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Impact of Multiple Speakers , Distance, and Placement

Enter your Speaker Sensitivity (SPL)   (dB 1W/1M)
 
1 watt/1meter SPL (sound pressure level) - Usually printed on the back of your speaker cabinet.
Highly sensitive speakers (sensitivity >95 SPL or even > 100), can produce extreme sound levels with minimal power. 
Speaker placement within room:
Amplifier power (watts) (watts)
Number of speakers:
(Note: Program assumes each speaker has the same sensitivity)
Listening position (number of feet from speakers) feet

Important Background Information

  • 1decibel (dB) is roughly the smallest change we can perceive.
  • Doubling the amplifier wattage results in ONLY a 3dB increase in volume ("slightly louder").  Switching from a 50 watt amplifier to a 100 watt amplifier or from a 100 watt amplifier to a 200 watt will only increase the volume by 3 dB as long as you use the same speakers.
  • In order to double the current volume requires roughly a 6 to 10 dB increase. A 6 dB increase requires 4 times the power! and a 10 dB increase requires a 10-fold increase in amplifier power.

Sound Levels

barely audible 0 dB - Threshold of hearing
10 dB - Rustling leaf
20 dB - very quiet  - Quiet room
30 dB - Soft whisper
40 dB Quiet library
50 dB Average home
60 dB - moderately loud. Ordinary conversation, Light traffic.
70 dB - Vacuum cleaner, Heavy traffic
80 dB - Very loud.  Garbage disposal.
90 dB - Diesel truck
100 dB -  Snowmobile, Motorcycle, Train, garbage truck, 15th row of rock concert, chainsaw,
          Level - 5 to 10 using earbuds and a standard IPOD or walkman.  Uncomfortably loud. 
110 dB - Jackhammer, power saw, symphony orchestra, front row of rock concert, Car horn.  Extremely loud
120 dB - Rock concert, Jet engine.  Painful.  Threshold of pain.

Perceptions of Increases in Decibel Level

Imperceptible Change -   1dB
Barely Perceptible Change -  3dB
Clearly Noticeable Change  - 5dB
About Twice as Loud - 10dB
About Four Times as Loud  - 20dB

dB SPL laws

Impact of the various changes on sound levels
Double amplifier wattage - increase of +3 dB
Double number of speakers - increase of +3 dB
Double distance from sound source -  Decrease of  - 6 dB
Halve distance from sound source - Increase of +6 dB
Double driver excursion - increase of +6 dB (note: Equivalent to doubling wattage and # of speakers)

-----Placement of Speakers--------------
Place speaker on the floor - increase of +3 dB -  half loading
Place speaker on floor, and against a wall - increase of +6 dB - quarter loading
Place speaker on floor, near a wall, and in the corner - increase of +9 dB eighth loading

Permanent Hearing Loss


Decibel Exposure Time Guidelines Accepted standards for recommended permissible exposure time for continuous time weighted average noise, according to NIOSH and CDC, 2002. Each 3 decibel (dB) increase above 85 decibels cuts the permissible exposure time in half.   Exceeding these times will likely result in permanent hearing loss.   
Continuous dB Permissible Exposure Time
85 db 8 hours
88 dB 4 hours
91 db 2 hours
94 db 1 hour
97 db 30 minutes
100 db 15 minutes
103 db 7.5 minutes
106 dB 3.75 min (< 4min)
109 dB 1.875 min (< 2min)
112 dB .9375 min (~1 min)
115 dB .46875 min (~30 sec)

Disclaimer

The authors make no claims of the accuracy of the information contained herein; and these suggested doses are not a substitute for clinical judgment. Neither GlobalRPh Inc. nor any other party involved in the preparation of this program shall be liable for any special, consequential, or exemplary damages resulting in whole or part from any user’s use of or reliance upon this material.PLEASE READ THE DISCLAIMER CAREFULLY BEFORE ACCESSING OR USING THIS SITE. BY ACCESSING OR USING THIS SITE, YOU AGREE TO BE BOUND BY THE TERMS AND CONDITIONS SET FORTH IN THE DISCLAIMER. Read the disclaimer