What are the properties of sound?

Answer 1

Three fundamental characteristics of sound: speed, frequency, and intensity (loudness).

Speed: The speed of sound in air actually depends on the temperature of the air. As a standard, we will say that the speed of sound is 340m/s at 15 °C. If you are not told anything different in a question, use this value.

Frequency: If you are doing calculations of the wavelength or frequency of sound, you still use the standard formula

f = v/λ

where f is frequency, v is "phase velocity", i.e the speed of sound, and λ is the wavelength.

Loudness: The loudness of a sound depends on the wave's amplitude. The system used to measure the loudness of sounds is the decibel system, given the unit dB.

Sound is a mechanical wave produced by vibrating bodies. For example, when an object such as a tuning fork or the human vocal cords is set into vibrational motion, the surrounding air molecules are disturbed and are forced to follow the motion of the vibrating body. The vibrating molecules in turn transfer their motion to adjacent molecules causing the vibrational disturbance to propagate away from the source. When the air vibrations reach the ear, they cause the eardrum to vibrate; this produces nerve impulses that are interpreted by the brain. . All matter transmits sound to some extent, but a material medium is needed between the source and the receiver to propagate sound. This is demonstrated by the well-known experiment of the bell in the jar. When the bell is set in motion, its sound is clearly audible. As the air is evacuated from the jar, the sound of the bell diminishes and finally the bell becomes inaudible. . The propagating disturbance in the sound-conducting medium is in the form of alternate compressions and rarefactions of the medium, which are initially caused by the vibrating sound source. These compressions and rarefactions are simply deviations in the density of the medium from the average value. In a gas, the variations in density are equivalent to pressure changes. . Two important characteristics of sound are intensity, which is determined by the magnitude of compression and rarefaction in the propagating medium, and frequency, which is determined by how often the compressions and rarefactions take place. Frequency is measured in cycles per second, which is designated by the unit hertz after the scientist Heinrich Hertz. The symbol for this unit is Hz. (1 Hz = 1 cycle per second.)