Echo canceler and echo detector

An echo canceler for removing an echo component which is obtained by picking up a received signal with a microphone and is contained in a microphone input signal, the echo canceler comprising:

• a subband disassembling unit for splitting the received signal and the microphone input signal into subbands;
• a signal-to-echo ratio calculating unit for computing signal-to-echo ratios indicating ratios of the echo components to the received signal which is split into the subbands by the subband disassembling unit, from a combination of a first residual signal, a second residual signal and an update step size of an updated filter coefficient sequence,
• the first residual signal being obtained by filtering the microphone input signal using a filter coefficient sequence,
• the updated filter coefficient sequence being obtained by updating the filter coefficient sequence used for the first residual signal with the update step size,
• the second residual signal being obtained by filtering the microphone input signal using the updated filter coefficient sequence;
• an echo suppressing unit for generating output signals that undergo the suppression of the echo components contained in the microphone input signal which is split into the subbands in accordance with the signal-to-echo ratios the signal-to-echo ratio calculating unit computes;
• and
• a subband assembling unit for executing subband assembly of the output signals the echo suppressing unit generates for the individual subbands.

An echo detector for detecting an echo component which is obtained by picking up a received signal with a microphone and is contained in a microphone input signal, the echo detector comprising:

• a signal-to-echo ratio calculating unit for computing a signal-to-echo ratio that is a ratio of the echo component to the received signal from a combination of a first residual signal, a second residual signal, and an update step size of an updated filter coefficient sequence,
• the first residual signal being obtained by filtering the microphone input signal using a filter coefficient sequence,
• the updated filter coefficient sequence being obtained by updating the filter coefficient sequence used for the first residual signal with the update step size,
• the second residual signal being obtained by filtering the microphone input signal using the updated filter coefficient sequence;
• and
• an echo detecting unit for detecting the echo component in accordance with the signal-to-echo ratio the signal-to-echo ratio calculating unit computes.

An echo detector for detecting an echo component which is obtained by picking up a received signal with a microphone and is contained in a microphone input signal, the echo detector comprising:

• a subband disassembling unit for splitting the received signal and the microphone input signal into subbands;
• a signal-to-echo ratio calculating unit for determining signal-to-echo ratios indicating ratios of the echo components to the received signal which is split into the subbands by the subband disassembling unit, from a combination of a first residual signal, a second residual signal, and an update step size of an updated filter coefficient sequence,
• the first residual signal being obtained by filtering the microphone input signal using a filter coefficient sequence,
• the updated filter coefficient sequence being obtained by updating the filter coefficient sequence used for the first residual signal with the update step size,
• the second residual signal being obtained by filtering the microphone input signal using the updated filter coefficient sequence;
• and
• the echo detecting unit, referring to the signal-to-echo ratio for each subband the signal-to-echo ratio calculating unit determines, detects the echo component when an echo component not less than a prescribed threshold with respect to the received signal is present.