Recording Distortion Product Otoacoustic Emissions using the Adaptive Noise Cancellation Algorithm
- 1. Recording Distortion Product Otoacoustic Emissions (DPOAEs) using the Adaptive Noise Cancellation algorithm Ricardo Vallejo, BS.Ed. Jacek Smurzynski, Ph.D.
- 3. ● DPOAEs are an efficient and non-invasive tool for detecting hearing impairment associated with outer hair cell (OHC) dysfunctions. (Zurek et al., 1982) ● DPOAEs can be customized to assess frequencies in reference to a patient’s audiogram and may be more sensitive for detecting high-frequency hearing loss than pure-tone audiometry. (Martin et al., 2012) ● As a result, DPOAEs are a widely used clinical tool when performing hearing evaluations, hearing screenings, and when making clinical diagnoses of hearing loss in conjunction with other audiologic tests. (Barker et al., 2000; Job & Nottet, 2002; Shiomi et al., 1997) Distortion Product Otoacoustic Emissions (DPOAEs)
- 4. ● When measuring DPOAEs, a pair of primary tones at frequencies f1 < f2 is delivered via two earphones inserted in the ear canal. ● The most prominent distortion product occurs at 2f1 − f2 and it can be recorded by a probe microphone placed in the ear canal (Harris et al., 1989). ● The primary tones' excitation patterns mainly overlap near the f2 characteristic place in the cochlea, the sound-pressure level (SPL) of DPOAE at fDP = 2f1 − f2 represents the cochlea's ability to process signals normally at frequency f2 (Kanis & de Boer, 1994). ● DPOAE levels typically peak at f2/f1 ratios of 1.22 and can reflect the cochlea's frequency selectivity and bandpass filter function or properties (Allen & Fahey, 1993; Harris et al., 1989). Distortion Product Otoacoustic Emissions
- 5. Background Studies • The effects of ambient noise on DPOAE measurement were examined in 20 normal hearing adults as a function of averaging time and test frequency. • DPOAEs were measured at nine ambient noise levels from the baseline to 65 dBA, at four different averaging times for f2 ranging from 0.7 to 6 kHz. Findings • To achieve desired SNR for DPOAE presence, longer averaging times were required as noise level increased and as frequency decreased. • Higher noise levels affected SNR significantly in the low frequencies. • Higher noise levels (up to 65 dBA) did not have as much of an effect on the SNR for high frequencies. Lee et al. (1996) Effects of noise on Distortion Product Otoacoustic Emission measurement. South Korea.
- 6. Findings ● Among the transducers tested, the standard earmuff significantly reduced the amount of time needed to screen DPOAEs from 1000-5000 Hz, in background noise at or above 60 dBA. ● Both the standard earmuff and active noise cancellation headphones reduced the number of referrals at 1 Hz and 2 kHz in background noise at or above 60 dBA. • Compared the effect of active noise cancellation headphones and standard earmuffs on the ability to measure DPOAEs (1-5 kHz) in the presence of background noise. • Utilized ambient noise, and 40 dBA, 60 dBA, and 80 dBA speech babble. • Analyzed test time and pass/refer per frequency. Background Studies Nielsen et al. (2011) Effects of noise attenuation devices on screening Distortion Product Otoacoustic Emissions in different levels of background noise. U.S.A.
