When we talk about the noise emitted by a PC component, or even to express the sound power of any audio system, in this world of hardware it is much more use than Sone dBA. In this article we are going to explain why it is done this way and what each of these magnitudes means.
Of course, it is de rigueur that before we tell you why one magnitude is used and not the other, we explain what each one is so that you can properly understand its magnitude and its use, so let’s start at the beginning.
dBA and Sone, what are they and how are they measured?
The dB (decibels) is a unit of acoustic pressure, and therefore it is a measure of force , more specifically the acoustic force per unit of area. Every time the measured distance is doubled, 6 dB is “lost”. A given sound pressure level without the measurement distance to the source is therefore useless, it is useless, except to compare two measurements taken with the same objective. The usual thing, if nothing is said, is to take the measurement in dB at 50 cm from the sound origin.
The human ear does not respond the same to all frequencies: we are much more sensitive to sounds in the frequency range between 1 and 5 KHz than to very low or high frequency sounds. For this reason, sound meters are generally equipped with a filter whose frequency response is similar to that of the human ear. If this “A-weighting filter” is used, the sound pressure level is given in units of dB (A) or directly known dBA .
Finally, the universal loudness unit is the Sone. In acoustics, volume is a subjective measure of sound pressure. The number of Sones was chosen based on the noise emitted by a telephone so that doubling its volume would double the number of Sones. So this is an arbitrary measure for noise with a linear and non-logarithmic arithmetic scale, as in dB.
Of course, both magnitudes are to some extent subjective but also equivalent. Below you can find the table of equivalence between one and the other (remember that 1 Sone is equivalent to the noise a telephone makes when ringing to have it as a reference).
| Sone | dBA |
|---|---|
| 0.2 | 21 ~ 21.5 |
| 0.3 | 22.5 ~ 24.5 |
| 0.4 | 23.5 ~ 25 |
| 0.5 | 25 ~ 26 |
| 0.6 | 25.5 ~ 27 |
| 0.7 | 28 ~ 29 |
| 0.8 | 28.5 ~ 29.5 |
| 0.9 | 30 |
| 1.1 | 31 |
| 1.2 | 30.5 ~ 33 |
| 1.3 | 32 ~ 34 |
| 1.4 | 33 |
| 1.5 | 32.5 ~ 35 |
| 1.6 | 33 ~ 35 |
| 1.7 | 3. 4 |
| 1.8 | 33.4 ~ 36 |
| 1.9 | 35.5 ~ 36 |
| 2.0 | 37.5 |
| 2.1 | 38 |
| 2.2 | 35.5 |
| 2.3 | 38 ~ 39 |
| 2.4 | 38 ~ 40 |
| 2.5 | 38.8 |
| 2.6 | 39 ~ 40 |
| 2.8 | 40 |
| 3.0 | 40 |
| 3.1 | 44.5 |
| 3.9 | 45 ~ 46 |
If this doesn’t tell you much either, let’s see the subjective noise values, in this case in dB SPL.
| dB | Example |
|---|---|
| 140 | An airplane taking off, 30 meters away |
| 130 | Pain threshold |
| 120 | Discomfort threshold |
| 110 | Chainsaw one meter away |
| 100 | Disco within 1 meter of speakers |
| 90 | Truck 10 meters away |
| 80 | Noisy and busy street |
| 70 | Vacuum cleaner 1 meter away |
| 60 | Speech 1 meter away |
| fifty | Average noise of a home |
| 40 | Silent library |
| 30 | Bedroom at night |
| twenty | Background noise in a recording studio |
| 10 | A leaf falling in the wind |
| 0 | Hearing threshold |
Why are dBAs used to measure noise from a PC?
It is not very well known who or when made the decision that the noise emitted by the PC components would be expressed in dBA and not in any of the other magnitudes, but the fact is that this is the case for several reasons, and the most important of They are because it is a very easy quantity to measure, since as we have explained before in the dBA, filters are used that limit the capture frequencies, so it is very easy to do a weighting to calculate the value.
The second reason is that dBAs have a much more exact scale than Sone. Although they are also easy to measure, Sones are much more subjective, while as you may have already noticed in the equivalence table that we put above, dBAs have a much larger spectrum of levels and, in addition, they admit decimals.