You and a friend are talking on the lawn outside of a musical performance hall. You hear a sustained pure frequency of a sound wave due to someone inside the hall testing the acoustics. The sound exits a single open doorway of width 1.23 m and makes its way to you. Your friend pulls out his smartphone and uses an app to instantly determine the frequency of the sound. He challenges you to guess the frequency. Not having the same app, you can't do the same thing on your smartphone, but you can apply your physics understanding. You walk over until you are standing straight out and far away from the open door on a line perpendicular to the wall of the building. You take a reading on your smartphone compass. Then you start walking in a circular arc centered on the open doorway. At each point on the arc, you can aim your smartphone at the door, perform a compass reading, and convert that to an angular position along the arc measured from the line straight out from the doorway, which you call 0°. You find that there are minima in the sound intensity at angles of 17.1°, 35.9°, and 61.6° from the line straight out from the doorway. You perform a calculation on the calculator app on your smartphone and proudly tell your friend what the frequency of the sound is (in Hz). What would be the frequency? (Assume the speed of sound in air is 343 m/s. Consider that wave behaviour applies to sound waves as well)
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.
You and a friend are talking on the lawn outside of a musical performance hall. You hear a sustained pure frequency of a sound wave due to someone inside the hall testing the acoustics. The sound exits a single open doorway of width 1.23 m and makes its way to you. Your friend pulls out his smartphone and uses an app to instantly determine the frequency of the sound. He challenges you to guess the frequency. Not having the same app, you can't do the same thing on your smartphone, but you can apply your physics understanding. You walk over until you are standing straight out and far away from the open door on a line perpendicular to the wall of the building. You take a reading on your smartphone compass. Then you start walking in a circular arc centered on the open doorway. At each point on the arc, you can aim your smartphone at the door, perform a compass reading, and convert that to an angular position along the arc measured from the line straight out from the doorway, which you call 0°. You find that there are minima in the sound intensity at angles of 17.1°, 35.9°, and 61.6° from the line straight out from the doorway. You perform a calculation on the calculator app on your smartphone and proudly tell your friend what the frequency of the sound is (in Hz). What would be the frequency?
(Assume the speed of sound in air is 343 m/s. Consider that wave behaviour applies to sound waves as well).
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