6
USING ADOBE AUDITION
Digital audio fundamentals
Last updated 2/16/2012
Understanding bit depth
Bit depth determines dynamic range. When a sound wave is sampled, each sample is assigned the amplitude value
closest to the original wave’s amplitude. Higher bit depth provides more possible amplitude values, producing greater
dynamic range, a lower noise floor, and higher fidelity.
For the best audio quality, Audition transforms all audio in 32-bit mode and then converts to a specified bit depth
when saving files.
Higher bit depths provide greater dynamic range.
Measuring amplitude in dBFS
In digital audio, amplitude is measured in decibels below full scale, or dBFS. The maximum possible amplitude is 0
dBFS; all amplitudes below that are expressed as negative numbers.
Note: A given dBFS value does not directly correspond to the original sound pressure level measured in acoustic dB.
Audio file contents and size
An audio file on your hard drive, such as a WAV file, consists of a small header indicating sample rate and bit depth,
and then a long series of numbers, one for each sample. These files can be very large. For example, at 44,100 samples
per second and 16 bits per sample, a mono file requires 86 KB per second—about 5 MB per minute. That figure doubles
to 10 MB per minute for a stereo file, which has two channels.
Sample rate Quality level Frequency range
11,025 Hz Poor AM radio (low-end multimedia) 0–5,512 Hz
22,050 Hz Near FM radio (high-end multimedia) 0–11,025 Hz
32,000 Hz Better than FM radio (standard broadcast rate) 0–16,000 Hz
44,100 Hz CD 0–22,050 Hz
48,000 Hz Standard DVD 0–24,000 Hz
96,000 Hz Blu-ray DVD 0–48,000 Hz
Bit depth Quality level Amplitude values Dynamic range
8-bit Telephony 256 48 dB
16-bit Audio CD 65,536 96 dB
24-bit Audio DVD 16,777,216 144 dB
32-bit Best 4,294,967,296 192 dB
192 dB
144 dB
48 dB
0 dB
96 dB
8-bit
16-bit 24-bit 32-bit
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