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Audiometer and Hearing Aid measurements
/ mini seminar
DELTA Technical-Audiological Laboratory - TAL
Edisonsvej 24
5000 Odense C
Tlf. 72 19 41 00 – tal@delta.dk
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Program
14:00 Welcome and introduction/ Gert Ravn
14:10 SW Development and implementation of speech-gain measurements
according IEC 60118-15/ Søren L Jørgensen
14:40 Future EMC measurements on Hearing Aids/ Allan G Kristensen
15:00 New aspects of hearing aid documentation according IEC 60601-2-66 and
updated IEC 60118-13/ Gert Ravn
15:20 Audiometer calibration. Round Robin test results/ Carsten Daugaard
16:00 Closing
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Audiometer calibration - Agenda
Background
Audiometers in Denmark
Public clinics
ENT specialists
Private dispensers
Issues in practical audiometer calibration
Questions reading the standards
Deviations in audiometer testing
Round robin test
Results
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Background
DELTA has as consultants for hearing health care in Denmark
traditionally been involved in audiometer calibration.
Before 2000 as consultants for technicians in public health care
when special questions about calibration arose
DELTA has published 2 technical reports in Danish explaining
calibration issues
For many years DELTA has been represented in WG 10
Audiometric equipment by Gert Ravn (and for a period Carsten
Daugaard)
Since 2000 DELTA has – as a part of the certification of private
clinics tested their audiometer’s calibration
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Audiometers in Denmark
Two Danish manufactures dominate the market, a small handful
other manufactures are represented.
ENT specialists, often older audiometers, calibrated by
manufactures based on a service contract
Approx. 17 public clinics, older clinical audiometers, but also state
of the art equipment. calibration is moving from in-house to
service contracts
Approx 200 Private clinics (some of them also ENT specialists),
newer audiometers – often portable, yearly calibrated by
manufactures based on a service contract and controlled by
DELTA as a part of the certification
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Issues in practical calibration:
Speech audiometry
Offset value
Practical issues in speech calibration
Free field calibration
Attenuation of background noise
RETSPL for new headphones
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Speech audiometry i Denmark
Since Dr. Røjskjær in Odense back in the fifties conducted the first
speech tests, this auditory test has been carried out in Denmark
Recorded speech material have existed also since the fifthies
Late in the eighties the national material ”Dantale” emerged and grew
to be the national standard
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Speech audiometry i Denmark II
Based upon the DANTALE material a Discrimination score (DS) and a
Speech recognition threshold (SRT) is measured.
DS corresponds to the in ISO8253-3 clause 3.12 defined ”maximum
speech recognition score”
SRT corresponds to some extend th the in ISO 8253-3 i 3.13 defined
”speech recognition threshold level”, however the threshold for the
danish one syllable digits are defined as 2 out of three (66%) where
the standard defines 50 % as the threshold
Both are as standard presented in headphones with no noise.
Thresholds should be obtained in dB HL
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Speech audiometry i Denmark III
According to the IEC 60645-2:1994 standard speech audiometry
offset are calibrated to 20 dB.
In principle every speech material have its own unique threshold, but
the 20 dB is a universal offset.
Speech audiometry are calibrated at 1 kHz and presented through
TDH-39
Preferably the headphone should have been equalised out
Clinicians switching to other headphones report misfits between
audiometry and speech audiometry findings
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ANSI- values for speech audiometry
ANSI S3.6 -1996 offers differentiated
offset values for the three transducers
Lowering the offset to 12,5 for Insert
phones (in 2CC coupler)
DELTA investigated if 12,5 dB was a
meaning full value for insert phones
on DANTALE material
Or the documented offset of 28,15 dB
from the reports of the DANTALE
material made more sense
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DELTA test of speech offset
Unfortunately no clear conclusion
could be drawn from the tests
Other than differences between the
headphones seems to be limited
And that no offered value was spot on
So we decided to stick to the 20 dB
offset, unless really good arguments
suggested another value.
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Attenuation of background noise
Requriements of maximum background noise levels are based upon
the dampning of TDH-39.
In ISO 8253-1:2010 maximum background levels for TDH-39 are
given along with the dampening factor of TDH-39, ER-3A og HDA
200.
Attenuation values for ER-3A og Ear 5A is assumed idenical, as the
yellow foam plug is the same for both earphones
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Attenuation of background noise II
Attenuation values of new headphones should be published and then
requirements for background noise levels can be calculated.
In Denmark practise have been that the TDH-39 headphone have
been build-in a sound attenuating cup (i.e from a hearing protector)
Official attenuation values are not given for these constructions,
The supraaural TDH-39 is in this way turned into a circumaural
headphone !
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Dæmpningsværdier for HD280*
HDA280 Schalldämmung / Sound attention
Frequency
(Hz)
df in dB on
B&K 4153
df in dB on
Head and Torso
4128C
125
250
500
750
1000
1500
2000
3150
4000
5000
0
0
0
0
0
6dB
12dB
15dB
23dB
31dB
0
0
0
0
3dB
6dB
10dB
12dB
20dB
6300
8000
27dB
26dB
25dB
27dB
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* Fra mail korrespondance med Sennheisser
RETSPL for different headphones
Traditionally all audiometers in Denmark have had TDH39 og
ER-3A head/earphones.
