From birth to death, we are in an ocean of sounds. In the city, we constantly hear the sounds of moving cars, conversations of passers-by, and background noises. Electrical appliances work at home, we include televisions, radios, computers. You can not notice these sounds, do not pay attention to them, but they affect our worldview and well-being. When we are, as it seems in silence, outside the city, in nature, sounds still exist around us. This is the noise of foliage, the buzzing of insects, the rustle of steps on the grass. Absolute silence on Earth in vivo does not exist.
What is sound?
From the point of view of physics, sound is elastic waves propagating in a medium and creating mechanical vibrations in it. What determines the pitch and our other sensations?
From a physiological point of view, sound is associated with hearing. And directly connected with our senses.
The medium for the propagation of sound waves can be air, water, metal and other substances.
Since sound is a wave process, it is described by the same parameters as any wave. This is the frequency, wavelength, amplitude, wave vector (direction), speed.
A person hears sounds in the range from 15 Hz to 20,000 Hz. The range below the level of hearing is called infrasound, above the level and up to 1 GHz is called ultrasound. Above 1 GHz is hypersound.
Pitch
Pitch is a subjective sensation of a person. We hear all the sounds on a scale from low to high. What determines the pitch? Mostly from the frequency of the sound wave. But the perception of height is also affected by its intensity. At high intensity, sounds seem lower.
The unit of pitch is chalk. Chalks are distributed on a scale at intervals that are perceived by ear as equal.
Scientists have found that if you play short pulses with an interval of 5 milliseconds, then by ear they will be perceived continuously.
Like any information in our senses, sound information is processed by the brain. Consider what the frequency of sound depends on. The so-called Shepard effect is known. A scale that creates the illusion of a constantly rising or falling tone, although nothing really changes. This is achieved by superimposing sound waves in octaves (multiple in frequency). This effect was intuitively used by Bach, Ravel, Chopin.
Tones of sound
A complex tone is the sound of several frequencies at once. A simple tone can be reproduced using a sound generator, or a tuning fork. A complex tone is created by musical instruments and a human voice. The complex tone spectrum consists of the fundamental frequency and many additional harmonics, the so-called overtones. What determines the pitch of the sound and the sound itself? It depends on the fundamental frequency of the tone. But the intensity affects the perception of pitch. The higher the intensity, the lower the sound.
Sound volume
Sound volume characterizes the level of sound sensation. What determines the volume and pitch? The perception of sound volume is a subjective sensation and depends both on the intensity of the sound and on age, gender, ethnicity, listening conditions. The feeling of loudness is described by the psychophysical law of Weber-Fechner. In accordance with this law, if the intensity of sound increases exponentially, then the feeling of loudness is arithmetic. (Logarithmic dependence). What determines the volume and pitch? From many reasons. The pitch seems lower when the volume increases. Man always low and high frequencies seem quieter than medium.
Sound timbre
The timbre is determined by the spectrum of the sound. The spectrum is colored with overtones (harmonics of the fundamental frequency). They give an emotional touch to any sound. What determines the pitch and timbre of a sound? They depend on the design and materials of musical instruments, on the characteristics of the human voice. The numerous overtones that appear give the sound a unique character.
Each of the famous Stradivarius violins had a unique timbre. This was determined by the shape of the resonator, and the type of wood, and even the varnish of the coating.
Some believe that the special perception of sound by man in ancient times contributed to its survival. To analyze external noise, it was necessary to understand what the pitch of the sound depends on, to isolate the sounds of a creeping predator from the mass of noise, sound frequencies, or to hear the approach of some natural disaster in time.
Now it is possible to synthesize any sounds, process existing audio recordings to achieve the desired effect. But even at the dawn of sound recording, sound combinations were made. An example of such an effect is the famous cry of Tarzan, created artificially in 1932.
Architectural acoustics
What determines the pitch? Of course, from the room in which it arises.
They knew about this in antiquity and built temples taking into account acoustic elements, the theoretical basis for which was developed subsequently. This is the acoustic shape of the domes, and acoustic shells.