보청기의전기음향적성능분석. Kyoung Won Lee, Ph.D Hallym University of Graduate Studies

Transcription

1 보청기의전기음향적성능분석 Kyoung Won Lee, Ph.D Hallym University of Graduate Studies

2 차례 I. 성능분석이필요한이유 II. 성능분석에필요한장비의구성 III. 성능분석시구성품의위치 IV. 성능분석의기준 V. 성능분석의내용 VI. 성능분석의절차

3 I. 성능분석이필요한이유 보청기의품질관리보청기의적합 - frequency response & OSPL90 - compression threshold & compression ratio - attack time & release time 사용하는보청기의이상유무판단

4 II. 성능분석에필요한장비의구성 신호음발생기내부스피커 Coupler Reference microphone Measuring microphone 분석장치출력장치 ( 모니터, 프린터 ) FONIX: Frye Electronics, INC Verifit: Audioscan Aurical Free Fit: Otometrics UNITY2: Siemens

5 II. 성능분석에필요한장비의구성 - 커플러 HA-1 type HA-2 type CIC type Open type MZ couplers (Occl.) 6-cc coupler

6 III. 성능분석시구성품의위치커플러와연결 BTE Custom hearing aid ITE, ITC, CIC

7 III. 성능분석시구성품의위치커플러와연결 Ref. Mic Ref. Mic Custom hearing aid ITE, ITC, CIC BTE BTE Custom hearing aid

8 III. 성능분석시구성품의위치커플러와연결 RIE RIC Open type Pocket type CROS or FM Hearing aid

9 IV. 성능분석의기준 IEC ANSI JIS KSA 기본조건 : 난청인의청취환경및신체적조건등사용자의특성을고려

10 IV. 성능분석기준 IEC (ANSI S3.22) Measurement of the performance characteristics of air-conduction hearing aids based on a freefield technique and measured with an acoustic coupler. Described are the recommended methods of measurement for the evaluation of the electroacoustical characteristics of hearing aids e.g. for type testing and manufacturer data sheets. IEC Head and torso simulator for the measurement of air-conduction hearing aids : Measurement of the performance characteristics of hearing aids for production, supply and delivery quality assurance purposes. IEC Methods of measurement of performance characteristics of hearing aids under simulated in situ working conditions. IEC (ANSI S3.42) A recommended speech-like test signal, the International Speech Test Signal (ISTS), and a method for the characterization of hearing aids using this signal with the hearing aid set to actual user settings or to the manufacturers' recommended settings for one of a range of audiograms. For the purposes of this standard the hearing aid is considered to be a combination of the physical hearing aid and the fitting software which accompanies it.

11 V. 성능분석의내용 IEC & ANSI S3.22 (HFA) OSPL 90 최대성능 (HFA) full-on gain Basic frequency response Frequency range Battery current 사용자조건을고려 Total harmonic distortion Equivalent input noise CT & CR (I/O function curve) AT & RT * Reference test setting & reference test gain

12 VI. 성능분석의절차 IEC & ANSI S3.22 (HFA) OSPL90 ; program and or set the gain control to full-on and set other controls ; input sound pressure level : 90 db SPL (HFA) full-on gain ; program and or set the gain control to full-on and set other controls ; input sound pressure level : 50 db SPL HFA (high-frequency average) average of gain or SPL in decibels at Hz, Hz and Hz

13 VI. 성능분석의절차 IEC & ANSI S3.22 Basic response curve & Frequency range ; program and or set the gain control to the RTS and set other controls. ; keeping the input sound pressure level constant at 60 db. ; determine the lowest (f1) and highest (f2) frequencies at which the frequency response curve has the value of HFA output level minus 20 db

14 VI. 성능분석의절차 IEC & ANSI S3.22 Battery current ; Program and or set the gain control to the RTS and set other controls. ; Measure the current with an input sound pressure level of 65 db at Hz.

15 VI. 성능분석의절차 IEC & ANSI S3.22 Total harmonic distortion ; program and or set the gain control to the RTS and set other controls. ; measure and state total harmonic distortion in percent at the frequencies and levels as outlined in Table 2. ; in the event the specified frequency response curve rises 12 db or more between any distortion test frequency and its second harmonic, distortion tests at that frequency may be omitted. ; measurements below 200 Hz are not required. Table 2. Distortion test frequencies and input sound pressure levels Test frequency Input SPL 500 Hz 70 db 800 Hz 70 db 1600 Hz 65 db 3200 Hz 60 db

16 VI. 성능분석의절차 IEC & ANSI S3.22 Equivalent input noise The broadband equivalent input noise is measured by: ;program and or set the gain control to RTS and set other controls as stated. ; determine the HFA gain for an input SPL of 50 db. ; switch off the input sound source ; measure the total steady state output noise sound pressure level using a measurement bandwidth according to the frequency span of 200 Hz to Hz (or 200 Hz to Hz for a reduced bandwidth) and an averaging time of at least 0,5 sec. ; calculate the equivalent input noise level according to formula: equivalent input noise = (total output noise SPL) minus (HFA output gain for an input SPL of 50 db). If low-level expansion is active in the hearing aid during the measurement, this condition shall be stated by the manufacturer.

17 VI. 성능분석의절차 IEC & ANSI S3.22 Attack time & release time These measurements shall be performed at Hz and may also be performed at one or more of the following test frequencies: 250 Hz, 500 Hz, Hz, Hz, Hz. ; program and or set the gain control to RTS and set other controls. ; select an AGC test frequency with the input sound pressure level alternating between 55 db and 90 db. ; measure acoustic coupler SPL over time; the duration at each level has to be sufficiently long to allow output signal to reach steady state conditions ; determine attack time from time plot of the envelope of acoustic output. The attack time is defined as the time span from the level change from 55 db to 90 db SPL to the point where the signal has stabilized within 3 db. ; determine release time from time plot of the envelope of acoustic output. ; The release time is defined as the time span from the level change from 90 db to 55 db SPL to the point where the signal has stabilized to within 4 db.

18 VI. 성능분석의절차 IEC & ANSI S3.22 Steady state input-output characteristics (CT & CR) These measurements shall be performed at Hz and may also be performed at one or more of the following test frequencies: 250 Hz, 500 Hz, Hz, Hz, Hz. ; program and or set the gain control to RTS and set other controls. ; measure the acoustic coupler SPL for input sound pressure levels in the range from at least 50 db to at least 90 db, in steps not greater than 5 db, at each of the selected AGC test frequencies. ; plot the output SPL versus input SPL; use linear db scales and same size divisions for ordinate and abscissa.

19 VI. 성능분석의절차 IEC & ANSI S3.42 Test condition - The hearing aid settings are programmed as for an individual end-user, so as to characterize hearing aid performance for that individual end-user. - All settings of the hearing aid should be set to end-user settings, including noise reduction algorithms, feedback suppression systems, echo cancellation, etc. Input : international speech test signal (ISTS) ; Arabic, English, French, German, Mandarin, Spanish

20 참고문헌 IEC (ANSI S3.22). Electroacoustics - Hearing aids - Measurement of the performance characteristics of hearing aids. IEC (2005) Electroacoustics Hearing aids Measurement of the performance characteristics of hearing aids for production, supply and delivery quality assurance purposes IEC (2005) Electroacoustics Hearing aids Methods of measurement of performance characteristics of hearing aids under simulated in situ working conditions. IEC (ANSI S3.42) Testing Hearing Aids Methods for characterizing signal processing in hearing aids with a speech-like signal (a nationally adopted international standard) Fonix 7000 Hearing aid test system operator s manual (Version 1.70)

21 THANK YOU For your time