1. A method for processing a signal, the method comprising: receiving, by an audio coding apparatus, an encoded entropy table index and one or more pilot difference values; entropy-decoding the encoded entropy table index; identifying, from among multiple entropy tables used for decoding the pilot difference values, a particular entropy table using the entropy table index; entropy-decoding the pilot difference values using the particular entropy table; and obtaining data elements using a pilot reference value and the entropy-decoded pilot difference values, wherein the entropy table index is entropy decoded using an entropy table which is reserved exclusively for entropy table indexes.