The notion of range is used with reference to the amplitude of a phenomenon, taking into account the variation that occurs between a lower limit and an upper limit . Audible , meanwhile, is that which can be perceived with the ear (that is, that is heard).
The idea of audible range , in this framework, refers to all the frequencies that the ear of a human being is able to perceive . Also known as the audible spectrum , audible sound or tone field , it is a margin that, beyond generalities, varies in each individual and even undergoes changes with age.
In a broad sense, it can be stated that a young person with healthy hearing has an audible range between 20 hertz ( Hz ) and 20 kilohertz ( kHz ). Therefore, any sound emitted between those frequencies can be heard by the subject.
When the acoustic wave has a frequency lower than 20 Hz , it is called infrasound . On the other hand, if the frequency of the acoustic wave exceeds 20 kHz , it is an ultrasound . In neither case is the sound perceived by the human ear since it is located outside the audible range.
It is important to keep in mind that the audible range does not only decrease with the passage of time . If someone is exposed to very loud sounds, they can suffer serious damage to their hearing system, thereby affecting the width of the audible range. Therefore, those who carry out work activities in which intense noises are generated must protect their ears to avoid injuries.
When the audible range is affected by the passage of time, we speak of presbycusis , which is defined as hearing loss that occurs progressively and that mainly affects high frequencies, starting with the range between 500 and 4000 hertz, which is generally associated with speech. The aging of the auditory nerve and the inner ear are the main reasons for this practically inevitable deterioration that we go through in old age.
During youth, and as long as there are no health problems related to hearing, our audible range is equivalent to ten octaves. In the field of music, we call the interval comprising eight degrees of a musical scale an octave; Although there are several types, in a few words we can say that on a piano an octave is the space between two keys of the same name (for example, "from C to C").
Continuing with the concept of octave, the audible range of the human being can be divided taking into account the tones covered by each group: the first four octaves are equivalent to low tones , with frequencies between 16 and 256 hertz; The next three are the midtones , whose frequencies are between 256 and 2000 hertz; From there and up to 16,000 hertz are the high tones , which extend throughout the last three octaves.
We often find confusion between the concepts audio frequency and radio frequency : while the first refers to mechanical waves (they cannot propagate in a vacuum), the second represents electromagnetic waves (they can propagate).
The audible range of humans , on the other hand, is different from the audible range of animals . Elephants , for example, hear infrasound , while bats detect ultrasound .
Another aspect to consider is that, beyond frequency, what the human ear perceives depends on the acoustic intensity . Sounds between 0 and 130 decibels ( dB ) can be captured, although those that exceed 90 dB are harmful.