Ellipsoidal line cut system and method for hearing aid shell design

A system for trimming a hearing aid shell, comprising:

• a computer system having a processor, user input device, user display device, data storage device, and communications device;
• a line cut algorithm for establishing a line cut plane in a 3D model of an original hearing aid shell design that is not parallel to a bottom cut plane of the hearing aid shell;
• a contour algorithm for determining a projected contour on the bottom cut plane that corresponds in shape to a portion of the line cut plane contour;
• a merger algorithm for defining a line cut surface between the portion of the line cut plane contour and the projected contour, identifying a first portion of the hearing aid shell on one side of the line cut surface as a keep portion of the hearing aid shell, and second portion of the hearing aid shell on the other side of the line cut surface as a removal portion of the hearing aid shell, a new hearing aid shell design being defined by the keep portion of the hearing aid shell;
• and
• an elimination algorithm for eliminating parts of the new hearing aid shell design that extend beyond boundaries defined by the original hearing aid shell design.

A hearing aid shell, comprising:

• a shell surface and one portion of the surface being a line cut surface comprising a border contour divided into a first contour portion and a second contour portion, the first and second contour portions completely defining the border contour, wherein:
• the first contour portion has a first bent shape derived from an intersection of the shell and a line cut plane;
• and
• the second contour portion has a second bent shape lying in a bottom cut surface that is not parallel to the line cut surface and which is derived from an intersection of the shell and a bottom cut plane, the second bent shape being derived from a projection of the first contour portion onto the bottom cut plane which is flattened out to make it less bent so that the second bent shape is less bent than the first bent shape.

A computer readable media which designs a hearing aid shell, said media having a computer program which performs the steps of:

• producing a 3D data definition of an original hearing aid shell design;
• establishing a line cut plane that is not parallel to a bottom cut plane, thereby defining a line cut plane contour by an intersection of the line cut plane and the hearing aid shell;
• creating a projected contour on the bottom cut plane that corresponds in shape to a portion of the line cut plane contour;
• defining a line cut surface between the portion of the line cut plane contour and the projected contour;
• identifying a first portion of the hearing aid shell on one side of the line cut surface as a keep portion of the hearing aid shell, and second portion of the hearing aid shell on the other side of the line cut surface as a removal portion of the hearing aid shell, a new hearing aid shell design being defined by the keep portion of the hearing aid shell;
• eliminating parts of the new hearing aid shell design that extend beyond boundaries defined by the original hearing aid shell design;
• and
• producing the hearing aid shell design which is used to manufacture to the hearing aid shell.