fold the lid back one more time to reveal the accessories
that are packaged within the rear storage compartment. If you haven't
already done so, unpack and inspect the accessories.
The TDH 39 headphones
are serialized and should match the serial number on the instrument. Check
to see that the numbers match, as this will confirm that the headphones
and MA 39 were calibrated together. The optional insert phones do not
have a serial number, but if they were ordered at the same time as the
MA 39 they were calibrated to that particular instrument and should not
be used on another without recalibration.
Turn the MA 39 around
so that you can view the rear jacks. Insert the RED (right) plug of the
TDH 39 headset into the right air conduction earphone jack labeled R,
under AC (Air Conduction). Insert the BLUE (left) plug into the left AC
earphone jack labeled L.
The insert phones are
installed in the same manner. Insert the RED (right) plug of the insert
phone cord into the insert phone jack labeled R, under INS (INSert phones).
The BLUE (left) plug is inserted into the jack labeled L.
Patient Response Switch
- Optional - Locate the PATIENT RESPONSE jack on the rear panel and insert
the plug end of the switch.
Sound Room Patch Cords
- Optional - When using the MA 39 in a sound room, connect the patch cords
from the sound room to the proper right and left earphone/insert phone
jacks, patient response jack.
Air Conduction Testing
Air conduction testing is used to measure the patient's hearing threshold
levels. The test is usually started on the ear with better hearing.
| 1. |
Turn the MA 39 on
and let it warm up for 10 minutes before using. Upon power-up the
initial setting will be in audiometric testing mode, right phone,
1 KHz, 30 dB intensity. |
| 2. |
Seat the patient
so that he/she is facing away from the instrument at a 90° angle
and cannot see what the operator is doing. Give a brief description
of what the patient can expect to hear. Using a consistent explanation
will help provide more reliable results. Instructions may be expressed
as follows: "I am going to place these headphones on your ears.
You will hear a tone or beeping sound, which may be loud or soft.
Whenever you hear, or think you hear one of these tones, raise your
hand. Lower it when you no longer hear the tone. Listen carefully
because some tones are very soft." |
| 3. |
Eliminate any obstructions
that could interfere with placement of the earphone cushion on the
ear (i.e. hair, earring, eyeglasses, hearing aids, etc.). Adjust the
headband so that the earphone cushions are centered over the ears
(RED on the right ear, BLUE on the left) and the receivers line up
with the ear canals. The headband should rest firmly over the center
of the head and place firm pressure on both ears. |
| 4. |
Choose PULSE and/or
FM if you wish. Set the INTENSITY and FREQUENCY to the desired level. |
| 5. |
Press STIMULUS to
present the test tone. The STIM LED should light. If the patient hears
the tone he/she will raise their hand or press the patient response
switch, indicated by the patient response LED. |
The most commonly used
hearing threshold procedure is called a modified Hughson-Westlake procedure.
| 1. |
Start at 1000 Hz
with a level of 0 dB and present a signal for at least 1 second. If
no response, increase in 10 dB steps until the patient responds. |
| 2. |
Increase another
10 dB for a confirmation and orientation. If the patient responds
again, decrease the presentations in 10dB steps until the patient
no longer responds. |
| 3. |
Increase in 5 dB
steps until the patient responds. Once the patient responds, descend
10 dB until there is no response. Increase again in 5 dB steps. |
| 4. |
Repeat until you
have 2 out of 3 ascending responses at the same level. Change the
frequency and repeat above procedure until you have thresholds for
the number of frequencies that you wish to test. |
The hearing threshold
is defined as the lowest hearing level at which the patient responds to
two out of three ascending stimuli at the same level.
Features
and Benefits
The MA 39 comes standard with a built-in RS232 interface for PC and NOAH
compatibility. For portability, the MA 39 comes standard in a soft case
which makes the total weight only 9.9 pounds including accessories. Other
features include:
 |
quiet, reliable
electronic switches
|
|
insert phones capability
|
|
bright, easy to
read display screen
|
|
side control dials
are ergonomic for maximum comfort
|
|
hard carrying case
available
|
|
one year limited
warranty
|
Frequently
Asked Questions
| Q: |
What
is the frequency accuracy of the MA-39? |
| A: |
The frequency accuracy
is ±1% maximum of indicated frequency.
|
| Q: |
How
much does the unit weigh? |
| A: |
There are 2 cases,
in the soft case the unit is only 9.9lbs. The weight in the hard sided
carrying case is 16.5 lb/7.5 kg.
|
| Q: |
Can
the unit be used in a standard electrical outlet? |
| A: |
This Maico instrument
has been designed to meet the most exacting electrical safety requirements
for patient care equipment. The hospital grade, 117 volt alternating
current, three-prong plug (or the appropriate plug for your country)
should be inserted into a mating three-prong hospital grade receptacle
that is properly grounded. This will ensure reliable and safe operation
of this precision instrument. Injury to personnel or damage to equipment
can result when a three-prong to two-prong adapter is connected between
the power plug and an AC outlet or extension cord.
|
| Q: |
How
do I use the Pulse or FM tone function on my MA-39? |
| A: |
PULSE/FM. Enables
PULSE and/or FM stimulus.
| PULSE
LED on |
Pure
tone stimulus will be pulsed. |
| FM
LED on |
Pure tone
stimulus will warble. |
Both
PULSE and
FM LEDs on |
Pure tone
will pulse and warble. |
| Both
LEDs off |
Pure tone
stimulus only. |
|
| Q: |
How
do I prepare a person for a screening? |
| A: |
The operator should
place the person to be tested at ease concerning the test. The operator
should explain the purpose of the test and what kind of sound or sounds
will be heard. An unvarying and uniform explanation to the person
being tested will provide test results that are consistently high
in reliability. An explanation for pure tone or baseline audiometry
might be expressed as follows: "I am going to place these headphones
on your ears. You will hear a whistle or beeping sound that may be
loud or soft. Whenever you hear or think you hear one of these sounds,
raise your hand (or press the response switch button) and lower your
hand (or release the button) when you do not."
|
| Q: |
We
test in the gymnasium and it is often noisy. Will this affect our
screening results? |
| A: |
Excessive sounds
or noise in the chosen test environment can produce a masking effect
and therefore affect the test results. The selected site should be
away from conversations, noisy business equipment, hallway traffic
and other noise producing environments. The lower test frequencies
are most affected by these types of noises.
