A cicada's mating call reaches 105 dB at a distance of 1.00 m from the insect. Calculate the decibel level at a distance of 25 m from 56 cicadas each producing the same sound intensity.
Properties of sound
A sound wave is a mechanical wave (or mechanical vibration) that transit through media such as gas (air), liquid (water), and solid (wood).
Quality Of Sound
A sound or a sound wave is defined as the energy produced due to the vibrations of particles in a medium. When any medium produces a disturbance or vibrations, it causes a movement in the air particles which produces sound waves. Molecules in the air vibrate about a certain average position and create compressions and rarefactions. This is called pitch which is defined as the frequency of sound. The frequency is defined as the number of oscillations in pressure per second.
Categories of Sound Wave
People perceive sound in different ways, like a medico student takes sound as vibration produced by objects reaching the human eardrum. A physicist perceives sound as vibration produced by an object, which produces disturbances in nearby air molecules that travel further. Both of them describe it as vibration generated by an object, the difference is one talks about how it is received and other deals with how it travels and propagates across various mediums.
Here, for the intensity calculation we use the formula,
I (dB) = 10 log[I/Io]
Corresponding sound intensity,
105 = 10 log[I/10-12]
I = 3.16 x 10-2 W/m2
At a distance of 25 m, the sound intensity is given by,
P = I x 4πd12 = 3.16 x 10-2 x (4π x 12) = 0.397 W
I (d=25 m) = P/4πd2 = 0.397/4π252 = 5.05 x 10-5 W/m2
Trending now
This is a popular solution!
Step by step
Solved in 2 steps
