Hearing as an auditory sense.

1. HEARING

3. Acoustics
The science and
technology of sound,
including its production,
transmission, and
effects

4. • Transmit desired sounds
reliably and pleasantly to
the hearer
• Satisfactory to the human
regarding noise
• Minimizes sound-related
annoyance and stress
• Minimizes disruptions of
speech
• Prevents hearing loss
Acoustical design goal

5. Psycho-Acoustics
Describe how we
perceive sound in
relation to their physical
properties (pitch, timbre,
loudness, noise and
speech comprehension)

6. SOUND
Any vibration (passage of
zones of compression and
rarefaction through the air
or any other physical
medium) that stimulates an
auditory sensation.

7. Ear Anatomy
and Hearing

8. HOW DO WE HEAR?

9. The human HEARING range

10. can rarely hear
frequencies above
12 kHz
ADULT
can hear tones of
about 16 Hz to 20
kHz
YOUNG

11. RANGES OF ADULT HUMAN HEARING

12. SoundPressure
Level
𝑆𝑃𝐿 = log(𝑃2
𝑃₀−2
)
or
𝑆𝑃𝐿 = 20 log10( 𝑃𝑃₀−1)
Where:
Pₒ = the threshold of the
hearing
P = root-mean-square
(rms) sound pressure for
the existing sound

13. SOUND INTENSITYLEVELS

14. Airborne sound travels
through the ear canal
and excites the
eardrums and the
structures behind it
Pathwaysof Sound

15. Fox (1983) distinguished
between two different kinds
of music: background and
industrial.
Human Responses to Music

16. Sound that is unwanted,
objectionable, annoying, or
unacceptable to a person,
which is often but not always
loud
NOISE

17. Noise can create
negative emotions,
feelings of surprise,
frustration, anger, and
fear
HUMAN RESPONSE
TO NOISE

18. The damage is probably due to an overstimulation
of cell metabolism, leading to oxygen depletion
and destruction, or to exceeding the elastic
capacities of the physical structures.
Results of damage to the cochlear cilia, the organs
of Corti at the basilar membrane in the inner ear, or
the nerves leading to the CNS.
Temporary Threshold Shift (TTS)
and Permanent Threshold Shift
(PTS)
PhysiologicalEffects ofSound

19. PHYSIOLOGICAL EFFECTS OF NOISE

20. A permanent hearing
impairment resulting from
prolonged exposure to high
levels of noise
Noise-induced Hearing
Loss (NIHL))

21. As noise becomes more
intense, we become more
aroused and our
performance of certain
tasks can improve.
Beyond a certain level of
intensity, however, task
performance degrades.
EFFECTS OF NOISE

22. EFFECTS OF NOISE
ON HUMANPERFORMANCE

23. Three Strategies to
PREVENT NIHL

24. HEARING PROTECTION DEVICES
An earplug is a device
worn in the external ear
canal which is
commonly made from
vinyl, silicone,
elastomer formulations,
cotton and wax, spun
glass wool, and slow-
recovery closed-cell
foam