Audiometer and Hearing Aid measurements / mini seminar

Transcription

1 Audiometer and Hearing Aid measurements / mini seminar DELTA Technical-Audiological Laboratory - TAL Edisonsvej Odense C Tlf tal@delta.dk

2 Program 14:00 Welcome and introduction/ Gert Ravn 14:10 SW Development and implementation of speech-gain measurements according IEC / Søren L Jørgensen 14:40 Future EMC measurements on Hearing Aids/ Allan G Kristensen 15:00 New aspects of hearing aid documentation according IEC and updated IEC / Gert Ravn 15:20 Audiometer calibration. Round Robin test results/ Carsten Daugaard 16:00 Closing

3 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

4 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

5 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

6 Issues in practical calibration: Speech audiometry Offset value Practical issues in speech calibration Free field calibration Attenuation of background noise RETSPL for new headphones

7 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

8 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 ISO clause 3.12 defined maximum speech recognition score SRT corresponds to some extend th the in ISO 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

9 Speech audiometry i Denmark III According to the IEC :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

10 ANSI- values for speech audiometry ANSI S 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

11 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.

12 Attenuation of background noise Requriements of maximum background noise levels are based upon the dampning of TDH-39. In ISO :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

13 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!

14 Dæmpningsværdier for HD280* HDA280 Schalldämmung / Sound attention Frequency d f in db on d f in db on (Hz) B&K 4153 Head and Torso 4128C dB dB dB 6dB dB 10dB dB 12dB dB 20dB dB 25dB dB 27dB * Fra mail korrespondance med Sennheisser

15 RETSPL for different headphones Traditionally all audiometers in Denmark have had TDH39 og ER-3A head/earphones. RETSPL on (6CC) og couplers can be found in ISO (Table 1 og 2) for THD-39 And in ISO389-2 on IEC (711) and IEC (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 IEC , coupler according to ISO 389-1, where RETSPL for these headphones is given in table 2

16 ISO excerpts : - ISO 389-8: Circumaurale HP (only Sennheisser HDA 200)

17 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 table 2, where RETSPL for these headphones is given on the IEC , coupler Circumaural headphones are covered in ISO 389-8, but only HDA 200 can be used?

18 DD45 W. Demand (Claus Elberling)

19 Audiometer measurement I TDH-39 Reference A B C D Frekvens db HL (Hz) L R L R L R L R L R ,0 0,0-2,9-3,0-1,7-1,8-1,6-1,8-0,2-0, ,0 0,0 0,6 0,6-0,6-0,7-1,0-1,2-0,3-0, ,0 0,0 1,2 1,3 0,4 0,4-1,0-1,1-0,5-0, ,0 0,0 1,0 1,2 0,1 0,1-1,0-1,1-0,3-0, ,0 0,0 0,7 0,8 0,1 0,2-1,0-1,0-0,2-0, ,0 0,0 0,3 0,7-0,1 0,0-1,2-1,1-1,4-1, ,0 0,0 0,6 0,4 0,1 0,0-0,9-1,0 0,6 0, ,0 0,0 2,6 2,8 0,3 0,4-0,9-1,0-0,3-0, ,0 0,0 2,3 2,5 0,6 0,7-0,7-0,7-0,1-0, ,0 0,0-4,7-7,9 0,9 0,8-1,4-1,5-1,5-1, ,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

20 Audiometer measurement II EAR-3A Reference A B C Frekvens db HL (Hz) L R L R L R L R ,0 0,0-0,2-0,5-0,1 0,0 0,0 0, ,0 0,0-0,4-0,4-0,3-0,2-0,1-0, ,0 0,0-0,2-0,2 0,2 0,2-0,1-0, ,0 0,0-0,2-0,3 0,2 0,3-0,2-0, ,0 0,0-0,1-0,3 0,7 0,7-0,1-0, ,0 0,0 0,0-0,4 1,7 1,8-0,1-0, ,0 0,0 0,1-0,6 2,8 2,8 0,0 0, ,0 0,0 0,4-0,8 1,8 1,9 0,4 0, ,0 0,0-1,1-1,5-4,4-3,7 1,0 1, ,0 0,0-0,9-0,9 3,3 3,4 0,8 0, ,0 0,0-0,1-0,7-1,7-1,6 0,1 0,2 Variation sabove 1,5 db Variations above limit

21 Audiometer measurement III HDA-200 Reference A B C Frekvens db HL (Hz) L R L R L R L R ,0 0,0-0,1 0,0-0,4-0,5 0,0-0, ,0 0,0-0,2 0,1-0,2-0,2-0,4-0, ,0 0,0-0,3-0,1-0,3-0,3-0,2-0, ,0 0,0-0,4-0,2-0,4-0,6-0,4-0, ,0 0,0-0,5-0,3-0,6-0,6-0,4-0, ,0 0,0-0,7-0,5-1,1-0,7-0,8-0, ,0 0,0-0,7-0,5-1,0-1,0-0,3-1, ,0 0,0-1,8-1,7-1,5-1,8-1,4-2, ,0 0,0-1,0-0,6-0,7-0,9-0,7-1, ,0 0,0-0,2 0,1-0,5 0,3-0,1 0, ,0 0,0-0,1 0,2-0,2-0,4-0,2 0,0 Variation sabove 1,5 db Variations above limit

22 Audiometer measurement IIII BC-71 db HL Frekvens (Hz) Reference A C1 C2 D ,0-0,8-0,5-4,7 0, ,0-0,1-2,9-4,0 0, ,0-0,2-2,4-4,4 0, ,0 0,0-2,4-4,6 0, ,0-0,6-2,1-5,6 0, ,0-0,7-3,0-4,5 0, ,0-0,5-1,2-2,6 0, ,0-3,4 0,8-6,5 0, ,0 2,0-4,4-4,5-0,2 Variation sabove 1,5 db Variations above limit