Comparison of Three Acoustic Test Fixtures for Impulse Peak Insertion Loss

Size: px

Start display at page:

Download "Comparison of Three Acoustic Test Fixtures for Impulse Peak Insertion Loss"

Benjamin Thomas
5 years ago
Views:

Comparison of Three Acoustic Test Fixtures for Impulse Peak Insertion Loss William J. Murphy, Gregory A. Flamme, Jacob Sondergaard, Deanna K. Meinke, Donald S.

1 Comparison of Three Acoustic Test Fixtures for Impulse Peak Insertion Loss William J. Murphy, Gregory A. Flamme, Jacob Sondergaard, Deanna K. Meinke, Donald S. Finan, James Lankford, Amir Khan, Michael Stewart Hearing Loss Prevention Team National Institute for Occupational Safety and Health The findings and conclusions in this presentation have not been formally disseminated by the National Institute for Occupational Safety and Health and should not be construed to represent any agency determination or policy.

2 A Little History Data were collected at Rudyard MI in 2010 as a part of an effort to evaluate the ANSI S12.42-2010 standard.

2 2 A Little History Data were collected at Rudyard MI in 2010 as a part of an effort to evaluate the ANSI S standard. Results from that study were presented at the 161 st meeting of Acoustical Society of America in Seattle earlier this year. Results will be published in Int. J. Aud. in Feb 2012.

3 3 A Little More History The Rudyard 2010 study evaluated the performance of 4 hearing protectors with the ISL 1-eared Test Fixture EAR Pod Express, EAR Combat Arms version 4, Etymotic Research EB-1 BlstPLG (turned off) Bilsom 707 Impact II earmuff (turned off)

4 4 Rudyard 2010 Results

5 5 Why Conduct Another Study? NIOSH evaluated early prototypes of the G.R.A.S. Sound & Vibration 45CB fixture in late 2010 and early NIOSH competed a contract to build an ANSI S12.42 fixture, awarded to French German Research Institute de Saint Louis. 45CB fixture was available April NIOSH partially funded the comparison study.

6 6 Study Purpose Measure four hearing protection devices using a gunshot as the impulse noise source with three acoustic test fixtures. Four Hearing Protector Conditions Etymotic ER20 HiFi earplug Etymotic EB-1 BlstPLG (turned on) Peltor Tactical Pro muff (turned on) Dual Tactical Pro (on) & ER20

7 7 3 Fixtures, Positions, 3 Levels, 1 Source Colt AR caliber rifle GRAS 45CB, ISL 1-ear (old), ISL 2-ear (new) ATFs Nominal peak levels: 130, 150 and 170 db SPL GRAS 45CB ISL 2-eared ISL 1-ear

8 8 ANSI S and EPA NIOSH and USAF scientists drafted a proposed method to quantify performance of level-limiting, nonlinear HPDs. The method was provided to ANSI S12 WG11 for further development.

9 9 Theory for Impulse Peak Insertion Loss L: Three Levels for each Fixture i: Five Samples of each Protector j: Five Fittings of each Protector Sample k: Three Shots for each Fitting of each Protector Sample

10 10 Etymotic Research ER-20 (HiFi) Earplug 70 Impulse Peak Insertion Loss (db) GRAS Left Ear GRAS Right Ear ISL 1-Ear ISL 2-Eared Left ISL 2-Eared Right ER Impulse Peak Level (db SPL)

11 11 Etymotic Research BlstPLG EB-1 Earplug 70 Impulse Peak Insertion Loss (db) GRAS Left Ear GRAS Right Ear ISL 1-Ear ISL 2-Eared Left ISL 2-Eared Right EB Impulse Peak Level (db SPL)

12 12 Peltor Tactical Pro Earmuff (Unity Gain) 70 Impulse Peak Insertion Loss (db) GRAS Left Ear GRAS Right Ear ISL 1-Ear ISL 2-Eared Left ISL 2-Eared Right Peltor Tactical Pro Impulse Peak Level (db SPL)

13 13 Dual Protection: Tactical Pro (Unity Gain) & Etymotic ER20 70 Impulse Peak Insertion Loss (db) Dual Tactical Pro & ER20 GRAS Left Ear GRAS Right Ear ISL 1-Ear ISL 2-Eared Left ISL 2-Eared Right Impulse Peak Level (db SPL)

14 14 Discussion of Results The three fixtures exhibit close agreement for the earplug data. The earmuff data are quite different. GRAS fixture exhibits less IPIL than the ISL fixtures Single muff ~10 db Dual protection ~20 db WHY????!!!!???

15 15 Pinna, Experimenter or Both? Good Fit Bad Fit US Army Photos by Ron Carty

16 16 Dual Protection: Tactical Pro (Unity Gain) & Etymotic ER20 (APG) 70 Impulse Peak Insertion Loss (db) Dual Protection Aberdeen Proving GRAS Left Ear GRAS Right Ear ISL 1-Ear ISL 2-Eared Left ISL 2-Eared Right Ground Impulse Peak Level (db SPL)

17 17 Relative Levels (db re maximum band) Comparison of the Free-Field 170 db Octave Band Frequencies (Hz) Impulse Spectra Rudyard170 APG165 USAARL165

18 18 Comparison of t 40 e maximum band) 30 Impulse Spectra

19 19 Comparison of the Free-Field 130 db 40 Relative Levels (db re maximum band) Rudyard130 APG130 USAARL Octave Band Frequencies (Hz) Impulse Spectra

20 20 Effects of Impulse Spectra Gunshot had more high-frequency content. Gunshot observed more IPIL Gunshots peaked at 1000 Hz Shock Tubes peaked at 250 Hz

21 21 Acknowledgement Testing was conducted at Rudyard MI with assistance from Michael Stewart, Greg Flamme, Amir Khan and Odile Clavier. Testing was conducted at Aberdeen Proving Ground MD with the assistance of Tim Mermagen, Jeremy Gaston and Joseph Echt. Testing was conducted at Fort Rucker AL with the assistance of William Ahroon, Robert Williams and Amir Khan.

22 22 QUESTIONS? Contact Information: William J. Murphy, Ph.D. National Institute for Occupational Safety & Health 4676 Columbia Parkway, MS C-27 Cincinnati, OH Portions of this work were supported by the NIOSH-EPA Interagency Agreement DW

Myths and Misconceptions about Hearing Protection E-A-R 11-13/HP. E. H. Berger, M.S.

Myths and Misconceptions about Hearing Protection E-A-R 11-13/HP E. H. Berger, M.S. M 3M Occupational Health & Environmental Safety Division E A RCAL Laboratory 7911 Zionsville Road Indianapolis, IN 46268-1657