Reference

Definitions
The definitions of "pace," "rhythm," and "dynamics" inevitably involve such related aspects as drive, timing, involvement, flow, and coherence. "Pace," for example, connotes speed; indeed, the concepts "fast" or "slow" have often been applied to sound reproduction.

Pace: At the simplest level, pace is equivalent to tempo. While a listener may well have a good awareness of absolute tempo, there is a strong subjective element in the perception of the speed at which a musical work is performed. This is determined in part by what has come before. The same is true of the perceived velocity of a vehicle in which one is traveling. Exiting from a fast expressway, the transition to the lower speed seems surprisingly abrupt---one's judgment of speed has been dramatically affected by the preceding experience. The way a conductor and/or musicians vary the tempo strongly affects the perception of pace. This is done deliberately as an element of musical expression and interpretation, and is vital to good performances. It doesn't correlate strongly with measured elapsed time, a performance that sounds rushed sometimes taking longer than one which sounds better paced.

What many listeners fail to note is that weaknesses in the audio chain can give rise to errors which, in combination, suggest that the musical pace has become slower; the effect is one of impaired listener interest. (Other classifiable component errors also reduce the listener's interest in the reproduced music---impaired clarity, for example---but the scope of this essay is restricted to the perception of time.) When replay is rendered less interesting, pace suffers and time may indeed appear to go more slowly.

Timing: This relates specifically to the musical characterization of a performer's ability to synchronize his or her playing accurately with respect to a given beat or rhythmic pattern. The ear has an extraordinary ability to recognize playing which is not on or aligned to the beat. This includes deliberately time-shifted or syncopated playing, as unmusical errors here quickly destroy meaning.

It is a fascinating aspect of audio reproduction that hi-fi components, individually or in concert, can damage the subjective impression of good timing and of tight, coherent musicianship. For many familiar recordings in which good timing is known to be present, some audio components or systems conspire to give an aura of lassitude in which the musicians seem to be playing subtly out of time. This failing may, with practice and acuity, be discerned on just a few notes of a single voice or instrument. Here one may perceive a nuance of uncertainty, a hint of nervousness, or a feeling that the steady, controlled flow of a performance is not as even or as secure as it should be.

With good reproduction of good performances, there is a feeling of confidence and drive, coupled with an awareness of the power of fundamental rhythms and their changing nature as the composition unfolds. Accurate portrayal of rhythm, though certainly very important for classical music, is absolutely vital for rock music. With its short presentation and simpler, more accessible structure, rock's rhythmic element is the foundation of listener involvement. Without that foot-tapping association, that invitation to dance, rock quickly descends to the boring and the banal. Only the most creative and expressive music---for example, the work of Joni Mitchell---can survive such damage; and even this material benefits greatly from good replay timing.

Dynamics: Subjective dynamics play their part in the structure of musical pace and rhythm while carrying substantial weight in their own right. Fundamentally, dynamics are associated with the technical definition of "dynamic range," the range of allowable, cleanly handled signal between a system's noise floor and its overload point. Thus CD can have a very wide dynamic range; even with 16-bit systems, a dynamic range of 110dB is possible---ample for domestic use. However, this does not mean that CD in general has good subjective dynamics. Ironically, it does not.

Good dynamics are associated with an awareness of exciting lifelike contrasts between loud and soft sounds. Transients should be imbued with lifelike attack and sharpness, loud peaks really should sound explosively and dramatically loud. Those peaks should not be rounded, squashed, or compressed.