Introduction
The MA 40 from Maico Diagnostics is
part of a series of portable screening audiometers that lets you choose
which has the features to best meet your needs. The MA 40, for example,
provides air conduction as well as bone conduction. Conduct a complete testing
battery including pure tone screening and air threshold as well as air and
bone conduction.
Product
Overview and Description
The MA 40 is a portable, one and a half-channel audiometer, offering pure
tone audiometric testing. It performs tests using TDH 39 headphones, a B-71
bone conduction receiver or optional insert phones. Built-in test signals
include pure tone, pulse tone, warble tone and narrow band noise. Outputs
have separate jacks for TDH 39s, optional insert phones and bone conduction.
The MA 40 offers air
conduction frequencies from 125 Hz to 8 kHz, with intensity levels from
-10 dBHL to 110 dBHL. Bone conduction test frequencies are 250 Hz to 6
kHz with intensity levels of -10 dBHL to 70 dBHL. The MA 40 has a built-in
RS 232 interface. Calibration is performed via the front panel and thus
simplifies annual service calibrations.
Product
Use and Procedures
Set
Up
Place the MA 40 on a stable counter or table. Flip 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 40 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 40, they were calibrated to that particular instrument
and should not be used on another without calibration.
Turn the MA 40 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.
Bone Conduction Transducer
- Insert the bone conduction plug into the port labeled BC (Bone Conduction).
Patient Response Switch
- Optional - Locate the PATIENT RESPONSE jack on the rear panel and
insert the plug end of the optional switch.
Sound Room Patch Cords
- Optional - When using the MA 40 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, and bone conduction jack.
Power Up - Insert
the power plug into the rear socket, then into a three-conductor electrical
outlet (or the appropriate outlet for your country).
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 40 on
and let it warm up for 10 minutes before using. Upon power up the
initial setting will be in audiometric testing mode, left ear on air
conduction, 1 kHz, 30 dB intensity, right ear on noise, 0 dB. |
| 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. |
Set the OUTPUT
SELECT to AC. 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.
Bone Conduction Testing
Bone conduction is the transmission of sound waves through the skull directly
to the inner ear. This test conveys useful information about the function
of the inner ear and whether there is neural hearing loss. Threshold differences
between air conduction and bone conduction are a good indicator of middle
ear disease or external ear canal obstruction.
| 1. |
Place the bone
conduction receiver so that the flat, circular side of the transducer
is seated on the mastoid, right on the ledge of the cranial bone behind
the auricle. The other side of the headband is placed in front of
the opposite ear. |
| 2. |
Set the OUTPUT SELECT
to BC (bone conduction). Perform the test in the same manner as for
air conduction testing. Record all measurements and results. |
Masking
To ensure that the patient does not experience crossover (sound transmitted
through bone conduction over to the opposite ear) you must mask the opposite
ear. Masking is performed with a noise signal in the headphone. A narrowband
noise is used in pure tone audiometry. The noise automatically changes
its center frequency following the frequency of the test signal.
| 1. |
The masking noise
is continuously presented for effective masking. You may interrupt
the masking signal by pressing the STIMULUS key.
|
| 2. |
To mask while performing
bone conduction tests, place the headphone on the non-test ear so
that the receiver is directly in line with the ear canal. Adjusting
the headband, place the other headphone so that it sits directly on
the cheekbone.
|
| 3. |
Adjust the masking
intensity level whenever you change the test signal level.
|
Features
and Benefits
The MA 40 comes standard with a built-in RS232 interface for PC and NOAH
compatibility. For portability, the MA 40 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 bone conduction testing? |
| A: |
Bone conduction
is the transmission of sound waves through the skull directly to the
inner ear. This test conveys useful information about the function
of the inner ear and whether there is neural hearing loss. Threshold
differences between air conduction and bone conduction are a good
indicator of middle ear disease or external ear canal obstruction.
|
| Q: |
What
accessories will come with my MA-40? |
| A: |
Standard Accessories
that are shipped inside the case of the unit are: TDH 39 headset,
B71 Bone Vibrator, Bone Cord, Bone headband, Audiogram pad and the
Operator's Manual.
|
| Q: |
What
is the frequency accuracy of the MA-40? |
| 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 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 when doing an air conduction
screening? |
| 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 40. |
| 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. |
Also
a yearly calibration is recommended. See information under the
heading "other information".
|
|
| Q: |
How
do I clean my MA-40? |
| 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-40.
Click HERE
to review the MA-40 operation manual.
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 40 is CPT code reimbursable for the following codes:
92551 - Screening, pure tone
92552 - Threshold, air
92553 - Air and bone
Other
Information
Calibration
The optimum length of time between re-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 http://www.schoolhealth.com/shop/svs_clbrt.asp
This assures the use of quality materials by trained and experienced technicians
using the proper, accurate equipment.
Additional information
can be found on Maico's website at www.maico-diagnostics.com.
Product Ordering Information
| SH
Catalog # |
Product
Name |
| 51083 |
Maico
MA 40 with soft case |
| 51001 |
Maico
MA 40 with hard carrying case |
|