RETSPL on 60318-3(6CC) og 60318-1 couplers can be found
in ISO 389-1 (Table 1 og 2) for THD-39
And in ISO389-2 on IEC60318-4(711) and IEC60318-5(2CC)
for ER-3A insert phones
HDA200 entered in the High-frequency standard ISO389-5,
now it is in u: ISO389-8:2004 table 1-)
Ear 5A is commonly accepted as it has the RETSPL according
to ER-3A (but are’nt really mentioned in the standard)
Supraaurale Headphone types, not mentioned above can be
measured on the IEC60318-1, coupler according to ISO 3891, where RETSPL for these headphones is given in table 2
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ISO 389-1 excerpts :
…
- ISO 389-8: Circumaurale HP (only Sennheisser HDA 200)
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New headphones emerges
New headphones are seen in Denmark: DD45 (TDH39 Clone) and
HD280
Rumor has that a new sennheisser is on its way
Supraaural headphones are in priciple covered in ISO 389-1 table 2,
where RETSPL for these headphones is given on the IEC60318-1,
coupler
Circumaural headphones are covered in ISO 389-8, but only HDA 200
can be used ?
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DD45 W. Demand
(Claus Elberling)
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Audiometer measurement I
TDH-39
Reference
Frekvens
(Hz)
dB HL
L
A
R
L
B
R
L
C
R
L
D
R
L
R
60
125
0,0
0,0
-2,9
-3,0
-1,7
-1,8
-1,6
-1,8
-0,2
-0,3
80
250
0,0
0,0
0,6
0,6
-0,6
-0,7
-1,0
-1,2
-0,3
-0,2
90
500
0,0
0,0
1,2
1,3
0,4
0,4
-1,0
-1,1
-0,5
-0,4
90
750
0,0
0,0
1,0
1,2
0,1
0,1
-1,0
-1,1
-0,3
-0,2
90
1000
0,0
0,0
0,7
0,8
0,1
0,2
-1,0
-1,0
-0,2
-0,1
90
1500
0,0
0,0
0,3
0,7
-0,1
0,0
-1,2
-1,1
-1,4
-1,5
90
2000
0,0
0,0
0,6
0,4
0,1
0,0
-0,9
-1,0
0,6
0,5
90
3000
0,0
0,0
2,6
2,8
0,3
0,4
-0,9
-1,0
-0,3
-0,3
90
4000
0,0
0,0
2,3
2,5
0,6
0,7
-0,7
-0,7
-0,1
-0,2
90
6000
0,0
0,0
-4,7
-7,9
0,9
0,8
-1,4
-1,5
-1,5
-1,4
90
8000
0,0
0,0
0,7
2,0
-0,1
0,3
-1,7
-1,5
-0,4
-0,7
Variation sabove 1,5 dB
Variations above limit
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Audiometer measurement II
EAR-3A
Reference
Frekvens
(Hz)
dB HL
L
A
R
L
B
R
L
C
R
L
R
60
125
0,0
0,0
-0,2
-0,5
-0,1
0,0
0,0
0,0
80
250
0,0
0,0
-0,4
-0,4
-0,3
-0,2
-0,1
-0,1
90
500
0,0
0,0
-0,2
-0,2
0,2
0,2
-0,1
-0,1
90
750
0,0
0,0
-0,2
-0,3
0,2
0,3
-0,2
-0,1
90
1000
0,0
0,0
-0,1
-0,3
0,7
0,7
-0,1
-0,2
90
1500
0,0
0,0
0,0
-0,4
1,7
1,8
-0,1
-0,1
90
2000
0,0
0,0
0,1
-0,6
2,8
2,8
0,0
0,0
90
3000
0,0
0,0
0,4
-0,8
1,8
1,9
0,4
0,6
90
4000
0,0
0,0
-1,1
-1,5
-4,4
-3,7
1,0
1,3
90
6000
0,0
0,0
-0,9
-0,9
3,3
3,4
0,8
0,8
90
8000
0,0
0,0
-0,1
-0,7
-1,7
-1,6
0,1
0,2
Variation sabove 1,5 dB
Variations above limit
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Audiometer measurement III
HDA-200
Reference
Frekvens
(Hz)
dB HL
L
A
R
L
B
R
L
C
R
L
R
60
125
0,0
0,0
-0,1
0,0
-0,4
-0,5
0,0
-0,1
80
250
0,0
0,0
-0,2
0,1
-0,2
-0,2
-0,4
-0,3
90
500
0,0
0,0
-0,3
-0,1
-0,3
-0,3
-0,2
-0,3
90
750
0,0
0,0
-0,4
-0,2
-0,4
-0,6
-0,4
-0,6
90
1000
0,0
0,0
-0,5
-0,3
-0,6
-0,6
-0,4
-0,6
90
1500
0,0
0,0
-0,7
-0,5
-1,1
-0,7
-0,8
-0,9
90
2000
0,0
0,0
-0,7
-0,5
-1,0
-1,0
-0,3
-1,0
90
3000
0,0
0,0
-1,8
-1,7
-1,5
-1,8
-1,4
-2,1
90
4000
0,0
0,0
-1,0
-0,6
-0,7
-0,9
-0,7
-1,0
90
6000
0,0
0,0
-0,2
0,1
-0,5
0,3
-0,1
0,2
90
8000
0,0
0,0
-0,1
0,2
-0,2
-0,4
-0,2
0,0
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Variation sabove 1,5 dB
Variations above limit
Audiometer measurement IIII
BC-71
Frekvens
(Hz) Reference
dB HL
A
C1
C2
D
30
250
0,0
-0,8
-0,5
-4,7
0,7
40
500
0,0
-0,1
-2,9
-4,0
0,4
40
750
0,0
-0,2
-2,4
-4,4
0,5
50
1000
0,0
0,0
-2,4
-4,6
0,7
50
1500
0,0
-0,6
-2,1
-5,6
0,9
50
2000
0,0
-0,7
-3,0
-4,5
0,1
50
3000
0,0
-0,5
-1,2
-2,6
0,0
50
4000
0,0
-3,4
0,8
-6,5
0,4
40
6000
0,0
2,0
-4,4
-4,5
-0,2
Variation sabove 1,5 dB
Variations above limit
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