**5. Results**

After 30-minute in-flight, a 30-minute postflight BAER threshold estimation was run upon touchdown and with a retest 60-minute postflight to estimate threshold shifts. Results were compared to baseline thresholds. A total of seven canines (all male) were included in this study. Decibels (dB) are defined in different reference units. The dB peSPL is a decibel in sound pressure level comparing the pressure of sound at the microphone of the sound level meter to the reference pressure of 0.0002n dynes/cm2 . The results are listed in dB nHL, which is a decibel in normalized hearing level when using electrophysiologic testing, such as a BAER test. A conversation factor of 36 dB can change the dB SPL value to dB nHL with the particular IHS machine used for this study. The average threshold of baseline BAER thresholds was 27.71 dB nHL, the average of 30-minute postflight BAER thresholds was 58.35 dB HL, and the average of 60-minute postflight BAER thresholds was 46.5 dB HL. BAER thresholds increased by an average of 30.64 dB HL after 30 minutes postflight, which is equivalent to a moderate-to-severe hearing loss. BAER thresholds decreased after 60 minutes postflight by 11.85 dB HL, which is equivalent to a mild hearing loss. Dog 4 used a Zeteo Tech, Inc. snood-type canine auditory protection system (CAPS) for hearing protection, which resulted in having better thresholds 30 minutes postflight than the baseline. Dog 4 was subjected to kennel noise before baseline testing and had suspected elevated thresholds greater than expected.
