Professor Emeritus — Ph.D., Indiana University
Ashbel Smith Professor Emeritus in Experimental Psychology
Hearing, sensory psychology, physiological sex differences, and physiological psychology
Dr. McFadden received his Ph.D. from Indiana University. His research Interests are sensation and perception, audition, sex differences in the auditory system, prenatal hormonal effects on the auditory system, and the effects of drugs on the auditory system.
Historically, I have been interested in various aspects of auditory performance—sound localization, masking, adaptation-like effects, and the effects of drugs and intense sound on the auditory system. In recent times, I have become interested in certain sex differences in audition and have been using the auditory system as a tool for studying hormonal effects during early development.
One measure we have used is otoacoustic emissions (OAEs), which are sounds produced in the inner ear and recorded from the ear canal. OAEs are stronger and more numerous in females than in males, and this sex difference exists in newborns, as well as in adults. We have been trying to understand the mechanisms underlying these sex differences. The evidence suggests that prenatal differences in exposure to androgens contribute to the sex difference in OAE—just as it does for other sex differences in the body and the brain. Some of this evidence comes from work on special populations of humans, such as females with male co-twins, homosexual and bisexual females, and children diagnosed with attention-deficit/hyperactivity disorder (ADHD). Also, we have recorded OAEs in spotted hyenas and rhesus monkeys that have been treated with androgenic or anti-androgenic agents during prenatal development and found them generally to be altered in the predicted direction—the greater the exposure to androgens, the weaker the OAEs.
We believe that OAEs can act as a marker for the degree of androgen exposure a person receives during early development, and thus, they have the potential to serve as an noninvasive supplemental tool for scientists interested in a wide array of topics other than audition itself. My Macintosh-based lab is equipped to synthesize and generate simple and complex auditory waveforms, and to test up to eight human subjects simultaneously in a wide array of standard psychoacoustical tasks. We also have an advanced system for recording and analyzing otoacoustic emissions. We have the capability to obtain OAE measurements from distant locations over the internet. We use LabVIEW for generating waveforms, controlling experiments, and some data analysis.
NOVA 2015 Lectures
NOTE: Different browser applications behave a little differently. The following instructions appear to work for most browsers (while some browsers do the work more automatically).
The Slides files below contain the slides displayed in class, arranged in order, two per page. When you click on a Slide file, you will be asked if you want to Open the file in Adobe Acrobat. Say yes. Now you can read the Slides or Print whichever of them you wish.
The Demo files below contain some embedded sound files and some web links for the audio and video demos used in class. When you click on a Demos file, you will be asked if you want to open it in PowerPoint. Say yes (you might need to wait a couple of minutes for the file to download). When the file is displayed in PowerPoint, I recommend clicking on "Outline" mode (on the left side, at the top of the column, next to "Slides"). Now you can see the labels for each of the demonstrations, in the order we used them in class. Click on a slide label; then move your cursor over the image of the Speaker on the slide (an embedded sound file) and a small triangle will appear; click it to start and stop the audio demonstration. (The sound on your computer needs to be turned on.) For some demonstrations, you will be provided with a web address that you can paste into your browser and thereby view those videos.
If this does not work, ask any teenager for help.
Organization of the Six NOVA Lectures
1. Background information and info about sound
2. Basics of Hearing, Conductive and Sensorineural Hearing Loss
3. Audibility, Loudness, Masking, Pitch Perception
4a. Sound Localization
4b. Congenital and Acquired Hearing Loss
5. (Tinnitus), Hearing Aids, Assistive Hearing Systems
6. Regeneration, Cochlear Implants, Brainstem Implants,
The Future, Summing Up
I became a faculty member at UT in the fall of 1967, immediately after finishing my doctoral work at Indiana University. My official retirement was in the spring of 2011, but I retained my office and continued working under the title of Professor Emeritus for several more years. At IU, I studied sensory systems in general, along with learning and memory and physiological psychology, and while I did publish in all those areas, the lion's share of my research was on human hearing. Because my dissertation advisor was James P. Egan, my academic lineage goes back directly to Wundt, the acknowledged founder of experimental psychology (Egan, Stevens, Boring, Titchener, Wundt). With slight variation, many of my contemporaries had similar lineages, so it was not until recent years that I came to value this historical link.
