Method and apparatus for mathematically characterizing ear canal geometry

An apparatus for mathematically modeling a person's ear canal, the apparatus comprising:

• a housing including an aperture;
• an ultrasonic transducer array located within at least a portion of the housing, the housing adapted to position the ultrasonic transducer array on a person's skull outside of and surrounding a pinna, such that at least a portion of the pinna is within the aperture;
• electronics within the housing, the electronics adapted to control the transducer array to transmit ultrasonic energy at a first frequency and receive ultrasonic energy at a second frequency, wherein the second frequency is different than the first frequency, wherein the transducer array is configured for a frequency operating range dependent on a measured depth of the ear canal, wherein the depth of the ear canal is measured at least in part using the ultrasonic transducer array;
• and
• a processor within the housing, the processor configured to control each transducer in the transducer array and adapted to mathematically characterize geometry of the ear canal using information from the ultrasonic transducer array obtained from scans of the ear canal, wherein the mathematically characterized geometry of the ear canal is generated to create specifications for producing a hearing aid shell customized for at least a portion of the ear canal.