Your mention of sim b'aznei made me think of the fact that Hamantashen in Hebrew are ozney Haman. Perhaps the name implies a hint as to what one hears. We hear the megillah; we said at kabbalas haTorah na'ase venishma. As a part of the body, the ear could also stand in for the slave status that Haman had based on the Midrash that he sold himself to Mordechai for bread.I can't resist getting the last word in, so I would just add the following: Amalek failed to respond to what their ears heard in the same way as other nations did – “sham’u amim yirgazun”. The parsha of Amalek is followed by the immediate contrast of “vayishma Yisro”, and it was the Keini descendents of Yisro who Shaul warned away before battling Amalek of his time.
But focussing more directly on “ozen”: Maharal (Be’er haGolah ch. 3, see also Ch Aggados to Kesubos 5) has an interesting comment about the ear. Every sense organ has a covering – eye lids, mouth can be closed, a nose can be pinched closed. The ear is always open – it is the ultimate kli kibul. A kli kibul has no identity of its own but is made by what is placed inside, and to a certain degree, it is this quality of being a kli kibul which makes us human. We absorb and assimilate into our thinking and personality that which we take in from the outside world. A cherish is patur from mitzvos because without the kli bibul of hearing, he/she is lacking in identity.
We are what we hear, and whether we fill our ears with the dvar Hashem or with havalei olam hazeh determines whether we are in the reshus of Amalek or following Hashem.
Chochmas Adam ta’ir panav. All the other sense organs – eyes, nose, mouth – are located in the front of the face with the exception of the ears. The defeat of Amalek is not through chochma, through the direct experience of “panim”, but through hisbatlus, ad d’lo yada.
Divrei Chachamim b’Nachas Nishma’im. The gematriya of ozen is 58, the same as the gematriya of chein. R’ Nachman m’Breslev (Lik Moharan #1) explains that chein must make an impression, which is indicated by the letter “taf” added to “nach” (to spell “nachas”), as used in the pasuk “v’hisvisa tav” (Yechezkel 9), making a mark. The “chein” or “ozen” is the kli kibul for divrei chachamim, but words are only effective to the degree that they impact the listener.
And of course, the gematriya of 58 matches noach, prominently featured in the pesukim about "nachu mei'oyveihem".
“Sim b’aznei Yeshoshua” is the charge to create an impact upon Yehoshua, to ensure that he is a kli kibul which will carry the message of mechiyas Amalek l’dor dor.