Volume is not a well defined measure in terms of audio or sound. Decibels (dB) are what define it proportionally, in terms of physics.
Imagine you have two audio signals and signal 1 is ten times stronger than signal 2, you can say that it is 10 dB stronger. If so, signal 1 is stronger 20 dB and if signal 2 is weaker with -20dB. This is calculated using a logarithmic formula.
So the sound pressure levels (SPL) in dB refer to 20 milli pascals (mPa) at 0 dB, which is actually the hearing threshold level in absolute vacuum.
This is where the proportion comes into play. I will use this example to make it easier to understand and not so mathematical and physics terms. Imagine that we are listening to our headphones in a quiet place. Let’s say that decibel level environment in our hearing aids is 80. Now it occurs to us to go for a walk obviously with the headphones on, and we find that our neighbor is mowing the lawn with a brush cutter (machine that has an engine and uses gasoline to mow the lawn). When we enter that medium, the headphones are at 80 dB. So how do you measure when we enter that medium?
As I said a decibel (dB) is a proportion, which is based on a base level. In the first case I said was in absolute silence. And in the second example with the sound of the lawnmower. Then in the second example our ears are listening to the decibel level of the lawn mower according to the decibel level of our hearing aids. Then we could increase the volume of our hearing aids beyond the lawn mower until we reach 130 dB to continue listening to our clearly and very loudly what is being played in our hearing aids. According to OSHA, 130 dB is where the ear pain threshold begins.
What does decibel and frequency mean?
Decibels (dB) and frequency are terms used to describe the sound levels and the number of cycles of a sound wave in a second.
To get a clear idea of the technical words that describe the facts about hearing impairment and noise, we have compiled the basic data on dB and frequency.
Frequency
The frequency of a sound is the number of cycles of a sound wave in a second. The unit of measurement is hertz (Hz). The frequency of a sound increases as the number of cycles per second increases. Vibrations between 20 and 20,000 cycles per second are interpreted as the sound a healthy person hears. A high pitched sound could be a piccolo or the song of a bird. The bass sounds could be the sound of distant thunder or the tones of a bass.
Decibel (dB)
The term dB (decibel) and the dB scale are used worldwide to measure sound levels. The decibel scale is a logarithmic scale in which twice the sound pressure corresponds to an increase in the level of 6 dB.
It is very important to understand that the term ‘dB’ can have different meanings and that it is not a fixed value such as volt or meter, etc. The value of a dB depends on the context in which it is used.
Below you will find examples of different sound intensities expressed in dB (HL):
180 dB: Rocket on takeoff
140 dB: Engine of a jet plane when taking off
120 dB: Rock band
110 dB: Strong thunder
90 dB: Traffic in the city
80 dB: The radio at a high volume
60 dB: Normal conversation
30 dB: Soft whisper
0 dB: The lowest sound that a person perceives
