Additive Manufactured Ear Pinna for Spatial Cue Preservation in Custom Hearing Devices
Advancements in additive manufacturing/3D printing technologies has permitted the fabrication of intricate features such as the ones present in the human ear. The outer ear, also known as the pinna, allows for the spectral cues from incoming sound to be captured and identified. The hypothesis of the preservation of auditory localization and externalization relies on the fabrication of an ear pinna via additive manufacturing embedded into a headset for spectral cue preservation and hearing protection. Before exploring these custom circumaural hearing devices, a study on the fabrication process of AM pinnae was performed. The KEMAR system for acoustic research was used as a benchmark for the 3D printed pinnae. The computer models of the KEMAR pinnae were obtained via 3D scanning and CT scanning. Material extrusion, vat photopolymerization and material jetting were the technologies used to carry out the manufacturing process. A selection of industrial and desktop equipment was done to perform an analysis on the printing resolution. Two different designs were used to place the AM pinnae onto the KEMAR. Six different pinnae were printed using three CAD files, and dimensional accuracy measurements were taken on all 3D printed pinnae using three different measurement tools, caliper, image processing software, and measurements from the CAD file derived from the CT scans of each pinna. These measurements were compared to the KEMAR pinna for fabrication evaluation. Results showed consistent measurements from the AM pinnae to KEMAR across the different sections of the pinna. An analysis of variance study was performed to find statistical differences between the baseline pinna and the AM pinnae, as well as AM pinnae among each other. Desktop printers were able to reproduce similar quality parts to the ones produced by the industrial equipment. This is an important determination, since cost will be an important factor when determining if, in the end, custom hearing protection devices can be printed at or near the point of need. Acoustic testing performed on two AM pinnae using the KEMAR system produced a similar frequency response to the one presented by the KEMAR pinnae. The replicas of the KEMAR pinna using additive manufacturing were successful. Even though the incorporation of an embedded pinna into a headset was designed but not tested, preliminary results on the acoustic analysis of the AM pinna motivates the development of AM custom hearing devices.
Acosta Carrasco, Carlos Felipe, "Additive Manufactured Ear Pinna for Spatial Cue Preservation in Custom Hearing Devices" (2019). ETD Collection for University of Texas, El Paso. AAI22618234.