Do Earplugs Help You Focus? Not Against Voices Alone

In 1998, two researchers played the same background speech to people doing a memory task, once at 75 dB(A) and once at 60 dB(A). Fifteen decibels is a big drop. It made no difference. Wolfgang Ellermeier and Jürgen Hellbrück found the disruption was the same at both levels.

That result explains why earplugs disappoint in open offices. A plug makes voices quieter, but quieter is not what protects focus. Hard to understand is.

• 75 → 60 dBQuieter background speech, with the same damage to recallEllermeier & Hellbrück, 1998
• STI 0.44Speech clarity at which the performance drop reaches its maximumHaapakangas et al., 2020
• +5 dBAll that a second protector adds when you wear plugs under muffsOSHA Technical Manual

Volume is the wrong dial

A second experiment in the same paper points to the fix. Instead of lowering the speech, the researchers added pink noise. Performance improved in a straight line as the speech-to-noise ratio fell. Speech buried in steady sound stops grabbing attention, even at the same loudness.

Acoustics researchers have since built this into a model. Valtteri Hongisto's 2005 paper states it plainly: the sound level of speech does not decide how distracting it is. Its intelligibility does. Intelligibility is measured with the Speech Transmission Index (STI), which runs from 0 (nothing understood) to 1 (perfectly clear).

Half-heard speech does nearly full damage

The 2020 revision of that model pooled 34 tests from 14 laboratory studies. Haapakangas, Hongisto and Liebl found that performance starts to drop above roughly STI 0.21 and hits its maximum decline at STI 0.44. Here is what those numbers mean in conversation terms, using the IEC 60268-16 rating bands as summarized on Wikipedia:

Lining the two up is our synthesis, not a finding from either source, and it is uncomfortable. Speech rated only "poor" still delivers about nine sentences in ten, and that already does the full damage. If you can follow the conversation next to you, trimming its clarity a little won't help.

What an earplug changes, and what it leaves alone

A plug turns everything down together: the voices, the hum and the clatter. A 2024 paper in Trends in Hearing describes the baseline expectation for a device that both speech and noise pass through: the signal-to-noise ratio at the ear is not altered. For focus, that ratio is the number that matters.

Our reading, an inference rather than a tested result: in a quiet room, a well-fitted plug can push far-off speech below the point where you can make it out. That is where plugs alone work. In a café or open-plan office the voices stay audible and the ratio doesn't move. Doubling up won't rescue it: OSHA credits plugs under muffs with only 5 dB more than the better of the two.

Match the fix to the room

The headphone row follows Soundcore's own explainer: noise cancelling handles low-frequency hum better than voices, which change too fast to counter. ANC softens a coworker. It doesn't erase them.

Build the stack in four moves

1. Step 1: Block first

   Use a plug or noise-cancelling headphones to take the room down. Foam only reaches its rating if you roll it tight, insert it deep and hold it while it expands. The Mack's Ultra Soft foam plugs are the cheap way to learn whether quiet helps you.

2. Step 2: Mask second

   Add steady, wordless sound such as rain, a fan or pink noise. With the voices already lower, the masking can run quieter. Headphones with built-in soundscapes, like the Soundcore Space 2, do both jobs in one device.

3. Step 3: Run the words test

   Listen for ten seconds. If you can still follow what the nearest person is saying, you are in the zone that costs you. Raise the masking a notch or move seats, and keep it below the volume you'd use for music.

4. Step 4: Give the quiet an end

   Set a timer you can see and work until it rings. The Brain Deck pairs this with Card 13, The Visual Timer, so a sealed-off block feels like a sprint, not a sentence. A time box works the same way.

Where this breaks down

• Lab tasks, not workdays. Ellermeier and Hellbrück measured serial recall, which means remembering items in order, in short sessions.
• Noise has a cost in a quiet room. As our brown vs pink noise guide covers, steady noise slightly hurt lab performance in people without ADHD symptoms. Mask speech, not silence.
• Music is not masking. Lyrics are speech too, which our music and focus guide explains.

Earplugs and focus FAQ

Why can I still hear coworkers through noise-cancelling headphones?

Noise cancelling is built for steady, low-pitched sound. Voices change too quickly for it to counter fully, so it softens them rather than removing them. Low, steady sound played through the headphones covers what the cancelling misses.

Is a higher NRR better for concentration?

Only up to a point. Fit changes real-world blocking more than a few decibels on the label, and loudness isn't the main lever for speech. Our focus earplugs and headphones guide explains the ratings.