While still a graduate student at Indiana University, I applied for, and was awarded, an NIH post-doctoral fellowship to do auditory research with UT's Lloyd Jeffress. Before I activated that fellowship, an Assistant Professorship opened up at UT, and my mentor at IU, J.P. Egan, and others, encouraged me to take the job instead of the post-doc, in part by arguing that "teaching would not take much time." I had many occasions to remember that argument in the next couple of years—because teaching did take me a lot of time, then and throughout my career. But the job paid $10,000 and the post-doc about half of that, meaning that my wife, Nancy, could stay home with our young daughter. So I became a (very naïve) faculty member at The University of Texas at the age of 26.
That was a time of great growth and change at UT. The University had hired Gardner Lindzey as chair of Psychology with the goal of turning a sleepy, second-rate department into a top-notch one. Before I arrived, he already had hired some big names—Kenneth Spence in experimental, Janet Taylor Spence in clinical, Elliott Aronson in social—and for 1967 the department was hiring a large crop of young faculty to complement those big names and help attract good graduate students. There was special emphasis on the then-new topics of behavior genetics and psycholinguistics. My entering class consisted of at least a dozen new assistant professors and one associate professor, Philip Gough, who also was coming from IU. At the time Philip retired, he and I were the only ones left from that 1967 class of new-hires. During my career, there were several IU graduates on the UT faculty—Gerald Jacobs, Peter Polson, Coleman Merriman, Arnold Buss, Wilson Geisler, and me.
During my first year at UT, I agreed to share an existing lab with the students of Lloyd Jeffress, but when that arrangement became clumsy, Gardner Lindzey provided me with $10,000 of start-up money to build a lab of my own in some space that Jeffress was not using (a job offer from Duke University helped my cause). At that time, there were no desktop computers and the standard lab computers built by the Digital Equipment Company (DEC) were too expensive for my budget. However, DEC did sell the logic cards that went into their computers separately. So I built a lab to do auditory psychophysics using R Series DEC cards. I hired a couple of undergraduates to help, and together we wire-wrapped several interface panels and we built four listening booths that had flexibility to run different types of auditory studies depending upon the particular sets of warning lights and response buttons we installed. I was quite proud of that set-up, in large part because I designed every detail, ran every wire, soldered every joint, and wrapped most of the connections.
Having a lab was only a beginning, however, because I needed money to pay subjects. So I applied for an NIH grant, which was awarded in 1969, and that began 44 years of continuous funding by NIH. The granting agencies changed names and the grant changed names, but the funding chain was unbroken. For the last 30+ years, my grants came from the National Institute on Deafness and Other Communicative Disorders (NIDCD). Prior to that, hearing research was funded by the National Institute on Neurological Diseases and Stroke (NINDS). After a few years of NIH support, I was named to a Jacob Javits Neuroscience Investigator Award by the NINDS, and that was converted into a Claude Pepper Award of Excellence when my funding was moved to NIDCD. Those grants allowed me to hire subjects and students to help with the work, and they provided me with equipment and travel money; also, the grants provided me with summer salary, which helped considerably with the modest salaries then common in academics. Without all that financial help, I unquestionably would not have done as much research (as modest as it was) nor published as much as I eventually did. I always felt extremely thankful for the availability of those NIH grants, and I always tried to provide a maximal number of data points per dollar of grant money as an expression of my appreciation. I believe that most young investigators then had a sense of pride in American science; it gave us something to feel patriotic about when much else the government was doing at the time seemed wrong-headed to us. We were allowed to study what interested us, and we discovered a lot about how Nature works. I regard it to be a national disgrace that young scientists today must struggle so much harder to obtain research money than my generation did. All of American society suffers from this short-sighted lack of financial support for science. Surely the most important benefit of having these NIH grants was that I was able to employ Edward Pasanen as a longterm associate; he was integrally involved in essentially all the research I did over the decades, and he rightly is a co-author on most of the papers. In addition to the NIH Awards, I also was proud to receive a Minnie Stevens Piper Teaching Award. So I won a Piper and a Pepper, but no pecks or pickles; I shoulda tried harder.
