ALIGNMENT: The adjustment of tape-head azimuth and of tape-recorder circuitry to achieve optimum performance from the particular type of tape being used.

AMBIENCE: Room acoustics, early reflections and reverberation. Also, the audible sense of a room or environment surrounding a recorded instrument.

AMPLITUDE/PEAK: On a graph of a sound wave, the sound pressure of the waveform peak. On a graph of an electrical signal, the voltage of the waveform peak. The amplitude of a sound wave or signal as measured on a meter is 0.707 times the peak amplitude.

BALANCE: The relative volume levels of various tracks or instruments.

BASIC TRACKS: Recorded tracks of rhythm instruments (bass, guitar, drums, and sometimes keyboard).

BOUNCING TRACKS: A process in which two or more tracks are mixed, and the mixed tracks are recorded on an unused track or tracks. Then the original tracks can be erased, which frees them up for recording more instruments.

CD-R: CD-Recordable, a recordable compact disc that cannot be rewritten. Once recorded, it cannot be erased and reused.

CD-RW: CD-Rewritable, a recordable compact disc that can be rewritten. Once recorded it can be erased and reused.

CLEAN: Free of noise, distortion, overhang, leakage. Not muddy.

CLEAR: Easy to hear, easy to differentiate. Reproduced with sufficient high frequencies.

COMPRESSION: 1. The portion of a sound wave in which molecules are pushed together, forming a region with higher-than-normal atmospheric pressure. 2. In signal processing, the reduction in dynamic range or gain caused by a compressor. 3. In computing, data compression reduces the number of bytes in a file without losing essential information.

CONTROL ROOM: The room in which the engineer controls and monitors the recording. It houses most of the recording hardware.

DECIBEL: The unit of measurement of audio level. Ten times the logarithm of the ratio of two power levels. Twenty times the logarithm of the ratio of two voltages.

DIGITAL RECORDING: A recording system in which the audio signal is stored in the form of binary digits.

EDITING: The cutting and rejoining of magnetic tape to delete unwanted material, to insert leader tape, or to rearrange recorded material into the desired sequence. Also, the same actions performed with a digital audio workstation, hard-disk recorder, or MiniDisc recorder-mixer--without cutting any tape.

EQUALIZER: A circuit (usually in each input module of a mixing console, or in a separate unit) that alters the frequency spectrum of a signal passed through it.

FREQUENCY: The number of cycles per second of a sound wave or an audio signal, measured in hertz (Hz). A low frequency (for example, 100 Hz) has a low pitch; a high frequency (for example, 10,000 Hz) has a high pitch.

HISS: A noise signal containing all frequencies, but with greater energy at higher octaves. Hiss sounds like wind blowing through trees. It is usually caused by random signals generated by microphones, electronics, and magnetic tape.

HUM: An unwanted low-pitched tone (60 Hz and its harmonics) heard in the monitors. The sound of interference generated in audio circuits and cables by AC power wiring. Hum pickup is caused by such things as faulty grounding, poor shielding, and ground loops.

LIVE: 1. Having audible reverberation. 2. Occurring in real-time, in person.

LIVE RECORDING: A recording made at a concert. Also, a recording made of a musical ensemble playing all at once, rather than overdubbing.

LOOP: In a sampling program, to play the sustain portion of a sound's envelope repeatedly.

MASTERING: The final step in the production of an album where they add the final “polish” to the recording. This is done by technically enhancing the clarity of the mixes. This makes the compilation of songs sound more coherent, more “together”. This also ensures that the mixes sound well on all listening devices.

MIX: 1. To combine two or more different signals into a common signal. 2. A control on a delay unit that varies the ratio between the dry signal and the delayed signal.

MIXDOWN: The process of playing recorded tape tracks through a mixing console and mixing them to two stereo channels for recording on a two-track tape recorder.

MULTITRACK: Referring to a recorder or tape-recorder head that has more than two tracks.

NOISE-REDUCTION SYSTEM: A signal processor (Dolby or dbx) used to reduce tape hiss (and sometimes print-through) caused by the recording process. Some of these systems compress the signal during recording and expand it in a complementary fashion during playback.

REMIX: To mix again; to do another mixdown with different console settings or different editing.

SAMPLING: Recording a short sound event into computer memory. The audio signal is converted into digital data representing the signal waveform, and the data is stored in memory chips, tape or disc for later playback.

SESSION: 1. A time period set aside for recording musical instruments, voices, or sound effects. 2. On a CD-R, a lead-in, program area, and lead-out.

STUDIO: A room used or designed for sound recording.