Sound sensation

The sound sensation is the perceptual characteristic of sound, which is directly linked to the concept of intensity, which means, the way in which the ear perceives intensity. The Weber-Dates law says that “the sensation is equal to the logarithm of the intensity of the stimulus, as long as it is referred to the threshold sensation”. The unit of sound sensation is the bel or bel, although the dB is always used, which is the abbreviation used for the decibel or decibel, the tenth part of the bel .

The perception of sound

As a general rule, the human ear hears sounds within a dynamic range of 20 Hz (0.02 kHz) to 20,000 Hz (20 kHz). The maximum limit usually decreases as you get older. In fact, many adults cannot hear more than 16 kHz. The lowest frequency that they have identified in a musical tone is 12 Hz under specific laboratory conditions. The tones that are between 4 and 16 Hz can be physically perceived by the body’s sense of touch. The range of intensity that audible sounds have is very wide. The eardrums of the human ear are sensitive to any kind of variation in sound pressure, being able to detect pressure changes as small as a few micropascals to more than a bar. Therefore, the sound pressure level can also be measured logarithmically, with pressures referenced to 20 µPa, The lower limit audibility is defined as 0 dB, although the upper limit is not defined, at least not as clear as thought. In this case, the upper limit is more a question of the limit of sound where the ear will be damaged or has great potential to cause permanent hearing damage. Delving deeper into the limits of audibility, it is determined that the minimum threshold at which a sound is not heard also depends on the frequency. When this minimum intensity is measured to test different frequencies, the absolute threshold depends on the absolute frequency of hearing, As a general rule, the ear has a peak sensitivity between 1 and 5 kHz, although threshold changes with age with more worn ears with the passage of time have a decrease in sensitivity that exceeds 2 kHz. The absolute hearing frequency is the lowest level of sound equalization. These indicate the sound pressure level (dB SPL) in the range of frequencies that are heard, which are perceived as being of equal loudness. The sound equalization was measured for the first time at Bell Laboratories in 1933, in the use of pure tones that are reproduced through headphones. The data that was collected is called Fletcher-Munson Curves thanks to the fact that they were the ones who made this measurement for the first time.