Location
D.P. Culp Center Ballroom
Start Date
4-5-2024 9:00 AM
End Date
4-5-2024 11:30 AM
Poster Number
119
Name of Project's Faculty Sponsor
Jacek Smurzynski
Faculty Sponsor's Department
Audiology and Speech Language Pathology
Competition Type
Competitive
Type
Poster Presentation
Presentation Category
Health
Abstract or Artist's Statement
Background: A DPOAE signal must be detected in the presence of ambient acoustic noise and physiological noise arising from the patient. For testing in an unquiet environment, e.g., clinic offices or schools, attaining an advisable signal-to-noise ratio (S/N) is challenging. An effective noise reduction approach to detect DPOAEs uses weighted averaging by accepting quiet frames and applying a high weight to them while discarding frames with noise artifacts treated with low weight. A DPOAE probe of the QScreen system features two microphones to capture noise inside and outside the ear canal. An adaptive noise cancellation (ANC) algorithm includes filtering out environmental noise that passes the seal of the ear tip, resulting in an improved S/N and a reduced testing time. The study aimed to collect DPOAEs with the QScreen system under simulated noisy environment conditions to evaluate whether applying the ANC decreases the number of false positives and reduces testing time significantly. Methods: DPOAEs were recorded in 26 ears of normal-hearing young adults with a subject seated in a reclining chair outside the audiometric booth. The tests were performed with the ANC turned off and on under three conditions: 1. without presenting any signals from loudspeakers of an audio system (ambient noise level ≈35 dBA); 2. with a cafeteria noise presented at 60 and 70 dBA, and 3. with Fastl noise [1] presented at 50, 60, and 70 dBA. The volume of the sound system was adjusted to reach the target level of the noise signal with a sound level meter placed close to the entrance of the ear canal. DP-grams were recorded for the f2 frequency of 1, 1.5, 2, 3, 4, and 6 kHz with the primaries L1=61/L2=55 dB SPL. Minimum and maximum recording time per frequency was set at 2.1 and 15.2 sec. If S/N>9dB was not reached after the maximum averaging time, the data point was considered a “refer”. The overall pass criterion required at least 4 “pass” results out of 6 frequencies tested. Results: The ANC benefit increased with increasing noise level for both Fastl and cafeteria noise, with a minimal benefit in the ambient noise condition. Applying the ANC reduced testing time by up to a quarter, i.e., the median time benefit was up to 35 sec. For Fastl noise presented at 70 dBA, >70% of initial overall “refer” changed to “pass” results after applying the ANC. The highest rate of “refer” to “pass” change, as well as the greatest decrease of testing time, occurred for f2 = 1, 1.5, and 2 kHz with the ANC turned on. Conclusions: The ANC algorithm using the second microphone pointing outwards for capturing ambient noise and the primary microphone for capturing the DPOAE response in the ear canal decreases the impact of the environmental noise without influencing the DPOAE response. The benefits include: 1. reduced number of false positives, i.e., an improvement of specificity; 2. shorter testing time, and 3. a possibility of performing the screening of cochlea function based on DPOAE tests in adverse environmental conditions.
Recording Distortion Product Otoacoustic Emissions using the Adaptive Noise Cancelling Algorithm
D.P. Culp Center Ballroom
Background: A DPOAE signal must be detected in the presence of ambient acoustic noise and physiological noise arising from the patient. For testing in an unquiet environment, e.g., clinic offices or schools, attaining an advisable signal-to-noise ratio (S/N) is challenging. An effective noise reduction approach to detect DPOAEs uses weighted averaging by accepting quiet frames and applying a high weight to them while discarding frames with noise artifacts treated with low weight. A DPOAE probe of the QScreen system features two microphones to capture noise inside and outside the ear canal. An adaptive noise cancellation (ANC) algorithm includes filtering out environmental noise that passes the seal of the ear tip, resulting in an improved S/N and a reduced testing time. The study aimed to collect DPOAEs with the QScreen system under simulated noisy environment conditions to evaluate whether applying the ANC decreases the number of false positives and reduces testing time significantly. Methods: DPOAEs were recorded in 26 ears of normal-hearing young adults with a subject seated in a reclining chair outside the audiometric booth. The tests were performed with the ANC turned off and on under three conditions: 1. without presenting any signals from loudspeakers of an audio system (ambient noise level ≈35 dBA); 2. with a cafeteria noise presented at 60 and 70 dBA, and 3. with Fastl noise [1] presented at 50, 60, and 70 dBA. The volume of the sound system was adjusted to reach the target level of the noise signal with a sound level meter placed close to the entrance of the ear canal. DP-grams were recorded for the f2 frequency of 1, 1.5, 2, 3, 4, and 6 kHz with the primaries L1=61/L2=55 dB SPL. Minimum and maximum recording time per frequency was set at 2.1 and 15.2 sec. If S/N>9dB was not reached after the maximum averaging time, the data point was considered a “refer”. The overall pass criterion required at least 4 “pass” results out of 6 frequencies tested. Results: The ANC benefit increased with increasing noise level for both Fastl and cafeteria noise, with a minimal benefit in the ambient noise condition. Applying the ANC reduced testing time by up to a quarter, i.e., the median time benefit was up to 35 sec. For Fastl noise presented at 70 dBA, >70% of initial overall “refer” changed to “pass” results after applying the ANC. The highest rate of “refer” to “pass” change, as well as the greatest decrease of testing time, occurred for f2 = 1, 1.5, and 2 kHz with the ANC turned on. Conclusions: The ANC algorithm using the second microphone pointing outwards for capturing ambient noise and the primary microphone for capturing the DPOAE response in the ear canal decreases the impact of the environmental noise without influencing the DPOAE response. The benefits include: 1. reduced number of false positives, i.e., an improvement of specificity; 2. shorter testing time, and 3. a possibility of performing the screening of cochlea function based on DPOAE tests in adverse environmental conditions.