Hi, I wish I had them. Trust me, I searched whatever came to my mind for a few days before I sent this question. Recording the sound with a smart phone, analyzing the audio signal, determining a frequency of around 2 kHz, generating the mesh of a tea cup/mug but missing the handle, using FEM to determine the modes. In general making nice use of various Mathematica features.

Dear Tim, thank you very much for the reply. That is exactly the contribution, I was looking for. I had a look at a number of your very nice contributions on your website (?) but at that time I had found them while tackling an entirely different issue. Unluckily, I did not jot down your URL. Greetings Ernst