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CONVERSATION WITH A COLLEAGUE To test this, we would need to obtain female midshipman collected during the nonreproductive period and record from their saccules. I conspired with Paul Forlano, who was a graduate student at the time in Andy’s lab and is now a professor at Brooklyn College, a campus of the City University of New York, and he helped me convince Andy to pay for a trip to collect winter, nonreproductive female midshipman in Monterey Bay, California. The problem was that during the nonreproductive season, midshipman move offshore into deeper waters and can be found at about 80 to 100 meters deep. To collect mid- shipman at these depths, we needed to charter a boat and collect fish offshore using an otter trawl. We only managed to collect 22 nonreproductive females and sent them back to the Bass lab for auditory saccular record- ings. After a few saccular recordings from those females, we arrived at that “Eureka” moment and realized that nonreproductive and reproductive females were tuned differently and that seasonal changes in the auditory sen- sitivity of adult animals did indeed exist! Later, we found that the saccules of reproductive females were more sensitive to higher frequencies within the midshipman hearing range, which meant that summer reproductive females were better able to detect the higher harmonic components in the male advertisement call. This seasonal enhancement and plasticity of the audi- tory system likely enhanced the detection and location of potential mates by females during the breeding season. The next big challenge was trying to determine the mech- anism responsible for the observed changes in auditory sensitivity. Based on earlier work, including my dis- sertation research, we decided to investigate the role of gonadal steroids (androgens and estrogen) as potential modulators of auditory sensitivity. However, at the time, we had no idea about how gonadal steroid levels changed seasonally in the midshipman fish. We decided to undertake a two-year study to document and characterize how androgen and estrogen levels changed during the midshipman reproductive cycle. This was not an easy task. It required us to collect blood samples and determine midshipman hormone levels at different time points throughout the year and cor- relate these changes with the seasonal development of the gonads in both males and females. We were able to characterize how androgen and estrogen levels changed during the annual reproductive cycle of both females and males. Interestingly, we noted that in females, both testos- terone and estrogen levels were relatively low throughout the year except for one month prior to the breeding season, when females exhibited a spike in testosterone and estrogen levels. Could it be that these spikes in hor- mone levels were responsible for inducing the sensitivity changes in the saccule? To determine if testosterone and estrogen were respon- sible for changes in auditory saccular sensitivity, we implanted winter nonreproductive female midshipman with either testosterone or estrogen to simulate the hor- mone levels that females naturally experience one month prior to the breeding season. Our results from the hor- mone implant experiments showed that nonreproductive females treated with testosterone or estrogen exhibited enhanced auditory saccular sensitivity to the dominant frequencies contained in the male advertisement calls. Furthermore, the saccular tuning profiles of the hor- mone-implanted females mimicked the saccular tuning profiles of summer reproductive females. This sensory plasticity observed in adult females was thought to pro- vide an adaptable mechanism that enhances the coupling between sender and receiver in the midshipman commu- nication system. Our work wound up being timely and was subsequently published in the journal Science. This study represents perhaps my most proud contribution to science and was truly a team effort in collaboration with Andrew Bass, Paul Forlano, and David Deitcher. Since the publication of this paper, the reported hormone-depen- dent mechanism appears to be evolutionary conserved with other studies reporting similar changes in sensory sensitivity due to gonadal steroids in adult animals from other taxa including amphibians, birds, and mammals. What are some of the other areas in which you feel you made substantive contributions over your career? These include the investigation of sound source localiza- tion by fishes, which was the topic of my first National Science Foundation grant as an assistant professor at the University of Washington. Previous evidence sug- gested that the capacity for sound source localization was common to mammals, birds, reptiles, and amphibians, 74 Acoustics Today • Summer 2022