Speech encoding in a client server system such as a laptop, personal data assistant or mobile phone communicating with an interactive voice response telephony application. First and second portions of the electrically insulating layer extending opposite the first and second openings, respectively, are simultaneously etched at first and second different etch rates. It is particularly advantageous to form the tissue with chemimechanically treated fibers in at least one layer. The second device has a second surface including at least one second optically active area positioned in an opposed and spaced-apart relationship with respect to the at least one first optically active area. The sealing element has a holding element monolithically formed with the sealing element and captively securing the sealing element on the collar.