---
title: "Decibel (dB)"
description: "The decibel (dB) is a logarithmic unit used to express the ratio between two values of an acoustic quantity — most commonly sound pressure, sound intensity or sound power. A 10 dB increase represents a tenfold increase in intensity and a perceived roughly doubled loudness. A 3 dB increase represents a doubling of intensity."
canonical_url: "https://sylio.co/glossary/decibel"
last_updated: "2026-06-28T02:29:23.255Z"
---

The **decibel (dB)** is a logarithmic unit used to express the ratio between two values of an acoustic quantity — most commonly sound pressure, sound intensity or sound power. A 10 dB increase represents a tenfold increase in intensity and a perceived roughly doubled loudness. A 3 dB increase represents a doubling of intensity.

## Why a logarithmic scale

Human hearing — and the practical range of industrial acoustic cleaning — spans more than ten orders of magnitude of sound pressure (20 µPa to several hundred Pa). A linear scale would be unwieldy. The logarithmic decibel compresses this into a tractable 0–180 dB band and aligns with how the ear actually responds to intensity changes.

## Reference points

<table>
<thead>
  <tr>
    <th>
      Value
    </th>
    
    <th>
      Meaning
    </th>
  </tr>
</thead>

<tbody>
  <tr>
    <td>
      +3 dB
    </td>
    
    <td>
      Sound intensity doubled
    </td>
  </tr>
  
  <tr>
    <td>
      +10 dB
    </td>
    
    <td>
      Sound intensity ×10; perceived loudness roughly doubled
    </td>
  </tr>
  
  <tr>
    <td>
      +20 dB
    </td>
    
    <td>
      Sound intensity ×100
    </td>
  </tr>
  
  <tr>
    <td>
      0 dB SPL
    </td>
    
    <td>
      Reference threshold of hearing (20 µPa)
    </td>
  </tr>
  
  <tr>
    <td>
      140 dB SPL
    </td>
    
    <td>
      Lower end of industrial <a href="/glossary/sonic-horn">
        sonic horn
      </a>
      
       output
    </td>
  </tr>
  
  <tr>
    <td>
      180 dB SPL
    </td>
    
    <td>
      Upper end of pneumatic industrial cleaning horns
    </td>
  </tr>
</tbody>
</table>

## Weighting

For noise-exposure work, raw dB is often weighted to better reflect human hearing. A-weighting (dBA) is the standard for occupational-noise calculations under [OSHA 29 CFR 1910.95](/glossary/osha-29-cfr-1910-95) and [EU Directive 2003/10/EC](/glossary/eu-directive-2003-10-ec). C-weighting (dBC) is used for peak exposure to high-level impulsive sound.

## Related terms

- [Sound pressure level](/glossary/sound-pressure-level)
- [Frequency](/glossary/frequency)
- [Octave band](/glossary/octave-band)