When researching hearing I started with the ear. The ear
has 3 parts: the outer ear/pinna, the middle ear, and the inner ear. Basically,
the outer ear catches the sound waves, the middle ear turns the sound waves and
turns them into vibrations through the eardrum which transfers it to the inner
ear, which turns the vibrations into nerve signals that go to the brain.
http://kidshealth.org/kid/htbw/ears.html
As for sound
waves, they travel in a way that can be referred to as the inverse square law
where the magnitude of the sound is inversely related to the distance from the
source to the ear. How "loudly" you hear a sound is directly related
to how much the parts in your ear move.
Then there is
also Reverberation and Echoing. Reverberation is when sound bounces off of
something hard and flat. It’s when you shout hello and you hear hellooooooo.
Echo is when you shout hello and you hear hello hello hello hello hello…
In terms of
reverberation:
Good sound
projection of the rear of the enclosure requires a long enough reverberation
time.
Good clarity and
articulation requires a reverberation time that is not too long.
Good balance of
low and high frequencies, reverberation times for low frequencies are longer
than for high frequencies.
Even distribution
of sound, requires no large reflective surfaces or focusing of sound.
For an intimate
atmosphere, there should be a short delay between the direct and first
reflected sound.
I also found some guy giving tips to architects about
architectural acoustics
1)
Watch out
for SOUND REFLECTIONS. Straight surfaces reflect sounds back into the
central space making sound clarity muddy.
-angular surfaces bounce
sounds in different directions to keep sounds more pure.
2) Select ACOUSTICAL
TREATMENT carefully. Different materials absorb sound frequencies
differently. Make sure your acoustical treatments are absorbing the right sound
frequencies.
-material is important, and
you should choose them based on your intent
3) Diminish ECHOES when necessary. Be aware
that sounds traveling within 30 milliseconds of each other are perceived
without echo. Sounds traveling after the 30 millisecond threshold become echoes
of the original sound.
-not sure how to interpret
this one, except maybe the angles of the angular surfaces should not exceed a
certain number so it doesn’t cause echoes.
4) Don’t let other building systems get in the
way. NOISE CONTROL is important to keep in check as other building
systems (like HVAC systems) operate. Keep such clashing noises to a minimum.
-keep other systems out of the
way of acoustics, they are important to the experience.
5) Keep objects or other OBSTRUCTIONS out of
the way. Objects that obstruct a sound path can block high frequency sounds.
(Low frequency sounds can bend around objects.)
-don’t have unnecessary
decorations and such that could obstruct or change the path of the sound waves.
6) Get good PATTERN CONTROL. Make sure sound systems
for a room get good sound coverage. This will prevent feed-back and other sound
distortions.
-place your speakers
strategically so the sounds don’t interfere with each other, or do in the right
way
7) For out-of-the-way listening areas
get DISTRIBUTED SOUND SYSTEMS. Such “delay-fill” speakers operate with an
electronic delay so the sound matches and is synchronized.
-add additional speakers where
necessary
Most
of this is over my head, but it seems handy.
Grey= tips from Maria Lorena Lehman,
Red = My interpretation
http://sensingarchitecture.com/649/7-design-tips-for-best-architectural-acoustics/
When designing for acoustics, all of this must be taken into consideration, particularly, the geometry of the space, the materials, and the geometry of the materials. Different considerations must be taken into account for ceilings and walls as there is a different relationship between the user and each.
Images
http://www.payscale.com/career-news/2013/04/9-ways-that-sound-affects-our-health-wellbeing-and-productivity-infographic-
http://visual.ly/hearing-numbers
http://1technation.com/cold-helmets-stadium-design-impact-hearing-game-day/
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