Webster's dictionary defines the noun 'sound' as:

• A: the sensation perceived by the sense of hearing
• B: a particular auditory impression: TONE
• C: mechanical radiant energy that is transmitted by longitudinal pressure waves in a material medium (such as air) and is the objective cause of hearing ("Sound")

Definition A is interesting in contrast to C, as it suggests sound could be subjective or objective, bringing the whole "If a tree fell in a forest, and no one was there to hear it, would it make a sound?" argument. Definition B is of interest, as we will be discussing the different tones or sound colors inherent with different recording processes or media. But what is suggested with definition C is the crux here - sound is a wave motion, in which air pressure varies continuously above and below the prevailing atmospheric barometric pressure (Everest 6-7). 'Varies continuously' is of great importance because it suggests sound, if it must be put into these terms, is an analog phenomenon. That is, the pressure does not vary in discrete steps per a given time interval, as a digital circuit would - it varies in infinitely detailed steps over infinitely detailed passages of time. I will explain what I mean by this in the next three sections, but first we must understand the limitations of recording and the use of transducers and electricity to capture sound.

It is important for us to realize the limitations of recorded sound. We are talking about capturing sound by conversions to other mediums - we are not storing the variations in air pressure themselves, but rather representations of them which will never be perfect. Electricity does not respond like air, and magnetism does not respond like electricity. The truly 'sounds like I was there' recording is an impossibility. Every representational device will add characteristics that didn't exist in the original sound. When we factor in definition A of 'sound' above, we realize that no system of capture could mimic the peculiarities of every individual's hearing system. We can and should talk about sound in objective, scientific terms, but the end result is judged by the distinctly subjective hearing system of the individual.

Regardless of how the sound will later be recorded (analog or digital means), sound is always converted to an electrical signal before recording. A transducer is a device that converts energy from one form to another. Transducers commonly known to musicians include speakers, microphones, and electric guitar pickups. In the example of recording, the microphone converts acoustical energy to electrical energy, with voltage or current fluctuations in the resultant signal analogous to the air pressure variations of the actual sound (Davis and Jones 2). This signal may then be amplified, modified, or mixed with other sounds before being used to generate a magnetic field in the case of analog recording, or sampled (measured at discrete time intervals) in the case of digital recording.

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