My early research at UT was a continuation of work I had begun during graduate school. Generally, the topic was masking of simple auditory signals by noises of various sorts, a long-standing topic in auditory research (that continues today). The twist was that I worked primarily on masking conditions in which the binaural cues of interaural differences in level and time of arrival were present (called masking-level differences or MLDs, a research topic popularized by Lloyd Jeffress, and the primary reason I had applied for a post-doc to work with him). The same neural mechanisms that evolved to provide humans with the ability to use those two cues for localizing sounds in three-dimensional space also permitted better detection of weak sounds under certain masking conditions. One of my favorite discoveries made during this time period was that a long-standing conclusion about sound localization was wrong. Since the 1930s, auditory science had believed that humans could use the cue of interaural time difference (ITD) only at low frequencies—up to only about 1200-1500 Hz. However, by using sounds more ecologically relevant than pure tones, we showed that people can use ITDs at high frequencies just as well as at low frequencies. In my sole Science paper, we also reported that (again contrary to long-standing belief) people could hear binaural beats at high frequencies, as well as at low frequencies—as long as sounds other than pure tones were presented.
Later, I became interested in various after-effects of exposure to intense sounds—changes in loudness, changes in sound localization, etc. That work forced me to think seriously about an effect I had known about for years but never really digested. When a person is exposed to an intense pure tone for a few minutes, one consequence is a temporary hearing loss of greater or lesser magnitude depending upon the strength and duration of that tone. The surprise is that the maximum hearing loss is at a frequency about one-half octave higher than the exposure tone. That is a pretty bizarre outcome (imagine getting a bee sting on your wrist that has no effect on the wrist but produces a welt on your elbow). Essentially everyone in auditory science knew about this half-octave shift, but there was no explanation offered for it. I had an idea, I scoured the auditory literature for confirmation, and I wrote a review article arguing that the tonotopic map on the basilar membrane migrates toward the base of the cochlea as sound-pressure level increases—a dynamic tonotopic map. To my enduring regret, I published that review as a chapter in a book that sold relatively few copies, so it has not been as visible and widely available as a journal article would have been. The idea that mechanical excitation patterns migrate basally with increasing level now is an integral component of thinking about cochlear mechanics, but honestly not because of my (splendidly argued) review article, because few read it.
Our work on noise exposure also led to some studies on the short-term effects of drugs on hearing. One alarming finding was that temporary aspirin-induced hearing loss can add synergistically with temporary noise-induced hearing loss, suggesting that the two together can produce more permanent hearing loss. Another major finding was that aspirin and quinine each had the ability to (reversibly) reduce those sounds that recently had been discovered to originate in the cochlea (called otoacoustic emissions), presumably because they acted on the mechanisms underlying cochlear amplification. The loss of hearing sensitivity produced by those drugs was a second consequence of the loss of cochlear amplification. My career was transitioning from psychoacoustics, and its simple behavioral measures, to physiological manipulations and physiological measures.
During the time I was studying the effects of drugs on the auditory system, I was serving on a committee of the National Research Council—called the Committee on Hearing, Bioacoustics, and Biomechanics (CHABA). The military brought a question to CHABA about tinnitus (ringing in the ears following exposure to intense sound). Although tinnitus was well-known as a common after-effect of noise exposure, it had not been actively studied by auditory scientists; it was primarily a medical problem. CHABA agreed to review the existing literature on tinnitus and to write a report that summarized what was known and what needed to be learned. As I became increasingly engrossed in the topic, that report grew into a small book published as Tinnitus: Facts, Theories, and Treatments that is still being republished. There was no remuneration for service on CHABA, nor for producing its numerous reports; we all viewed that work to be partial payback for the government's support of our research.
