Today, many new settlers, arranging an apartment,forced to carry out additional work, including the soundproofing of their homes, tk. the standard materials used make it possible to only partly hide what is happening in their own home, and not be interested in the will of neighbors.
The speed of sound in solids affects howminimum density and elasticity of matter opposing the wave. Therefore, when equipping the premises, the layer adjacent to the supporting wall is made sound-proofing with “overlaps” from above and below. It allows to reduce the noise level in decibels sometimes more than 10 times. Then, basalt mats are laid, and plasterboard sheets on top, which reflect the sound outside the apartment. When a sound wave "flies" to such a construction, it fades in insulator layers that are porous and soft. If sound has more power, then the materials absorbing it may even heat up.
Упругие же вещества, такие, как вода, дерево, metals, well transmit sound vibrations, so we hear the beautiful "singing" of musical instruments. And some nationalities in the past determined the approach, for example, of riders, putting the ear to the ground, which is also quite elastic.
The speed of sound in km depends on the characteristics of theenvironment in which it is distributed. In particular, the process can be affected by its pressure, chemical composition, temperature, elasticity, density, and other parameters. For example, in a steel sheet, the sound wave travels at a speed of 5100 meters per second, in glass - about 5000 m / s, in wood and granite - about 4000 m / s. To convert speed to kilometers per hour, you need to multiply the figures by 3,600 (seconds per hour) and divide by 1,000 (meters per kilometer).
Скорость звука в км в водной среде различна для substances with different salinity. For fresh water at a temperature of 10 degrees Celsius, it is about 1450 m / s, and at a temperature of 20 degrees Celsius and the same pressure - already about 1490 m / s.
The salty environment is distinguished by a deliberately greater speed of sound vibrations.
Sound propagation in the air also depends ontemperature With the value of this parameter equal to 20 degrees Celsius, the sound waves travel at a speed of about 340 m / s, which is about 1200 km / h. And at zero degrees the speed slows down to 332 m / s. Returning to our apartment isolators, we can find out that in a material like cork, which is often used to reduce the level of external noise, the speed of sound in kilometers is only 1,800 km / h (500 meters per second). This is ten times lower than this characteristic in steel parts.
The sound wave is a longitudinalfluctuation of the environment in which it spreads. When passing, for example, the melody of a piece of music through an obstacle, its volume decreases, since fluctuation amplitude varies. At the same time, the frequency remains the same, thanks to which we hear the female voice as female, and the male voice as male. The most interesting is the place where the speed of sound in km is close to zero. This is a vacuum in which waves of this type barely propagate. To demonstrate how this works, physicists place a ringing alarm clock under the hood, from which they extract air. The more rarefied the air, the quieter the bell is heard.
