Obviousness

The provided patent text for US9070374B2 includes a "Prior art keywords" section listing "speech, unit, noise, microphone, signal." However, it does not provide a list of specific prior art documents (e.g., patents, publications) that would be necessary to perform a detailed obviousness analysis under 35 U.S.C. § 103 by combining specific references.

Without named prior art references, it is not possible to identify combinations of specific prior art and explain the motivation for combining them in the manner typically required for an obviousness analysis. The "Priority claimed from" documents (JP2012034189A and JP2012034192A) are priority documents, not typically considered prior art against US9070374B2 itself under normal circumstances.

Therefore, I cannot fulfill the request to identify combinations of prior art references and motivations for their combination, as the specific prior art documents are not provided within the "Prior Art" section or any other section of the given patent text.