Otoacoustic emissions (OAEs) were a major discovery in the late 1970s, and they continue to be a valuable research tool to this day. OAEs are sounds that originate in the cochlea and propagate retrograde through the middle-ear system into the external ear where they are recorded using sensitive microphones and averaging techniques. I became interested in the developmental origins of OAEs and decided to do a twins study to obtain an estimate of their heritability. I knew nothing about twins research nor heritability estimates, but the UT faculty included behavior-genetics folks who did, and I was fortunate to be able to convince John Loehlin to collaborate on this study (and then on several follow-up studies). We found that OAEs were about 75% heritable, about the same as IQ. While I did find that outcome interesting, I was even more intrigued by another, unanticipated finding: females with male co-twins (females from opposite-sex twin pairs) had OAEs that were like those of males, not other females. Because of what was known about OAEs, this strongly suggested that these females had been exposed to higher-than-normal levels of "male" hormones like testosterone (because they shared their prenatal environment with a male). This led me down a two-decade research path that involved our using OAEs to study numerous other special populations. We showed that rhesus monkeys and sheep have human-like sex differences in their OAEs; that spotted hyenas do not; that prenatal exposure to androgenic (or anti-androgenic) agents can masculinize (or feminize) OAEs; that ADHD boys have hyper-masculinized OAEs; that women with congenital adrenal hyperplasia (CAH) have masculinized OAEs; that women with androgen-insensitivity syndrome (AIS) have female-typical OAEs; and that homosexual and bisexual females have masculinized OAEs. We also used auditory evoked potentials (AEPs) to confirm and expand that last finding. One reason these findings are important is that OAEs and AEPs appear to be reasonably stable traits through life that are not alterable by conscious choice, suggesting that the individual and group differences we observed were determined by prenatal (presumably hormonal) processes. The OAE and AEP differences we reported for non-heterosexuals are among the strongest existing evidence that human sexual orientation has a prenatal, physiological origin, and I am pleased to have made that important contribution to knowledge. Also, our various findings on the apparent effects of hormones on the auditory system have led to a general appreciation that the auditory system has the potential to serve as a valuable, supplemental source of information about prenatal development.
While we were in the process of demonstrating that OAEs and AEPs apparently provide a window on to prenatal hormonal processes, the research of others revealed another physiological measure with similar promise. The relative lengths of the fingers are different in human males and females. For example, the lengths of the second (2D) and fourth (4D) digits are about the same in females, making the ratio of those lengths approximately 1.0. For males, however, 2D is a bit shorter than 4D, making the 2D:4D ratio about 0.95. Because this sex difference emerges early in prenatal development, it is intuitive that differential exposure to sex hormones might be involved. Because finger-length ratios (FLRs) are far more easy to measure than OAEs, I became interested in the correlation between the two domains. Perhaps only FLRs were necessary in order to establish the presence of a prenatal hormonal effect. The correlations between OAEs and FLRs turned out to be a resounding zero (different timing of hormonal exposure?), but Erin Shubel and I did document FLR differences between the sexes and between heterosexuals and non-heterosexuals, and Mary Bracht and I documented sex differences in FLR measurements taken from skeletons of baboons, chimpanzees, gorillas, and humans. We also discovered that FLR measurements made by psychologists were not welcome in anthropology journals—my only rejections over decades of publishing—but this turf warfare was absent elsewhere. In the end, I concluded that human FLRs are too subject to race/ethnic/ factors to make them widely useful for psychological research in today's multiracial society. At least now the world knows.
The final research topic I pursued before retiring was the relationship between OAEs and performance on various auditory behavioral tasks. On what behavioral tasks do people with strong OAEs differ from people with weak OAEs? OAEs proved (surprisingly) to be generally rather poor predictors of behavioral performance, but at least we were able to provide solid data demonstrating that fact. And we did stumble on to some sex and race differences. We were more successful linking OAEs to attention mechanisms. For decades, auditory science had known about a neural circuit that runs from auditory cortex down to lower brain centers, culminating in a final leg that runs from the hindbrain into the cochlea (the olivocochlear bundle). When those neurons are active, this higher-to-lower circuit causes inhibition, which suggests that the auditory cortex has the ability to control the amount and type of information it is receiving from below (a negative feedback system). This realization has led to considerable speculation over the years that this so-called efferent circuitry is involved in selective attention. Kyle Walsh's dissertation research involved monitoring a form of OAE while subjects were involved in tasks that demanded either auditory or visual attention, and sure enough, our OAE showed differences when attention was required. Interestingly, the cochlear output was inhibited whether the subject was attending to auditory or visual stimuli.
One extra-curricular activity I was involved with was the 1978 US House Committee on Assassinations' study of the Kennedy assassination. This study was motivated by a discovery of some acoustical evidence that appeared to be relevant to the question of the number of shooters in Dealey Plaza. A group of acousticians and psychoacousticians went to the site and made a number of recordings, measurements, and observations. In the end this work was for naught because the initial acoustical evidence later was shown to have been incorrectly interpreted, and there was no evidence for a second shooter that needed verification. Even so, our psychoacoustics group (headed by David M. Green) did some excellent real-world work, and it was quite interesting to be involved in an official hush-hush project of that magnitude.
