chapter 1 acoustic

1. CHAPTER 1 INTRODUCTION TO SOUND

2. DISCUSSION TOPICS
• Sound Noise & Acoustics
• Environmental Noise in Daily Life
• Human hearing
TOPIC LEARNING OUTCOME
• Differentiate between sound, noise & acoustics
• Recognized the sources of environmental noise in daily activities
• Understand how sound being heard by human and how noise
could affects human’s hearing

3. In life????
Before we start, grab your pop corn and watch this cartoon>>The Dr. Binocs Show

4. SOUND
Pressure
fluctuation or
disturbance
sensed by our
human ear at a
point in space.
NOISE
Often described
as “un-wanted”
sound
ACOUSTICS
The science of
sound, including
its production,
transmission, and
effects. It may
defined as the
generation,
transmission, and
reception of
energy in the form
of vibrational
waves in matter.

5. SOUND
Sound is energy transferred by the compression & rarefaction of matter: sound
waves are compressional waves collisions between molecules transfer energy from
molecule to molecule.
To understand further on sound, watch this >>>>https://youtu.be/nGKffdaI4Pg

6. SOUND
Sound is a travelling wave which consists of an oscillate pressure that
transmitted through the travelling medium and gave the sensation of
hearing.
Sounds are vibrations that travel through the air or some other medium
(solids and liquids) Watch this for further>>sound propagating medium
The loudness or intensity of a sound is measured in decibels (dB)
The frequency of a sound is measured in hertz (Hz).

7. •Everyday your world is filled with a multitude
of sounds.
•Sound can let you communicate with others
or let others communicate with you.
•The ability to hear is definitely an important
sense.
•Sound propagates in air with the speed of
approximately 340 m/s at sea level with
around 25˚C. (1224km/hour). Temperature of
air affects the sound speed.
•Air temperature increase, sound speed
increases
SOUND
Sound speed during summer and winter

8. NOISE

9. NOISE
WHY SOUND BECOME NOISE???
PEOPLE REACTION REPETITIVE NATURE
Birds singing
noisy birds sounds
Musics hardcore
music calm

10. NOISE
• Any undesired sound >>Noise
pollutant.
• It’s physical and emotional effects
are difficult to define quantitatively.
Different people may respond
differently to the same level of
noise. But above certain levels,
noise can affect everybody.
• It can lead to hearing loss, mental
stress and uncomfortable feelings
(irritations).
• It can also interfere with daily
activities such as reduce your focus
while working, studying, distract
you while watching television and
disturb your sleep.

11. NOISE
NOISE >80 dB

12. NOISE

13. ENVIRONMENTAL NOISE IN DAILY LIFE

14. Physiological
Psychological Anger, distress, changing human
behaviour, sleep disturbances,
communication disturbances
Loss of hearing, increases in
blood pressure, increased the
heart rate
(Al-Rahman et. al., 2012, Zulkifli et al., 2010)
NOISE EFFECTS

15. • Acoustics is a branch of physics that deals with the
study of mechanical waves in gases, liquids, and
solids including topics such as vibration, sound,
ultrasound and infrasound.
• Acoustics is science dealing with the production,
control, transmission, reception, and effects of sound.
• The term is derived from the Greek akoustos,
meaning “heard.”
ACOUSTICS

16. ACOUSTICS
ARCHITECTURAL ACOUSTICS ENVIRONMENTAL ACOUSTICS

17. • Acoustics or building acoustics is the science of
controlling noise in buildings.
• Study on minimization of noise transmission from one space to
another, the control of the characteristics
of sound within spaces themselves.
• Consideration in the design, operation and construction of
most buildings, to give significant impact on health and wellbeing,
communication and productivity.
• For example: when designing of spaces such as concert halls,
recording studios, lecture hall, classroom, quality of sound, its
intelligibility and clarity are the most important aspect that need
to be considered as early as in design stage to ensure the quality
of sound during the occupancy meets with requirement and
function of the space.
ACOUSTICS

18. ACOUSTICS
Architectural acoustics (also known as
building acoustics) is the science and
engineering of achieving a good sound within a
building and is a branch
of acoustical engineering.
The study relates between sound produced in a
space and its listener, and sound transmitted
from outside to inside of the building.

19. How sound is being heard by human??

20. HUMAN HEARING

21. HUMAN HEARING

22. HUMAN HEARING
• The threshold of hearing is the sound pressure level of the weakest sound the human ear can detect.
• Human’s ear response differently to sound at different frequency, threshold of hearing is different for sound at
different frequencies. However the limit for human’s threshold of hearing is between 10 dB to 0 dB.
• Nominal standard threshold of hearing at 1000 Hz is about 4 dB but 0 dB is used as the most convenient
reference.
Threshold of hearing

23. HUMAN HEARING
Threshold of pain is the minimum intensity at which an individual starts to feel pain.
Nominal figure for threshold of pain is 130 dB. However, most reference quote 120dB.
Younger persons are more tolerant at loud sounds than older persons because their protective mechanism are
more effective.
Threshold of pain

24. HUMAN HEARING sound journey to the brain

25. HUMAN HEARING
• The funnel-shaped pinna collects sounds.
• A pinna is positioned on each side of the head. Their
presence on both sides of the heads with the mass of the
head between makes possible the directional
identification of sound by difference of intensity and of
the time at which the sound arrives at each ear
• They are transmitted along the auditory canal and set
the ear drum into vibration.
• At the ear drum, sound energy, which is in fact air
pressure fluctuation is transformed into mechanical
energy of ear drum movement.
• The auditory canal of an adult ear is about 25 mm long
and has approximate cross sectional area of 40 mm2.
• It behaves as a quarter (1/4) wavelength resonator at
approximately 3000 Hz.
• This is the reason why human ear has its maximum
sensitivity around this frequency.
The Outer Ear

26. HUMAN HEARING
• There are three ear bones in the middle ear called the malleus
(also called the hammer), the incus (also called the anvil) and
the stapes (also called stirrup).
• The malleus is attached to the inner layer of the ear drum. As the
ear drum vibrates, so does the malleus. The vibration is
transmitted inward from the malleus to the incus and from incus
to the stapes. The stapes has a footplate and a superstructure. Its
footplate is seated in the oval window, which is the separation
between the middle ear and the inner ear. Vibration of the
stapes sets fluids inside the inner ear to vibrate.
• The eustachian tube connects the middle ear to the back of the
throat. It is normally closed but opens with swallowing or
coughing to equalize pressure between the middle ear and the
ambient pressure that is found in the throat
The Middle Ear

27. HUMAN HEARING
• The cochlea is located in the inner ear. It is filled with liquid and contains the hairy
sensory cells that convert sounds into nerve signal to be conducted through the
auditory portion of the eight cranial nerve to higher brain centers.
• Vibration of stapes footplate sets up a travelling wave pattern within the cochlea.
This wavelike pattern causes a shearing of the hairy sensory cells of the cochlea,
resulting in the generation of neural impulses which are then sent to the brain. The
brain interprets these neural impulses as sound.
• There are three semi-circular canal in the inner ear. They are lie in planes
orthogonal to one another. They have no auditory functions but help us maintain
our balance.
• The semi-circular canal have swellings. Within each swelling, there is a sense organ.
• In the sense organ, the hairs of hairy sensory cells are embedded in a gelatinous
fluid.
• When a person moves his head, the hair of the hairy sensory cells are bent by
gelatinous fluid, resulting in the sending of nerve signal to brain.
• Based on these nerve signals, the brain figures out how to maintain balance of the
body.
The Inner Ear

28. THE INNER EAR-COCHLEA
hearing process thru human ear

29. HUMAN HEARING