Humans perceive sound with frequencies in the range 20to 20,000 Hz. Speech lies in the middle of this range, 400 to 1000 Hz,while bells, sirens, and the knock of silverware on plates all extendabove the range for speech. Musical instruments that keep rhythm,such as drums and bass guitars, supply sounds with lower frequencies.Doorways act as natural filters, so noises sound different whenthey come from around corners. (a) Estimate the width of a typicaldoorway in your house. (b) Determine the sound frequency that correspondsto a wavelength comparable to the width of a doorway. (Suchwaves freely diffract around the corner of the door.) (c) Determine thefrequency of sound that would diffract only +-20 from directly forwardwhen passing through a doorway. (d) Based on your estimates,does a doorway act as a noticeable filter for sounds we can hear?(e) If so, which frequency range (low, middle, high) is harder to hearfrom around the corner of a doorway? (f) Experiment to see if you cannotice this effect. It is more readily perceived from outside a house asyou listen to sounds from inside. Why is this so?
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.
Humans perceive sound with frequencies in the range 20
to 20,000 Hz. Speech lies in the middle of this range, 400 to 1000 Hz,
while bells, sirens, and the knock of silverware on plates all extend
above the range for speech. Musical instruments that keep rhythm,
such as drums and bass guitars, supply sounds with lower frequencies.
Doorways act as natural filters, so noises sound different when
they come from around corners. (a) Estimate the width of a typical
doorway in your house. (b) Determine the sound frequency that corresponds
to a wavelength comparable to the width of a doorway. (Such
waves freely diffract around the corner of the door.) (c) Determine the
frequency of sound that would diffract only +-20 from directly forward
when passing through a doorway. (d) Based on your estimates,
does a doorway act as a noticeable filter for sounds we can hear?
(e) If so, which frequency range (low, middle, high) is harder to hear
from around the corner of a doorway? (f) Experiment to see if you can
notice this effect. It is more readily perceived from outside a house as
you listen to sounds from inside. Why is this so?
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