Current Status of Audiometric Device Calibration in China

Transcription

Current Status of Audiometric Device
Calibration in China
ZHONG Bo
National Institute of Metrology, China
[email protected]
Contents
1
Significance of Calibration
2
International Standards
3
Traceability System
4
Pure-tone Audiometer Calibration
5
Impedance Audiometer Calibration
6
Hearing Screening Equipment Calibration
2
1 Significance of Calibration

Hearing is one of the most important way to obtain information for
human being

As people pay more attention to hearing health, a lot of equipment
are used for audiometry, hearing disease diagnosis and recovery.
Pure-tone Audiometer
Aural Acoustic Impedance Audiometer
Hearing
Equipment

Hearing Test
Oto-Acoustic Emission Audiometer (OAE)
Auditory Brainstem Response Audiometer (ABR)
Hearing Aids
Hearing Improving
Hearing Protector
Hearing Protection
Hearing metrology aims to make the measurement accurate and
unified.
3
Pure-tone Audiometer
Normal Ear
Hearing Loss Ear
4
Aural Acoustic Impedance Audiometer
Normal Ear
Abnormal Ear
5
Oto-Acoustic Emission Audiometer
TEOAE
DPOAE
6
Auditory Brainstem Response Audiometer
7

Inaccurate device causes incorrect test results:



If actual stimulus intensity is smaller than standard value, the measured hearing
threshold will be higher, make incorrect conclusion that the ear is “not good”;
If actual stimulus intensity bigger than standard value, the measured hearing
threshold will be lower, make incorrect conclusion that the ear is “good”;
Factors to cause inaccurate device：


Device’s Electrical performance changes, for example the signal generator drifts
because of electrical components on circuit board.
Transducers’s performance changes
 Sensitivity (or Conversion efficiency)；
 Frequency Response；
Audiometers need to be calibrated regularly！！！
8
Contents
1
2
3
Traceability System
4
5
6
9
2 International Standards
The hearing standards mainly come from two international
organizations: IEC and ISO.
Hearing
Standards Classification:

Audiometric Equipments;

Calibration Device for Audiometric Equipments;

Hearing Threshold；

Audiometric Test Methods

Hearing Aids；

Hearing Protector;
Audiometric Equipments
Calibration Device for Audiometric Equipments
Hearing Threshold
Audiometric Test Methods
Hearing Aids (1)
Hearing Aids (2)
Hearing Protectors
According to these international standards, we make our
national standards and also calibration specifications.
For Example:
IEC 60645-1 Electroacoustics - Audiometric Equipment: Part 1 Pure-tone
audiometers (International Standard)
GB/T 7341.1 Electroacoustics - Audiometric Equipment- Part 1: Pure-tone
audiometers (National Standard)
JJG 388 Verification Regulation of pure-tone audiometers (Calibration
Specification)
Contents
1
2
3
Traceability System
4
5
6
19
3 Traceability System
Verification
Scheme of
Measuring
Instruments for
Audiometry
20
Primary Calibration
System for LS Microphone
Primary Calibration
System for Accelerometer
Zero Level Standards of
Air Conduction
(Ear Simulator)
Bone Conduction
(Artificial Mastoid)
Imdedance
Audiometer
NIM
Provincial
Metrology Certer
Calibration System for
Audiometer
Pure-tone
Audiometer
NIM
Speech
Audiometer
Zero Level of Air Conduction
50 Hz ~10000 Hz
U=0.7 dB (k=2)
Zero Level of Bone Conduction
250 Hz ~ 8000 Hz
U=1.0 dB (k=2)
Zero level standards of air conduction and bone conduction
Calibration System
for Audiometer
Air-Conduction
125Hz~8kHz
U=1.5dB (k=2)
Bone-Conduction
250Hz~8kHz
U=2.5dB (k=2)
Contents
1
2
3
Traceability System
4
5
6
24
4 Pure-tone Audiometer Calibration
Audiometer
Audiometer
Earphone
Vibrator
Ear Simulator
Sound Analyzer
Artificial Mastoid
Sound Analyzer
JJG 388 Verification Regulation of pure-tone audiometers
Bone Conduction
Zero Level
Distortion
Zero Level
Air Conduction
Distortion
Linearity
Narrow Band Noise
Frequency
Different earphones and different ear simulators have different Zero Levels.
Supra-aural earphones
Supra-aural earphones
High Frequency earphones
Insert earphones
Sound Field
Contents
1
2
3
Traceability System
4
5
6
32
5 Impedance Audiometer Calibration
manometer
Sound Analyzer
Audiometer
Earphone and Ear Simulator
Cavities
JJG 991 Verification Regulation of Impedance Audiometer
Frequency
Probe
Sound Pressure Level
Admittance
Pressure
Frequency
Ipsi earphone
Sound Pressure Level
Contra earphone
Distortion
Masking Sound
Admittance Calibration: (put probe into different cavities in order)
Cavities including：
0.1cc、0.2cc、0.5cc、1.0cc、2.0cc、3.0cc、4.0cc、5.0cc
Pressure Calibration: (put probe into manometer)
Measure Range: (-8 kPa ~ +8 kPa)
Accuracy: ±50 Pa
Contents
1
2
3
Traceability System
4
5
6
37
6 Hearing Screening Equipment Calibration
Calibration method of OAE (Oto-Acoustic Emission) measurement system
widely used in infants’ hearing screening
IEC 60645-6, 2009
Instruments for the measurement of
otoacoustic emissions
Stimulus
Low response signal
Sound Signal
OAE
Infant
Response
Sound Signal
Spontaneously
Problems
Stimulus and response should
be calibrated at the same time
Calibration method of AEP (Auditory Evoked Response) measurement system
widely used in Objective Hearing Evaluation
IEC 60645-7, 2009
Instruments for the measurement of
auditory brainstem responses
Stimulus
Low response signal
Sound Signal
AEP
Object
Response
Electrical Signal
Spontaneously
Problems
Stimulus and response should
be calibrated at the same time
Different manufacturer have different calibration systems. These systems
have a lot of Problems.
NIM is developing a calibration system for OAE and ABR equipment.
Prototype system has been finished, measurement experiments is doing now.
Stimulus Unit Calibration Module
According to ISO 389-6
Response Measurement Unit Calibration Module
Generate signal simulating the human ear response (OAE or ABR)
Primary Calibration
System for LS Microphone
Primary Calibration
System for Accelerometer
Air Conduction
(Ear Simulator)
Bone Conduction
(Artificial Mastoid)
Calibration System for
Audiometer
Pure-tone
Audiometer
Imdedance
Audiometer
Speech
Audiometer
OAE
Audiometer
ABR
Audiometer
Thank You for Your Attention
44

Current Status of Audiometric Device Calibration in China

Transcription

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