- 7. ● The goal was to assess the effects of noise cancellation technology on DPOAE test parameters (test time, pass/refer) using various auditory stimuli to mimic environmental noise of different levels. ● Assessing the clinical efficacy of such noise cancellation technology for its application in adverse testing environments (schools, hospitals, pediatric offices) where background noise may be a concern. Rationale for Study
- 9. ● Larson Davis 824 Sound level meter ● Standard audio system with a CD player ● FASTL audio file ● Cafeteria noise audio file ● QScreen device Materials
- 10. ● QScreen intended for recording of otoacoustic emissions (TEOAEs & DPOAEs), auditory brainstem response (ABR), auditory steady-state response (ASSR) tests ● Hand-held device with a docking station ● Data exchange using Bluetooth ● Integrated camera for scanning barcodes, etc. ● Uses innovative adaptive noise cancelling technology with the goal of improving SNR Path Medical QScreen
- 11. ● LT probe features two microphones ○ Mic 1 captures the response within the ear canal and Mic 2 captures the environmental noise ● Noise cancellation technology filters and adjusts the ambient noise signal to produce a virtual replica of the ambient noise reaching the ear canal and then subtracts this output from the primary signal ● Follows changes of the noise and reduces test time by a factor of up to 10 in noisy surroundings Active Noise Cancellation (ANC)
- 12. ANC In Use
- 13. ANC In Use
- 14. Fastl Noise versus Cafeteria Noise For speech-audiometric measurements a specific noise was developed with spectral distribution and temporal envelope fluctuation corresponding, on the average, to those of running speech. The fluctuation of the envelope of this noise reflects the sensitivity of the hearing system to different frequency fluctuations. As to the impairment of the word intelligibility, Fastl noise ranges between the extreme cases of “competing speech” and “cocktail party noise”.
- 15. Audio Samples Fastl Noise Cafeteria Noise
- 16. 1. Test parameters for DPOAE recordings a. Frequencies tested f2 = 1, 1.5, 2, 3, 4, 6 kHz b. L2= 61, L1=55 dB SPL; f2/f1=1.22 c. Minimum SNR of 9 dB d. Pass: 4 out of 6 frequencies e. Minimum recording time per frequency of 2.1 seconds f. Maximum recording time per frequency of 15.2 seconds a. If reached, frequency considered a refer g. Required pass for probe test check Methods
- 17. 2. Sound level meter measurements were made for the following levels for the various stimuli, with the SLM adjacent to the seated subject a. 35 dBA for ambient noise (general recording of ambient noise in room) b. 50 dBA, 60 dBA, and 70 dBA for FASTL noise c. 60 dBA and 70 dBA for Cafeteria noise Methods
- 18. 3. In a fixed seated position, DPOAE testing was performed at the aforementioned levels/stimuli with ANC activated/deactivated 4. Recordings were then repeated per ear each for test/retest reliability 5. Results were analyzed based on the following test parameters for all conditions: a. Overall test time b. Test time per frequency c. Change in overall pass/refer with ANC activated/deactivated d. Change in pass/refer per frequency with ANC activated/deactivated Methods
- 19. ● Requirements ○ Normal middle ear function and normal pure tone audiogram from 250 Hz to 8,000 Hz ● Participants ○ Number of ears: 52 ○ Age range: 22-27 years ○ Two of the subject’s recordings were omitted due to absent DPOAEs in that respective ear or history of middle ear pathology Participants & Requirements
- 20. 03 Results
- 21. QScreen probe measurement of environmental noise performed once per second
- 22. ANC Benefit Key: F50 – Fastl Noise 50 dBA F60 – Fastl Noise 60 dBA F70 – Fastl Noise 70 dBA C60 – Cafeteria Noise 60 dBA C70 – Cafeteria Noise 70 dBA
- 23. Overall Test Time Difference Overall Pass/Refer Change
- 24. Test Time Difference Pass/Refer Change Ambient Noise ~35 dBA
- 25. Fastl Noise 50 dBA Test Time Difference (refer/refer excluded) Test Time Difference
- 26. Pass/Refer Change Fastl Noise 50 dBA
- 27. Fastl Noise 60 dBA Test Time Difference Test Time Difference (refer/refer excluded)
- 28. Pass/Refer Change Fastl Noise 60 dBA
- 29. Fastl Noise 70 dBA Test Time Difference (refer/refer excluded) Test Time Difference
- 30. Pass/Refer Change Fastl Noise 70 dBA
- 31. Cafeteria Noise 60 dBA Test Time Difference Test Time Difference (refer/refer excluded)
- 32. Pass/Refer Change Cafeteria Noise 60 dBA
- 33. Cafeteria Noise 70 dBA Test Time Difference (refer/refer excluded) Test Time Difference
- 34. Pass/Refer Change Cafeteria Noise 70 dBA
- 35. 04 Conclusions
- 36. ● ANC benefit increases with increasing noise level for both Fastl noise and Cafeteria noise; minimal benefit in ambient noise. ● Greatest overall test time difference for the F60 noise condition; median = 35 seconds. ● Greatest change in overall Pass/Refer was for the F70 and C70 noise conditions. ● Across conditions, the highest Refer to Pass change occurred for f2 = 1, 1.5, and 2 kHz with ANC activated. ● Across conditions, test time difference was greatest for f2 = 1, 1.5, and 2 kHz with ANC activated.
