Game Development Reference
In-Depth Information
Source
Power (watts/m sq)
SPLdB
Threshold of pain
Jet take off from 500 feet
Medium-loud rock concert
Circular saw
New York subway
Jack hammer from 50 feet
Vacuum cleaner from 10 feet away
Normal conversation
Light traffic from 100 feet away
Soft conversation
Whisper from 5 feet away
Average household silence
Breathing
Threshold of hearing
10
1
.1
.01
.001
.0001
.00001
.000001
.0000001
.00000001
.000000001
.0000000001
.00000000001
.000000000001
130 dB
120 dB
100 dB
90 dB
80 dB
70 dB
60 dB
50 dB
40 dB
35 dB
30 dB
20 dB
10 dB
0 dB
Increasing intensity of a variety of common sounds in decibels, from near total silence to extremely
loud. Also note the increase in power at each of these levels.
resolution in a sample is equal to about 6dB (decibels) of dynamic range.
We can't explain what decibels are, except to say you should really know
how decibels work if you don't already.
Adding more bits gives us a larger
dif erence between our quietest volume
and our loudest volume. A rule of thumb
is that around 90-100dB is commonly
associated with digital media. CD is
recorded at 16-bit, so multiplying 6 × 16
gets us 96dB, roughly the dif erence
between a pin drop and a jet plane
going by your ear. DVD audio is recorded
at 24-bit, which is 144dB.
There are many dif erent compression
types used in games depending on the
hardware platform, but probably the
most popular one out there is the MP3
codec. Apple has gravitated towards the
AAC codec, while many games use the
more recently developed Ogg Vorbis
(OGG) codec, due to its open source
nature.
Diagram showing basic analog to digital audio conversion. The larger the sample rate
and bit depth, the larger the resulting i le.