I was associated with another extra-curricular activity that I believe accomplished real good for the environment and for certain other mammalian species. In the early 1990s there was a plan to introduce extremely intense sounds into the oceans of the world as a way to monitor global warming (the speed of sound depends upon the temperature of the medium). Might seem like a good idea to an engineer, but twas an extremely bad idea to most marine biologists. I was one member of a committee established by the Ocean Studies Board of the National Research Council to review the proposed work and the relevant literature on the effects of noise on marine mammals. Our report was responsible for the cancellation of the plan to ensonify the oceans, for the US Navy's greater care when using certain high-intensity sonar systems, and for greater awareness of the dangers of intense sound to ocean-bound creatures, so our committee of whale-huggers did matter.
When I first started my lab, I concentrated on providing undergraduates with employment and research experience. In the early 1970s, there was a marked shortage of academic jobs, so many new psychology PhDs were unable to enter academics as they had planned for throughout their doctoral studies. This was quite distressing to me, and it seemed immoral to continue to accept new graduate students. Because I had ample grant money, I began a strategy of hiring full- or parttime employees to help with my research. Occasionally a graduate student from another area or from Audiology would express interest in working in the lab for a time, and I took many of them in, but even after the academic market improved, I never adopted the typical strategy of seeking and recruiting new graduate students to do the lab's work. So, while I played a role in the graduate training of a number of students from Psychology and Audiology (some of whom were included on publications), I was the official dissertation advisor for only two students (Beverly Wright and Kyle Walsh), while an employer of many dozens. Throughout most of this time, Edward Pasanen was responsible for the technical side of the lab as well as contributing to all other aspects of the research endeavor, and there was a long series of absolutely excellent lab managers, the longest serving being Mindy Fisher Maloney. So, with the help of NIH, I ran a small business rather than a typical academic lab. Two post-doctoral fellows worked in the lab: Mark Yama from IU, and Craig Champlin, who later joined the UT faculty in Audiology and eventually became chairman.
One of the last services I performed for the Psychology Department was to serve as the chair of the faculty building committee when the Seay Building was being constructed. It was great fun to learn about the complex logistics associated with the construction of a modern building. Also, this allowed me to observe closehand the dedication and commitment of Gary Zuker, the department's computer and technical guru. He caught many dozen major errors in design and construction, and the Seay Building unquestionably is as excellent as it is largely because of Mr. Zuker's endless hours of poring over plans checking on details. Contrary to common belief, I had absolutely nothing to do with the fountain on the north side of the Seay Building being shaped like a cochlea. It would have been wrong of me to take advantage of my position on the building committee to unilaterally choose that lasting symbol of the building. I can only presume that someone else decided to memorialize the auditory research done by Lloyd Jeffress and me.
Elderly scientists commonly comment on how their research interests changed, sometimes greatly, over their careers. As doctoral students, they never could have predicted what topics they eventually would work on, and that experience is true in spades for me. When I was young, I would have laughed at the suggestion that someday I would be collecting physiological data from spotted hyenas, sheep, twins, ADHD children, or homosexuals, or publishing on sex differences, prenatal development, aspirin, quinine, the half-octave shift, or selective attention. Yet there was a natural sequence of questions and opportunities that led me through all those topics, if not in an especially logical order. And it was great fun. Looking for the first time at the summary data from an experiment—and being the first person in the history of the world to know some new fact—are intellectual thrills unlike any other in life. Thank you to NIH and UT for permitting those thrills. I also have been gratefully sharing thrills with my wife, Nancy, for 55 years so far.
Walsh, K.P., Pasanen, E.G. and McFadden, D. (2015) Changes in otoacoustic emissions during selective auditory and visual attention. J. Acoust. Soc. Am., 137, 2737-2757.
Wisniewski, A.B., Espinoza-Varas, B., Aston, C.E., Edmundson, S., Champlin, C.A., Pasanen, E.G., and McFadden, D. (2014) Otoacoustic emissions, auditory evoked potentials and self-reported gender in people affected by disorders of sex development (DSD).Hormones and Behavior, 66, 467-474.
Walsh, K.P., Pasanen, E.G. and McFadden, D. (2014) Selective attention reduces physiological noise in the external ear canals of humans. II: Visual attention. Hearing Research, 312, 160-167.
