Bit Depth - Bit depth determines the loudness resolution or dynamic range of your digital audio; it gives you either jagged loudness steps or a smooth ramp between silence and very loud sound. (Note: Unless you are making professional audio products, audio files of 48 kHz with a 16-bit depth should be fine for your home projects. But do remember: You can always take away depth from a file, but you can’t add it once it’s gone or was never captured to begin with.)

	Common Bit Depth	Audio levels (steps)	Dynamic range
internet voice	8-bit	256	~48 dB
CD/Video	16-bit	65,536	~96 dB
prof audio	24-bi	16,700,000	~144 dB

Bit Rate = Sample Rate * bit depth * number of channels.
(see: Wikipedia - Audio Bit Depth)

Cross-fade - An audio cross-fade is where one audio clip’s sound dissolves into another’s. As one sound fades away, another sound increases volume and starts up - and they audibly step on each other in their crossing volumes.

Envelope - An envelope in audio refers to specific boundaries (parameters) that are set around the sound so that you are only hearing certain frequencies. In audio editing, key-frames are used to accomplish this.

Frequency - Frequency is measured in Hz (cycles per second) and determines the pitch of a sound you are specifically listening to (low frequency = low pitch; high frequency = high pitch). Different instruments have sounds that cluster in certain frequency ranges (i.e. bass guitar clusters low, Celtic slide whistle clusters high).

Hertz (Hz) - Hz is the SI unit for frequency; 1 Hz = 1 cycle per second. (SI refers to the International System of Units, taken from the French Système International d'unités.)

	Common Sample Rate	lowest frequency	highest frequency
human hearing	usually zero when asked to do chores	20	20,000
speech**	22,050 Hz	*	11,025
low-end audio	32,000 Hz	*	16,000
audio CD	44,100 Hz	*	22,050
prof audio	48,000 Hz	*	24,000

* Lowest frequency depends on the limits of the microphone and amplifier circuits used; can range anywhere from 0 Hz to 40 Hz.
** Speech energy (energy meaning "the core of "- in this case voice as a specific sound) is mostly present in the 400 Hz - 5 kHz range.

Level - level = volume

Sample Rate - The number of samples-per-second in digital audio. Your sample rate will determine the range of frequencies available (lowest pitch to highest pitch) within the audio clip with which you are working. Your sample rate divided by two will determine the maximum frequency or pitch supported. (see: Nyquist frequency and Nyquist-Shannon sampling theorem)

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