Modelling an ear is a little daunting because it is undoubtedly the part of the human body with the most characteristic details.
However it is not so complicated if broken down step by step
As usual a drawing allows to locate the details with for modelling
There are no two ears identical but they all have approximately the same characteristic details.
As usual, put the image on a rectangular face.
This time as for the head, one starts from a simple rectangular face starting from a shape Rectangle converted into Mesh.
Extrude the edge to form the circumference of the ear by selecting a edge and moving whilst holding the shift key.
Join the band together using Weld on the vertices
In the same way for the interior part.
Select two edges and extrude them.
Select the edges like on the left and perpendicularly extrude towards the interior, then make a uniform scale to make the additional sections smaller as shown.
Extrusion of the "slope", this part connects the external edge with my hollow part of the ear.
Extrude for the dimensions shown then adjust the vertecies to make the slope.
Build the faces marked in red with Create.
Do not forget to assign the smoothing group to 1.
Extrude these edges and weld the vertexes with Weld Target.
Finally build these faces.
The interior polygon will be used for the end to extrude the beginning of the auditory canal.
Fill the holes as opposite.
Apply Meshsmooth and make any additonal necessary vertex adjustments