Having recently conducted a series of controlled latency and audio fidelity benchmarks on various noise-suppression stacks, I found myself with a rather practical, albeit niche, question that standard test vectors don't cover. We have ample data on steady-state noise like keyboard clicks, fan hum, and street traffic, but the transient, complex, and highly variable acoustic profile of mastication presents a fascinating edge case for any AI-driven audio pipeline.
The core technical challenge here is the convolutional nature of "snack noise." It's not a simple background layer; it's a series of impulsive, broadband events that occur in extremely close proximity to the vocal source—the mouth. The AI model must perform a real-time spectral decomposition to disentangle the harmonic and formant structures of speech from the chaotic, damped resonances of a cracker being crushed. This is a significantly harder problem than isolating a voice from a spatially separated noise source.
To approach this empirically, I devised a simple but methodical test protocol:
* **Test Corpus:** Recordings of standardized speech (TIMIT excerpts) mixed with calibrated samples of:
* Crunchy foods (potato chips, raw vegetables)
* Soft/moist foods (banana, sandwich bread)
* Packet rustling (opening a bag of chips)
* **Control:** A clean vocal track, and the noise samples alone.
* **Processing Chain:** The mixed audio was passed through Krisp (latest desktop client, "Max" suppression setting) in real-time simulation, and the output was captured.
* **Analysis:** Manual listening tests coupled with spectral analysis (FFT spectrograms) to visualize residual noise and potential speech distortion.
**Preliminary Findings:**
The performance is highly dependent on the acoustic profile of the snack and the speaker's discipline.
1. **For dry, high-frequency crunches (e.g., chips):** Krisp is remarkably effective at suppression, but not perfect. Approximately 85-90% of the peak transient energy is removed. However, the very sharpest attack of the crunch (the initial fracture) can sometimes bleed through as a faint, damped click. The subsequent speech is notably clean.
2. **For low-frequency, muffled chewing:** Suppression is near-total. The model seems to classify this as a non-vocal, low-priority noise and eliminates it almost entirely.
3. **The critical failure mode:** Concurrent speech and crunching. If you attempt to speak *while* the crunch event is occurring, the model faces a classic trade-off. In its attempt to suppress the broadband crunch, it often applies excessive attenuation to the coincident speech frequencies, resulting in a momentary "ducking" or muffling of the voice. This is observable in the spectrogram as a temporary notch in the speech formants.
4. **Packet rustling,** being a more diffuse, non-mouth noise, is suppressed with near-100% efficacy, as expected.
**Conclusion:** Krisp's voice detection during snack consumption is accurate in terms of *preserving* the isolated voice signal after the fact. However, the system's aggressiveness in eliminating the closely coupled noise can lead to minor, milliseconds-long artifacts on the speech signal itself during overlap periods. For optimal meeting performance, the micro-optimization is clear: employ a push-to-talk mechanism or, at the very least, adopt a chewing cadence that pauses during speech utterances. The latency introduced by the processing itself is negligible (sub-20ms on a modern CPU), so the bottleneck is purely the algorithmic discrimination of two spectrally mixed sources from the same point in space.
Good point about the proximity problem. Most models are trained on noise sources that are farther from the mic, like a separate keyboard. Your snack is right at the vocal source.
I've seen similar issues with breath pops and heavy plosives. The AI often misclassifies them as noise and clips the start of your speech. With crunching, it's likely either cutting your voice off or letting the crunch through.
Your test corpus idea is solid. Need to add variable mic placements in the protocol. A headset mic versus a laptop mic will give wildly different results because of the input signal's signal-to-noise ratio.
slow pipelines make me cranky