Walsh, K.P., Pasanen, E.G. and McFadden, D. (2014) Selective attention reduces physiological noise in the external ear canals of humans. I: Auditory attention. Hearing Research, 312, 143-159.
McFadden, D., Garcia-Sierra, A., Hsieh, M.D., Maloney, M.M., Chaplin, C.A, & Pasanen, E.G. (2012) Relationships between otoacoustic emissions and a proxy measure of cochlear length derived from the auditory brainstem response. Hearing Research, 289, 63-73.
McFadden, D., Pasanen, E.G., Leshikar, E.M., Hsieh, M.D. & Maloney, M.M. (2012) Comparing behavioral and physiological measures of combination tones: Sex and race differences. J. Acoust. Soc. Am., 132, 968-983.
McFadden, D., Garcia-Sieraa, A., Hsieh, M.D., Maloney, M.M., Champlin, C.A. and Pasanen, E.G. (2012) Relationships between otoacoustic emissions and a proxy measure of cochlear length derived from the auditory brainstem response. Hearing Research, 289, 63-73.
McFadden, D (2011) Sexual orientation and the auditory system. (Invited) Frontiers of Neuroendocrinology, 32, 201-213.
Walsh, K.P., Pasanen, E.G., and McFadden, D. Walsh, K.P., Pasanen, E.G., and McFadden, D. (2010) Overshoot measured physiologically and psychophysically in the same human ears. Hearing Research, 268, 22-37.
Dennis McFadden, Michelle D. Hsieh, Adrian Garcia-Sierra, & Craig A. Champlin (2010) Differences by Sex, Ear, and Sexual Orientation in the Time Intervals between Successive Peaks in Auditory Evoked Potentials, Hearing Research, 270, 56-64.
Walsh, K.P., Pasanen, E.G., and McFadden, D. (2010) Properties of a nonlinear version of the stimulus-frequency otoacoustic emission. J. Acoust. Soc. Am., 127, 955-969.
McFadden, D. (2009) Masculinization of the mammalian cochlea. Hearing Research, 252, 37-48.
McFadden, D. and Bracht, M.S. (2009) Sex and race differences in the relative lengths of metacarpals and metatarsals in human skeletons. Early Human Development, 85, 117-124.
McFadden, D., Pasanen, E., Valero, M.D., Roberts, E.K., and Lee, T.M. (2009) Effect of prenatal androgens on click-evoked otoacoustic emissions in male and female sheep (Ovis aries). Hormones and Behavior, 55, 98-105.
McFadden, D. (2008) What do sex, twins, spotted hyenas, ADHD, and sexual orientation have in common? Perspectives in Psychological Science, 3(4), 309-323.
Valero, M., Pasanen, E., McFadden, D. & Ratnam, R. (2008) Distortion product otoacoustic emissions in the common marmoset (Callithrix jacchus): Parameter optimization. Hearing Research, 243, 57-68.
McFadden, D., Martin, G., Stagner, B. & Maloney, M. (2008) Sex differences in distortion-product and transient-evoked otoacoustic emissions compared. Journal of the Acoustical Society of America, 125, 239-246.
McFadden, D., Pasanen, E., Valero, M., Roberts, E. & Lee, T. (2008) Dissociation between distortion-product and click-evoked otoacoustic emissions in sheep (Ovis aries). Journal of the Acoustical Society of America.
McFadden, D., Pasanen, E., Raper, J., Lange, H. & Wallen, K. (2006) Sex differences in otoacoustic emissions measured in rhesus monkeys (Macaca mulatta). Hormones and Behavior, (50), 274-284.
McFadden, D., Pasanen, E., Weldele, M., Glickman, S. & Place, N. (2006) Masculinized otoacoustic emissions in female spotted hyenas (Crocuta crocuta). Hormones and Behavior, (50), 285-292.
Loehlin, J., McFadden, D., Medland, S. & Martin, N. (2006) Population differences in finger-length ratios: Ethnicity or latitude? Archives of Sexual Behavior, (35), 739-742.
McFadden, D. & Bracht, M. (2005) Sex differences in the relative lengths of metacarpals and metatarsals in gorillas and chimpanzees. Hormones and Behavior, (47), 99-111.
