Acoustics and Hearing Loss [ was Common house design
From: Sharon Villines (sharonsharonvillines.com)
Date: Sat, 23 May 2015 11:45:33 -0700 (PDT)
> On May 22, 2015, at 11:06 AM, Muriel Kranowski <murielk [at] vt.edu> wrote:

> So, a primary outcome should be "people can easily
> chat with the person next to them or across the (not too wide!!) table
> during meals.”

It is also becoming more well-recognized that any noise that you have to raise 
your voice to speak over is loud enough to damage hearing with as little as 30 
minutes of exposure. As in one CH dinner. Or amplified music.

Some ears are more susceptible to damage than others and some heal faster. 
Aging is partly physical decline and partly years of exposure to noise.

Normal conversation is variously measured at 55-60 decibels. Decibels are 
measurements of pressure and used in many fields. Sound places pressure on the 
ear drum and damages it depending on the amount of pressure for what length of 
time. It’s a bit like a tight wrist band. Putting it on is one thing but 
wearing it for an hour can cut off circulation. Several hours can cause 
permanent damage. The damage is incremental. Bill Clinton didn’t need a hearing 
aid at 50 for nothing.

I included a list of the damage levels below along with a link to the DC code 
on noise. I think it is a good one but it is never enforced. The officers like 
most people don’t believe that loud music is even loud. I can hear the high 
school football announcer on the loud speaker more than 4 blocks away. In the 
stands, all the kids hearing is in danger. Except maybe those in football 
helmets.

Many people consider the noise in our dining room to be exciting and a 
reflection of the fun people are having. Others stay home.

The DC code nicely summarized:

http://dcra.dc.gov/publication/noise-regulations-handbook-0

OSHA Standards (and OSHA is measuring for enforcement in workplaces, not 
usually the low levels recommended by hearing professionals.)

The number of hours of being exposed to a particular decibel level before it 
normally causes hearing damage. Some people are more susceptible than others.

8 hrs     90 (A subway train)
6 hrs    92 
4 hrs    95 
3 hrs    97 
2 hrs   100 
1.5 hrs   102 
1 hrs   105 
0.5 hrs    110 
0.25 hrs   115 (Rock drilling)

Ear plugs reduce sound levels 20-30 decibels. 

The following are measurements collected from various sources. The numbers vary 
but you can get the picture. A food court, I’ve measured at 70-80. At 80-90 is 
when you have to raise your voice to be heard. CH meals easily reach this level 
and above. We have a few people with very loud voices, plus the commercial 
washer and other people talking over it. Kids running around yelling. 

Remember the measurement scale above. Decibels are not measured like degrees. 
80 db is much louder than the equivalent of 20 degrees than 60 db and can cause 
damage in as little as 30 minutes by some measures.

188 Apollo Liftoff
163-170 Mauser Pistol
150 Snare Drums at 6 inches away
150 Trumpet Peaks at 5 inches away
150 Jet Take-Off
143-170 Rifles, a single exposure at this level can cause hearing loss
130 Jack Hammer
130 Threshold of Pain,
125 Chain Saw
120 Thunder Clap
120 Ambulance Siren
115 Rock Drilling
115 Pig squeals

113 56 seconds at this level can cause hearing loss.
110 Dance Club (91-96+) WHB 86 percent are above this.
105 WHO: 5 minutes a day can cause serious hearing loss.

103-107 Referee Whistle
103 Leaf Blower
95-120 Mower
93-103 Tractor
90  Subway
88 Food Blender
80-115 Motorcycle
80-115 Home Stereo
78 Heavy Traffic
70-80  Street Traffic
65 Conversation
55-65 Airport Terminal
50-60 Large Store
50-60 Office
50 Automobile at 50 miles an hour
15-20 Whisper
0-5 Threshold of hearing (0 = Healthy Kids)

Sharon
----
Sharon Villines
Takoma Village Cohousing, Washington DC
http://www.takomavillage.org




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