In some instances
it may be necessary to acoustically treat the test site in order
to achieve the necessary quietness for testing purposes. Commercially
available "sound rooms", which are designed to provide
an acoustically treated testing environment, are recommended where
baseline or threshold audiometry is required. These rooms are available
in a variety of sizes and isolation capabilities.
|
| Q: |
When
do I know I have reached the child's threshold? |
| A: |
You can check the
specific requirements and state guidelines with your state health
departments. Often states have different screening and threshold requirements.
As a standard, the hearing threshold is defined as the lowest hearing
level at which the patient responds to two out of three ascending
stimuli at the same level.
|
| Q: |
What
maintenance is recommended with this unit? |
| A: |
To maximize the
service life of your audiometer and accessory equipment, we suggest
the following:
| 1. |
Turn
off the instrument overnight. |
| 2. |
Wipe
the headset cords, ear cushions and casing occasionally with
a cloth dampened (not dripping wet) with warm water. Dry with
a soft cloth. |
| 3. |
Leave
the accessories such as the headset, permanently connected to
the audiometer to minimize strain on the connections. It is
not necessary to disconnect accessories not in use while performing
other tests. Should it be necessary to disconnect cords, always
grasp the barrel of the plug - never pull the cords. Never drop
or snap the headphones together. Mechanical shock may change
the earphone's electrical and operational characteristics and
require calibration of the MA 39. |
| 4. |
Close
the audiometer cover at the end of each day to minimize dust
collection. |
| 5. |
Avoid
sharply bending or twisting any of the cords. Although they
are designed to be highly flexible, rough treatment may cause
damage. Broken or defective cords can cause crackling noise
and intermittent or weak operation in the headset. Headset cords
may be replaced without re-calibrating the audiometer |
| 6. |
This
Maico audiometer has been designed to meet the most exacting
electrical safety requirements for patient care equipment. The
hospital grade 117 volt AC three prong plug should be inserted
into a mating three prong hospital grade receptacle that is
properly grounded. This will ensure reliable and safe operation
of this instrument.
The use of a three prong to two prong adapter should be avoided,
and is not recommended.
|
| 7. |
Also
a yearly calibration is recommended. See information under the
heading "other information".
|
|
| Q: |
How
do I clean my MA-39? |
| A: |
First, disconnect
the power cord before cleaning. Clean the instrument, headphones,
and other accessories with a soft cloth dampened with a little warm,
soapy water. Do not use alcohol to clean.
The ear cushions
of the headphones can be detached for cleaning. To remove, gently
pull the cushion away from the headphone. To re-assemble, press
it back onto the headphone. Make sure that the sound outlet hole
sits exactly in the middle of the earphone.
|
Technical
Specifications
| Frequency
accuracy |
±1%
maximum |
| Attenuator
linearity |
±0.5
dB per 5 dB step |
| Distortion |
0.5%
typical, 2% maximum |
| Rise/fall
time |
35
msec. typical |
| Frequency
modulation |
±5%
triangle wave modulation at 5Hz |
| Voltage
requirements |
117/234
volts AC, switchable |
| Frequency
range |
125Hz
to 8kHz |
| Hearing
level range: |
| Air
conduction |
-10
to 110 dB HL |
| Bone
conduction |
-10
to 70 dB HL |
| Narrow
band noise |
-10
to 100 dB HL |
Articles
Click
HERE
to view the sales flyer on the MA-39.
Click HERE
to review the MA-39 operation manual.
Other Information
Calibration
The
optimum length of time between calibrations for audiometers varies, depending
upon the treatment given the instrument and the headphones. It is recommended
that the instrument have a laboratory calibration at least once every
year. Since rough handling, such as dropping the headphones, can easily
cause calibration errors it is advisable to establish a biological calibration
check as soon as you receive the instrument. Should you feel at a later
date that the audiometer's calibration might be in error, perform a biological
check on a known ear. If all re-tests show major changes, calibration
is probably in error. All repair and calibration should be done at an
authorized Maico Special Instruments Distributor service center, such
as School Health Corporation. This assures the use of quality materials
by trained and experienced technicians using the proper, accurate equipment.
Additional information
can be seen on the Maico website at www.maico-diagnostics.com.
Warranty
One
year limited warranty extended to the original purchaser on the instrument,
by Maico, through the distributor from whom it was purchased. The warranty
covers defects in material and workmanship for a period of one year from
the date of delivery of the instrument to the original purchaser. Accessories
which are purchased from Maico at the same time as the instrument are
warranted for one year from the date of purchase.
Reimbursement
The MA 39 is CPT code reimbursable for the following codes:
92551 - Screening, pure tone
92552 - Threshold, air
Product Ordering Information
| SH
Catalog # |
Product
Name |
| 51082 |
Maico
MA 39 with soft case |
| 51000 |
Maico
MA 39 with hard case |
|