- 37. ● TEOAEs have been recorded but accessing and analyzing the results will be possible after the initial data processing performed by the team of Path Medical is completed. ● Clinical application of the device Future Direction
- 38. References Allen, J. B., & Fahey, P. F. (1993). A second cochlear‐frequency map that correlates distortion product and neural tuning measurements. The Journal of the Acoustical Society of America, 94, 809–816. https://doi.org/10.1121/1.408182 Barker, S. E., Lesperance, M. M., & Kileny, P. R. (2000). Outcome of newborn hearing screening by ABR compared with four different DPOAE pass ariteria. American Journal of Audiology, 9, 142–148. https://doi.org/10.1044/1059-0889(2000/017) Fastl, H. (1987). A background noise for speech audiometry. Audiologische Akustik, 1-10.
- 39. References Harris, F. P., Lonsbury‐Martin, B. L., Stagner, B. B., & Martin, G. K. (1989). Acoustic distortion products in humans: Systematic changes in amplitude as a function of f2/f1 ratio. The Journal of the Acoustical Society of America, 85, 220–229. https://doi.org/10.1121/1.397728 Job, A., & Nottet, J.-B. (2002). DPOAEs in young normal-hearing subjects with histories of otitis media: Evidence of sub-clinical impairments. Hearing Research, 167, 28–32. https://doi.org/10.1016/S0378-5955(02)00330-1 Kanis, L., & de Boer, E. (1994). Two‐tone suppression in a locally active nonlinear model of the cochlea. The Journal of the Acoustical Society of America, 96, 2156–2165. https://doi.org/10.1121/1.410157
- 40. References Konrad-Martin, D., Reavis, K. M., McMillan, G. P., & Dille, M. F. (2012). Multivariate DPOAE metrics for identifying changes in hearing: Perspectives from ototoxicity monitoring. International Journal of Audiology, 51(Suppl 1), S51–S62. https://doi.org/10.3109/14992027.2011.635713 Lee, H. L., Lee, S. H., & Moon, S. P. (1996). Effects of Noise on Distortion Product Otoacoustic Emission Measurement. Korean J Otorhinolaryngol- Head Neck Surg, 39, 1669–1677. http://www.kjorl.org/journal/view.php?number=7654 Nielsen, K., Kreisman, B. M., Pallett, S., & Kreisman, N. V. (2011). Effects of noise attenuation devices on screening Distortion Product Otoacoustic Emissions in different levels of background noise. Journal of Educational Audiology, 17, 53-61.
- 41. References Shiomi, Y., Tsuji, J., Naito, Y., Fujiki, N., & Yamamoto, N. (1997). Characteristics of DPOAE audiogram in tinnitus patients. Hearing Research, 108, 83–88. https://doi.org/10.1016/S0378-5955(97)00043-9 Young, A., & Ng, M. (2023). Otoacoustic Emissions. In StatPearls. StatPearls Publishing. http://www.ncbi.nlm.nih.gov/books/NBK580483/ Zurek, P. M., Clark, W. W., & Kim, D. O. (1982). The behavior of acoustic distortion products in the ear canals of chinchillas with normal or damaged ears. The Journal of the Acoustical Society of America, 72, 774–780. https://doi.org/10.1121/1.388258