Why Does a Local Voice Assistant Interrupt Itself in a Reverberant Room?
A local voice assistant can interrupt itself when reflected playback survives echo cancellation and is mistaken for a wake word or human barge-in signal.
The assistantโs speaker and microphones share the same room, so every spoken response returns through direct leakage and delayed reflections from walls, furniture, and glass. Acoustic echo cancellation estimates that path and subtracts playback from the microphone stream. Long reverberation, device movement, nonlinear speakers, volume changes, and simultaneous human speech make the estimate incomplete and can trigger interruption logic.
Playback Returns Through a Time-Varying Echo Path
The microphone captures near-end speech plus the assistantโs loudspeaker signal convolved with the room impulse response. A short direct path is easier to model than hundreds of milliseconds of decaying reflections, especially when people or objects move.
reverberated playback echo removes text-to-speech playback echo from overlapping recordings and explicitly models reverberated TTS captured by the microphone. The problem formulation shows why the assistant has a clean reference signal yet still receives a transformed acoustic copy.
An adaptive filter continually estimates the echo path from playback reference to microphone. If its filter is too short, adapts too slowly, or resets between responses, residual speech can retain enough phonetic structure to resemble the wake word or a barge-in utterance.
Double-Talk and Nonlinear Playback Limit Cancellation
During double-talk, a person speaks while the assistant is playing audio. The canceller must preserve the human voice without adapting to it as if it were part of the echo path; aggressive suppression can erase the user, while weak suppression leaves self-speech.
nonlinear residual echo combines an adaptive filter with a deep network across several stages to handle residual echo and nonlinear components. The architecture reflects that linear subtraction alone cannot model loudspeaker distortion, clipping, and room effects under every condition.
Volume-dependent speaker distortion is especially troublesome because the playback reference is captured before the amplifier and transducer add nonlinearities. Moving the device, covering a microphone, or changing output routing also invalidates a previously converged filter.
Wake-Word and Barge-In Logic Convert Residual Echo Into an Action
After echo suppression, voice activity and wake-word models decide whether a person is speaking. Low thresholds improve responsiveness but can interpret residual syllables, reverberant tails, or comfort-noise artifacts as evidence to stop playback and reopen recognition.
joint speech and echo processing develops real-time personalized speech enhancement with acoustic echo cancellation under strict compute limits. The work highlights the need to preserve target speech while suppressing simultaneous playback rather than treating the whole mixed interval as noise.
The failure boundary is assuming interruption proves poor echo cancellation. An actual user, television, notification sound, or network-delayed control event can stop playback too. Log residual-echo metrics, wake confidence, voice activity, and the final interrupt decision on the same clock.
Measure Self-Interruption Against the Playback Reference
Play fixed assistant phrases at several volumes in a quiet room, then add a human barge-in, television speech, and device movement. Test near and far microphone positions while recording playback reference, raw microphones, echo-cancelled audio, wake scores, voice activity, and interrupt timestamps.
Compare the room variables with far-field voice limits. Measure echo return loss enhancement, false interrupts per hour, missed real barge-ins, and recovery time after the echo path changes rather than judging only how clean recordings sound.
Tune the interrupt threshold only after the canceller converges under representative rooms and volumes. If suppressing self-echo also removes real users, require a longer confirmation window or directional evidence instead of maximizing either cancellation or responsiveness alone.
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