A method and apparatus are provided for matching an output of an auxiliary signal transducer with a reference signal transducer where the auxiliary signal transducer and reference signal transducer receive audio signals from a common signal source along different respective signal paths. The compounds are generally fused-, spiro- or bridged-nitrogen heterocycles having an aryl and heteroaryl component and are useful in pharmaceutical compositions, methods for the treatment of CCR1-, CCR2- andor CCR3-mediated diseases, and as controls in assays for the identification of competitive receptor antagonists for the above chemokine receptors. A circularly polarizing unit, including a single linear polarizer plate, selectively passes either right handed or left handed circularly polarized light out of natural light. The first mirror layer has, in a region lying opposite the contact area of the contact structure, a cutout which is larger than the contact area of the contact structure. The CLV optical disc medium recordingreproducing apparatus can perform the seeking operation by use of the CPU and the other relevant units regardless of the operation of controlling the disc revolution number. Such compounds are MEK inhibitors and useful in the treatment of hyperproliferative diseases, such as cancer and inflammation, in mammals.