A computer-implemented method which, when executed on data processing hardware, causes the data processing hardware to perform operations comprising: receiving a microphone signal comprising acoustic echo captured by a microphone, the acoustic echo corresponding to audio content played back from an acoustic speaker; receiving a reference signal comprising a sequence of frames representing the audio content transmitted in a reference channel before the acoustic speaker plays back the audio content; for each frame in a sequence of frames of the microphone signal: processing, using an acoustic echo canceler configured to receive a respective frame in the sequence of frames of the reference signal as input, the respective frame of the microphone signal to generate a respective output signal frame that cancels the acoustic echo from the respective frame of the microphone signal; and determining, using a Double-talk Detector, based on the respective frame of the reference signal and the respective output signal frame, whether the respective frame of the microphone signal comprises a double-talk frame or an echo-only frame, wherein determining whether the respective frame of the microphone signal comprises the double-talk frame or the echo-only frame comprises: computing, using the DTD, a respective first frame-level double-talk indicator based on a cross-correlation between the respective frame of the microphone signal and the respective frame of the reference signal; computing, using the DTD, a respective second frame-level double-talk indicator based on a cross-correlation between the respective frame of the microphone signal and the respective output signal frame; determining whether or not at least one of the respective first or second frame-level double-talk indicators (208a, 208b) satisfy a double-talk threshold; and when at least one of the respective first or second frame-level double-talk indicators (208a, 208b) satisfies the double talk threshold, determining the respective frame of the microphone signal comprises the double-talk frame; and for each respective frame in the sequence of frames of the microphone signal that comprises the echo-only frame, muting the respective output signal frame; and after muting the respective output signal frame for each respective frame in the sequence of frames of the microphone signal that comprises the echo-only frame, performing speech processing on the respective output signal frame for each respective frame in the sequence of frames of the microphone signal that comprises the double-talk frame. receiving a microphone signal comprising acoustic echo captured by a microphone, the acoustic echo corresponding to audio content played back from an acoustic speaker; receiving a reference signal comprising a sequence of frames representing the audio content transmitted in a reference channel before the acoustic speaker plays back the audio content; for each frame in a sequence of frames of the microphone signal: processing, using an acoustic echo canceler configured to receive a respective frame in the sequence of frames of the reference signal as input, the respective frame of the microphone signal to generate a respective output signal frame that cancels the acoustic echo from the respective frame of the microphone signal; and computing, using the DTD, a respective first frame-level double-talk indicator based on a cross-correlation between the respective frame of the microphone signal and the respective frame of the reference signal; computing, using the DTD, a respective second frame-level double-talk indicator based on a cross-correlation between the respective frame of the microphone signal and the respective output signal frame; determining whether or not at least one of the respective first or second frame-level double-talk indicators (208a, 208b) satisfy a double-talk threshold; and when at least one of the respective first or second frame-level double-talk indicators (208a, 208b) satisfies the double talk threshold, determining the respective frame of the microphone signal comprises the double-talk frame; and for each respective frame in the sequence of frames of the microphone signal that comprises the echo-only frame, muting the respective output signal frame; and after muting the respective output signal frame for each respective frame in the sequence of frames of the microphone signal that comprises the echo-only frame, performing speech processing on the respective output signal frame for each respective frame in the sequence of frames of the microphone signal that comprises the double-talk frame.