## 1 Introduction  
The tympanic membrane (TM), also known as the eardrum, is vital to hearing because it converts sound pressure waves in air into mechanical vibrations. These vibrations are then passed through the ossicular chain (the three middle ear bones) into the cochlea, where the vibrations are transduced into neural signals which our brain interprets as sound [1, 2]. The structure of the TM is important for normal hearing. Many diseases cause hearing loss by altering the TM, such as perforations [3, 4, 5, 6, 7], retraction pockets [8, 9, 10, 11], and cholesteatoma [11, 12, 13]. Other ear diseases cause hearing loss by affecting the middle ear space, which lies directly behind the TM, such as ear infections, middle ear fluid, or tumors of the middle ear. Thus, proper evaluation of the ear is critical for the diagnosis and treatment of these conditions [14]. Current medical management involves using an otoscope [15], which uses a small light with a magnifying glass to visualize the TM deep within the ear canal. However, this method of examining the ear is limited in the information it provides. It does allow the physician to see the surface of the TM. It can sometimes permit a limited ability to view the middle ear space and its underlying structures through the translucent nature of the TM. Sometimes, the illumination can be inadequate, making -otoscopy challenging. Furthermore, accurate otoscopic evaluations require extensive training and familiarity with the appearance of normal anatomy and pathology on examination, with conclusions often depending based on physician experience. Thus, making the clinical diagnosis of an ear infection is surprisingly fraught with difficulty, and it is common for this to be missed by routine clinical exam [16; 17]. A potential adjunct to otoscopes that could provide additional anatomical and functional information on the TM and middle ear space to improve the diagnosis and management of ear disease is the use of Optical Coherence Tomography (OCT) [18]. OCT is an interferometry-based non-invasive imaging modality in which laser light is focused into a biological tissue of interest. The back-reflected light is analyzed to provide a depth profile of the tissue (Z-direction), which is comparable to how ultrasound works. By scanning the laser beam in the X and Y directions, 3D morphological images of the sample are obtained. OCT is already in wide clinical use in ophthalmology to help in the diagnosis and treatment of various eye pathologies [19; 20]. It is now being explored for applications within the field of otolaryngology, commonly known as Ear, Nose, and Throat [21]. Our research group has been using it to study the ear [22; 23; 24]. The theoretical benefit of OCT for imaging the human ear is that it provides a 3D image of the TM, as opposed to only the 2D surface view that one gets from looking through an otoscope. Thus, it should improve the diagnostic sensitivity for ear disease and ultimately permit machine learning approaches to automate the diagnostic process. We developed a handheld OCT device that provides 3D volumes of the ear [25] that allows one to view beyond the surface level of the TM and image deeper structures often affected by middle ear pathologies (Figure 1) [26]. However, the large, high-resolution image volume stacks are difficult to interpret. It is challenging to distinguish between the various anatomic structures within the ear (e.g., the TM, the ossicles, the cochlea), artifacts that stem from strong tissue reflections that saturate the detector, and fixed pattern artifacts that come from reflections within the optical device itself. Furthermore, the orientation of the image will vary depending on the way the physician holds the device relative to the patient and the patient's individual anatomy. Therefore, while it seems like it should be simple to collect a volume scan of a patient's ear and look at the results immediately, all these factors make it difficult to expeditiously interpret the imaging and make a clinical decision at the point of care.