Decibels explained: What does it actually mean?

With decibels, you decide how loud you want to play it. That’s true, but it imprecise and not the entire truth. If you want to really explain how sound volume then things get a little more complicated. Read on as decibels are explained.

Why we use decibels

What we perceive auditory are changes in air and sound pressure. This is why the term sound pressure level is often used in connection with volume – and the sound pressure is measured in the unit Pascal. Why do we not find any Pascal but decibel values in the audio range?

The fact that the correlations in volume data are somewhat more complicated is due to the human hearing. The perceptible changes in sound pressure lie in a range between 0.00002 Pascal and 20 Pascal. Range, therefore, extends over several orders of magnitude (number of digits for numbers). If the sound pressure level is low, we can already perceive small changes in air pressure, but at higher levels, the changes in air pressure must be significantly greater in order to be perceptible.

With a linear scale, this could not really be shown in a meaningful way, because differences would not be visible at low levels. Therefore decibels are used as logarithmic auxiliary units. With a logarithmic scale, the values are increased tenfold at defined intervals. Thus, a zero is added to each value on the scale. If this is visualized in a curve, it does not rise constantly but becomes steeper and steeper as the curve progresses.

Decibel on the ears – headphones at Teufel

The Decibel table: sound and their dB

In order to be able to correctly classify volume data in decibels, one must know that doubling the dB value does not mean doubling the sound pressure level. A chainsaw with a volume of 120 dB produces a much higher sound pressure level than an average conversation with 60 dB. A doubling results from an increase from 50 to 60 decibels. At a volume of 120 dB, the pain threshold for the human ear is reached. We then inevitably cover our ears and damage to our hearing can occur after a short time.

This table shows different sound events and the corresponding decibel value:

Sound measurement dB
Quiet breathing10
Light wind, whispering30
Cars from a short distance90
Headphones on loud95
Stereo speaker100
Jet aircraft from close range140

Note on dBFS

In the HiFi range, it is more common for amplifiers to display negative dB values. This is usually the unit dBFS (decibels relative to full scale). This scale is used in digital signal processing. The zero corresponds to the highest achievable value, accordingly, other values are displayed in the minus range.

What also makes the perception of volume different

One can dive even deeper into the topic. The pure sound pressure level does not take into account an important characteristic of the human hearing when perceiving volume. The intensity with which a certain sound pressure level is perceived depends on the height or frequency of the sound. In order to come close to the perceived volume of a sound, frequency-dependent weighting filters were introduced for decibels. These are sometimes given in brackets: dB(A). In addition, there are psycho-acoustic units such as phone and sone, which also take into account the frequency-dependent auditory impression.

In principle, the volume can only be quantified to a limited extent because perception varies greatly from person to person. While one might think that a well-maintained, turned-up system with 95 decibels is just right, for the other it can be much too much. In addition, even one and the same person can perceive volume quite differently depending on his or her condition. Stress, for example, has a great influence on perception.

Decibels that your ears love

Definion 3 Lautsprecher in der Nahaufnahme
The Definion 5.1 set achieves a maximum sound pressure level of 105 dB.
  • Ultima 40: The UItima 40 delivers precision sound over the entire frequency range and at high levels, inspiring even the most stringent sound critics. Two woofers with long strokes produce strong bass, while a newly developed phase plug for even more precise reproduction is used in the tweeter range. In addition, the stereo set is outstandingly processed and looks damn good – stereo at its best.
    Definion 3: the definition of high-end sound. The coax drivers for tweeters and mid-range drivers deliver sound like an almost point-shaped sound source. This avoids audible time differences and creates an absolutely natural sound space.
    ▶ Overview of our stereo loudspeakers.
    ▶ An overview of our sound systems.

A/V-Receivers in the Teufel shop

The most important facts summarised in decibels

  • Decibel is an auxiliary unit of measurement used to indicate the sound pressure level.
  • As a logarithmic scale, the dB scale is suitable for representing the sound pressure range audible to humans.
  • At 120 dB, the sound pressure reaches a level that we find unpleasant or even painful.
  • The perceived volume always depends on the frequency reproduced.
  • In order to take the frequency into account in volume data, so-called weighting filters and psychoacoustic parameters such as sone and phon were introduced.

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