There's a reason you can ignore the hum of an air conditioner but not the person on the phone three desks away.
Your brain processes speech involuntarily. When you hear intelligible words — even fragments of a conversation you're not part of — your language centers activate automatically. You can't choose to not decode them. It's hardwired.
This is why speech is the most disruptive sound type in open offices, coworking spaces, and work-from-home environments. Not the loudest. The most disruptive. There's a difference.
Most white noise covers a broad frequency range. That's fine for general masking. But it's inefficient for speech specifically, because human voice intelligibility is concentrated in a relatively narrow band.
The core speech frequency range is 300 Hz to 3,000 Hz. This is where the fundamental frequencies of adult speech and the most important formant frequencies (the resonances that make vowels distinguishable) live. If you can mask this range effectively, speech becomes unintelligible background noise — like hearing a conversation through a wall.
Quilence's Speech Blocker preset is specifically tuned for this.
Instead of boosting all frequencies equally, Speech Blocker concentrates energy in the 250 Hz–2 kHz range where speech intelligibility lives. It uses white noise as the base (for its broad-spectrum coverage) and shapes the EQ to create a focused mask:
- 250 Hz: Boosted to cover the lower range of male speech
- 500 Hz: Boosted — the fundamental frequency range for most adult voices
- 1 kHz: Highest boost — this is where vowel formants are most dense
- 2 kHz: Moderate boost for upper speech clarity
- Frequencies above and below the speech range are reduced, so you're not wasting energy masking sounds that aren't there
The result is a more effective speech mask at a lower overall volume than generic white noise.
Practical tips:
Pair it with noise-cancelling headphones. ANC handles the low-frequency rumble (HVAC, traffic). Speech Blocker handles the mid-range conversation. Together they cover the full spectrum.
Don't crank it up. The preset works at moderate volumes. If you can't hear your own thoughts, it's too loud. The goal is to make speech unintelligible, not to overpower it.
Use the 10-band EQ to fine-tune. Every office is different. If your main distraction is a deep male voice, boost 250 Hz. Higher-pitched voice? Push 2 kHz up. The preset is a starting point.
Set up Focus Mode integration so Speech Blocker starts automatically when you enter Work Focus. One less thing to think about.
The research backs this up. Studies consistently show that intelligible speech is more disruptive to cognitive performance than unintelligible speech, random noise, or even louder non-speech sounds. The key word is intelligible. Once you make the speech unintelligible through frequency-targeted masking, it loses most of its disruptive power.
That's what Speech Blocker does. It doesn't silence the office. It makes the conversation disappear into the background.