Assessing the effectiveness of the Path Medical QSCREEN ® Adaptive Noise Cancellation Technology on various DPOAE test parameters (overall test time, overall pass/refer, test time and pass/refer rate per frequency).

1. Recording Distortion
Product Otoacoustic
Emissions (DPOAEs)
using the Adaptive
Noise Cancellation
algorithm
Ricardo Vallejo, BS.Ed.
Jacek Smurzynski, Ph.D.

2. 01
Introduction

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

8. 02
Materials and
Methodology

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
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