Presentation on SOUND by an audiologist Sa'adu Adamu, department of Audiology National Ear Care center Kaduna, Nigeria.

1. Introduction to sound and
Tuning fork test
By
Saadu Adamu
Should there be question after the class:
+2348028536352,
saadukauru@yahoo.com

2. Introduction
By definition “Audiology” is the branch of
science and medicine concerned with the
sense of hearing and balance. As an ENT
professional, audiology also involves
assessment, management and therapeutic
rehabilitation of people with hearing and
balance problems and associated disorders.
This include patients of all ages from newborn,
children, adult and elderly.

3. Defination
A pressure wave that propagate through an elastic
medium, which may be gas, liquid, or solid; waves
with a frequency between 20 and 20,000Hz provide
the stimulus for the subjective sensation of hearing.
The effect produced on the organ of hearing and its
central connection by the vibration of air or some
other medium
Subsonic sound; A Frequency of sound outside
human hearing range
 Infrasound: A frequency of sound below 20KHz for
human audibility, mostly use in research for
monitoring of Earthquakes and Volcanoes, Petroleum
formation below the earth and others
 Ultrasound: A frequency of sound above 20KHz uses
to make an image of the body especially in medicine.

4. Sound Generation
waves are generated by any vibrating body. For
example, when a violin string vibrates upon being
bowed or plucked, its movement in one direction
pushes the molecules of the air before it,
crowding them together in its path

5. Properties of Sound wave
• Compression or Crest
• Rarefaction or Trough
• Frequency/cycles per second
• Amplitude
• Wavelength
• phase

6. Sound Transmission
• Sound Transmission is the movement of sounds
from one place to another for a purpose.
• The speed to which sound move to another point
usually depends on medium of transmission and
its acoustics impedance
• For every doubling of distance, the sound level
reduces by 6 decibels (dB).

7. Behavior sound Transmission
Reflection; When sound travels in a given
medium, it strikes the surface of another
medium and bounces back.
 Reverberation is the persistence
of sound after the original sound stop, it is
measured in a unit of time(second). is the
time it takes the signal to diminish 60 dB
below the original sound.

8. Diffraction; The bending of waves
around small* obstacles and the
spreading out of waves beyond small*
openings

9. Refraction of sound is the change in direction
of a wave passing from one medium to
another or from a gradual change in the
medium (When sound enters the water from
air or from water to air,
a refraction phenomenon occurs).

10. Sound measurement
We measure sound intensity (also referred to
as sound power or sound pressure) in units called
decibels. Decibels (dB) are named in honor of
Alexander Graham Bell, the inventor of both the
telephone and the audiometer. Below are few unit
used in sound measurement;
 dB gain: decibel gain; the different between the
input SPL and the output SPL of an Amplifier or
hearing aid.
 dBHL: decibel hearing level used in Audiogram
 dBnHL: decibel normalised hearing level
 dB SPL: decibel sound pressure level.