US 12,406,678 B2
Sound signal purification using decoded monaural signals
Ryosuke Sugiura, Tokyo (JP); Takehiro Moriya, Tokyo (JP); and Yutaka Kamamoto, Tokyo (JP)
Assigned to NIPPON TELEGRAPH AND TELEPHONE CORPORATION, Tokyo (JP)
Appl. No. 18/032,792
Filed by NIPPON TELEGRAPH AND TELEPHONE CORPORATION, Tokyo (JP)
PCT Filed Nov. 5, 2020, PCT No. PCT/JP2020/041397
§ 371(c)(1), (2) Date Apr. 19, 2023,
PCT Pub. No. WO2022/097234, PCT Pub. Date May 12, 2022.
Prior Publication US 2023/0402044 A1, Dec. 14, 2023
Int. Cl. G10L 19/008 (2013.01); G10L 25/06 (2013.01); G10L 25/21 (2013.01)
CPC G10L 19/008 (2013.01) [G10L 25/06 (2013.01); G10L 25/21 (2013.01)] 13 Claims
OG exemplary drawing
 
1. A sound signal purification method for obtaining, for each frame, an n-th channel purified decoded sound signal  Xn that is a sound signal of each channel of stereo by using at least an n-th channel decoded sound signal  Xn (n is each integer of 1 or more and N or less) that is a decoded sound signal of the each channel of the stereo obtained by decoding a stereo code CS and a monaural decoded sound signal  XM that is a monaural decoded sound signal obtained by decoding a monaural code CM that is a code different from the stereo code CS, wherein
the n-th channel decoded sound signal  Xn is obtained by decoding the stereo code CS without using either information obtained by decoding the monaural code CM or the monaural code CM, and
the sound signal purification method further comprises
a monaural decoded sound upmixing step of obtaining, for the each frame, an n-th channel upmixed monaural decoded sound signal  XMn that is a signal obtained by upmixing the monaural decoded sound signal  XM for the each channel by an upmixing process using the monaural decoded sound signal  XM and inter-channel relationship information that is information indicating a relationship between the channels of the stereo, and
an n-th channel signal purification step of obtaining, for the each frame and for each corresponding sample t with respect to the each channel n, a sequence based on a value  xn (t)=(1−an)× xn(t)+αn× XMn(t) obtained by adding a value αn× XMn(t) obtained by multiplying an n-th channel purification weight αn by a sample value  xMn(t) of the n-th channel upmixed monaural decoded sound signal  XMn and a value (1−an)×  Xn (t) obtained by multiplying a value (1−an) obtained by subtracting the n-th channel purification weight αn from 1 by a sample value  Xn (t) of the n-th channel decoded sound signal  Xn, as the n-th channel purified decoded sound signal  Xn.