McFadden, D., Loehlin, J., Breedlove, S., Lippa, R., Manning, J. & Rahman, Q. (2005) A reanalysis of five studies on sexual orientation and the relative length of the 2nd and 4th fingers (the 2D:4D ratio). Archives of Sexual Behavior, (34), 341-356.
McFadden, D., Westhafer, J., Pasanen, E., Carlson, C. & Tucker, D. (2005) Physiological evidence of hypermasculinization in boys with the inattentive type of attention-deficit/hyperactivity disorder (ADHD). Clinical Neuroscience Research, (5), 233-245.
McFadden, D. & Pasanen, E. (2004) Collecting data from afar over the Internet. Echoes, (14), 8-8.
McFadden, D. & Bracht, M. (2003, September) The relative lengths and weights of metacarpals and metatarsals in baboons (Papio hamadryas). Hormones and Behavior, (43), 347-355.
McFadden, D. & Shubel, E. (2003) The relationships between otoacoustic emissions and relative lengths of fingers and toes in humans. Hormones and Behavior, (43), 421-429.
Loehlin, J. & McFadden, D. (2003) Otoacoustic emissions, auditory evoked potentials, and traits related to sex and sexual orientation. Archives of Sexual Behavior, (32), 115-127.
McFadden, D. (2002) Masculinization effects in the auditory system. Archives of Sexual Behavior, (31), 99-111.
McFadden, D. & Shubel, E. (2002, September) Relative lengths of fingers and toes in human males and females. Hormones and Behavior, (42), 492-500.
Harkrider A.W., Champlin C. & McFadden D. (2001, September) Acute effect of nicotine on nonsmokers: I. OAEs and ABRs. Hearing Research, (160), 73-88.
McFadden, D. (2001) Otoacoustic emissions as a window onto prenatal development and sexual differentiation. Seminars in Hearing, 22, 347-360.
McFadden, D. (2000) Masculinizing effects on otoacoustic emissions and auditory evoked potentials in women using oral contraceptives. Hearing Research, (142), 23-33.
McFadden, D. & Champlin, C. (2000, September) Comparison of auditory evoked potentials in heterosexual, homosexual, and bisexual males and females. Journal of the Association for Research in Otolaryngology, (1), 89-99.
Pasanen E. & McFadden D. (2000, September) An automated procedure for identifying spontaneous otoacoustic emissions. Journal of the Acoustical Society of America, (108), 1105-1116.
McFadden, D. & Callaway, N. (1999, September) Better discrimination of small changes in commonly encountered than in less commonly encountered stimuli. Journal of Experimental Psychology: Human Perception and Performance, (25), 543-560.
McFadden, D. & Pasanen, E. (1999, September) Spontaneous otoacoustic emissions in heterosexuals, homosexuals, and bisexuals. Journal of the Acoustical Society of America, (105), 2403-2413.
McFadden, D. (1998, September) Sex differences in the auditory system. Developmental Neuropsychology, (14), 261-298.
McFadden, D. (1998) Possible hormonal contributions to sex differences in otoacoustic emissions and in hearing. In A. Palmer, A. Rees, A. Summerfield & R. Meddis (Eds.), Psychophysical and Physiological Advances in Hearing (pp.65-72). London: Whurr.
McFadden, D. & Pasanen, E. (1998, September) Comparison of the auditory systems of heterosexuals and homosexuals: Click-evoked otoacoustic emissions. Proceedings of the National Academy of Sciences USA, (95), 2709-2713.
McFadden, D., Pasanen, E. & Callaway, N. (1998, September) Changes in otoacoustic emissions in a transsexual male during treatment with estrogen. Journal of the Acoustical Society of America, (104), 1555-1558.
McFadden, D. (1998) Evidence of prenatal hormonal effects on the auditory system. Proceedings of the 16th International Congress on Acoustics and 135th meeting of the Acoustical Society of America Seattle: Proceedings of the 16th International Congress on Acoustics and 135th meeting of the Acoustical Society of America.
McFadden, D., Loehlin, J. & Pasanen, E. (1996, September) Additional findings on heritability and prenatal masculinization of cochlear mechanisms: Click-evoked otoacoustic emissions. Hearing Research, (97), 102-119.
McFadden, D. & Loehlin, J. (1995, September) On the heritability of spontaneous otoacoustic emissions: A twins study. Hearing Research, (85), 181-198.
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