Sound

1
Sound

• Intensity

2
Intensity versus Loudness

• Loudness
• The perception of the rate at which sound enters
  your ear.
• Intensity
• The actual rate at which sound enters your ear.

3
Sound Intensity in Decibels

• 60 -- Normal conversation
• 50 -- Home refrigerator
• 40 -- Principals Office
• 30 -- Quiet library (NHRHS) whisper
• 20 -- Soft whisper
• 10 -- Rustle of leaves
• 0 -- Threshold of hearing

4
Sound Intensity in Decibels

• 110- Shouting in ear, Average rock
  concert, Dance club
• 100- Snowmobile, Subway train
• 90 -- Lawn mower, City traffic
• 85 -- No hearing protection needed for up
  to 8 hours.
• 80 -- Alarm clock, Hair dryer
• 70 -- Vacuum cleaner, Restaurant

5
Sound Intensity in Decibels

• 140 -- Firecrackers, Jet engine,
  Shotgun blast
• 130 -- Hard Rock concerts, Jack hammer
• 120 -- Car Stereos, Headphones
• 120 -- Threshold of PAIN

6
How Tough is the Human Body?

• Permanent hearing loss occurs at sound levels
  above 85 decibels.
• Symptoms/clues of possible hearing loss
• Ringing in ears
• This is a sign of permanent deafness
• Others tell your music is too loud (but its not
  loud to you).
• Every 5 decibel increase over 85 decibels
  DOUBLES the hearing loss/damage

7
What Does This Mean?

• 105 dB - 1/2 hour
• 100 dB - 1 hour
• Snowmobile, Subway train, Motorcycle
• 95 dB -- 2 hours
• 90 dB -- 4 hours
• Lawn Mower, Motorcycle
• 85 dB -- 8 hours

8
The SCARY Part

• 125 dB -- 1.6 minutes
• 120 dB -- 3.25 minutes
• Car stereos, Headphones
• Physical pain
• 115 dB -- 7.5 minutes
• 110 dB -- 15 minutes
• Average rock concert, Dance club

9
The SAD Part

• 140 dB -- .2 minutes (12 seconds)
• Firecrackers, Jet engine, Shotgun blast
• 135 dB -- .4 minutes (25 seconds)
• 130 dB -- .8 minutes (50 seconds)
• Hard rock concert, Jack hammer

10
Things to Ponder

• The average American teenager hears as well as
  an average 40 year old American adult.
• The average American teenager hears as well as
  most 70 year old Africans.
• Does this mean that your hearing is great ...or
  that it has deteriorated?