It is highly precisely determined as to whether or not a laser-irradiated position on an optical disk is positioned within an identification area in which identification information is recorded, and the position of the identification information area is efficiently determined. An example apparatus includes a sense amplifier circuit configured to be coupled to a digit line and configured to, during a memory access operation, drive the digit line to a voltage that indicates the logical value of the charge stored by a memory cell coupled to the digit line. Intermediate structures formed during fabrication of an earth-boring tool include green bodies having a plurality of hard particles, a plurality of matrix particles comprising a metal matrix material, and an organic material that includes a long chain fatty acid derivative. Operation of the headset is modified based on the donned or doffed status of the earbuds. Further, the wobble detection circuit changes a gain for amplifying the signal in a wobble signal detection process depending on the pre-format of a reproducing or recording medium to obtain a wobble signal.