properties of sound
TRANSCRIPT
SOUND AND ITS PROPERTIES At a Glance
Introduction
Sound waves can be studied by observing its properties.
These are the distinguishing characteristics of sound.
Properties of Sound
Pitch
Intensity
Loudness
Quality
Pitch
This refers to the highness or lowness of a sound.
It is dependent on the frequency of the sound.
Note Frequency (Hz)
C 262
C# or Db
277
D 294
D# or Eb
311
E 330
F 349
F# or Gb
370
G 392
G# or Ab
415
A 440
A# or Bb
466
B 494
C’ 524
Intensity
This refers to the energy transported by a wave per unit time across a unit area perpendicular to the energy flow. (Power/Area)
It is expressed in terms of W/m2.
Human ear can detect sounds with an intensity as low as 10-12 W/m2 and as high as 1 W/m2.
Loudness
This is a subjective interpretation that varies from person to person.
It is commonly measured in terms of decibels (dB).
It is related to the following The energy of a vibrating object The condition of the air the sound wave travels
through The distance between the observer and the sound
source
Loudness
This is a subjective interpretation that varies from person to person.
It is related to the following The energy of a vibrating object The condition of the air the sound wave travels through
The distance between the observer and the sound source
Relationship between intensity and loudness
is the sound level or loudness
I is the intensity of the sound source
Io is the intensity of sound at the threshold of hearing
Intensity of Various Sound Sources
Source of the Sound
Sound Level (dB)
Intensity (W/m2)
Jet plane at 30 m 140 100
Threshold of pain 120 1
Loud rock concert 120 1
Siren at 30 m 100 1 x 10-2
Auto interior at 90 kph
75 3 x 10-5
Busy street traffic 70 1 x 10-5
Talk at 50 cm 65 3 x 10-6
Quiet radio 40 1 x 10-6
Whisper 20 1 x 10-10
Rustle of leaves 10 1 x 10-11
Threshold of hearing
0 1 x 10-12
Sample Problems on Loudness and Intensity
At a busy street corner, the sound level is 70 dB. What is the intensity of sound there?
What is the intensity of the sound at the pain level of 120 dB?
What is the sound level of a sound whose intensity is 2.0 x 10-6 W/m2.
Quality
Also known as timbre or tone color
It is the distinguishing feature of a sound.