Device and method for interpolating frequency components of signal adaptively

A frequency interpolating device for receiving an input signal obtained by suppressing frequency components in a particular frequency band of a given original signal to narrow an entire frequency bandwidth of the original signal and recovering a signal similar to the original signal by approximately creating the suppressed frequency components, the frequency interpolating device comprising:

• means for creating an interpolation signal having frequency components in said suppressed band, by frequency-converting frequency components in a residual frequency band of said input signal;
• means for spectrum-analyzing said input signal to extract a spectrum pattern;
• comparing means for comparing said extracted spectrum pattern with a plurality of reference spectrum patterns registered beforehand, and on the basis of a comparison result to select an addition level of said created interpolation signal relative to said input signal;
• and
• means for adding said created interpolation signal to said input signal at said selected addition level, wherein said comparing means includes a look-up data table storing data representative of a correspondence between said reference spectrum patterns and said addition levels, said look-up data table being created on the basis of an auditory test of a plurality of acoustic signal samples,
• wherein said means for extracting the spectrum pattern of said input signal operates to output a code corresponding to said extracted spectrum pattern, and said comparing means is made of a memory that stores data representative of a correspondence between said reference spectrum patterns and said addition levels, and
• wherein said code is inputted to said memory as a memory address to output the addition level stored at a memory location indicated by the memory address designated by said code.