Explanation of Perceived Acoustic Characteristics
<strong>Clarity (articulation, intelligibility, definition)</strong>: The quality of sound that supports the comprehension of detail and the distinct separation of individual musical notes and articulations.
Clarity is achieved from strong direct sound to listeners, an abundance of quickly-arriving sound reflections (0.0 to 0.05 seconds after the direct sound). It depends on the size, shape and materials used in the architectural space, as well as the absence of noise. Rooms should be designed to project sound to the audience.
<strong>Loudness (volume, strength)</strong>: The overall quantity of sound, as heard by a listener.
Loudness is achieved through close proximity to a sound source and from an abundance of early and late-arriving sound reflections within a sound-reflective room. Loudness is achieved through the use of plaster, concrete, or other non-porous, massive sound-reflecting materials. Room shape also strongly influences the Loudness within a room.
<strong>Liveliness (running liveliness)</strong>: The sense of a persistence of sound as heard during ongoing speech or music.
Liveliness is achieved from a multitude of early and mid-arriving sound reflections (0.01 to 0.25 seconds after direct sound), typically arriving from sidewalls. Liveliness is achieved through a room shape that supports multiple lateral sound reflections. Rooms with near-parallel walls support Liveliness well.
<strong>Reverberance (decay, lingering)</strong>: The perceived lingering of sound following the cessation of music.
Reverberance results from an abundance of late-arriving sound reflections (0.25 to 2.20 seconds after direct sound) that have traveled long distances within the room due to multiple sound reflections. Room size, geometry and material selections all affect Reverberance. The perception of Reverberance is influenced strongly by the Running Liveliness in the room.
<strong>Echoes</strong>: Distinct and audible repetition of a sound. Echoes are generally undesirable and are detrimental to clarity.
Echoes are due to individual, long-delayed sound reflections. Note, “echoes” and “reverberation” differ. Large, flat and / or concave sound reflecting surfaces 30 feet or more from a listener can produce Echoes.
<strong>Dynamic Range</strong>: The ability to experience both pianissimo passages with Clarity and fortissimo tutti passages without harshness.
Dynamic Range is achieved by optimizing the acoustic characteristics of Loudness, Clarity and Silence.
<strong>Envelopment (immersion)</strong>: The sense of being surrounded by sound.
Envelopment results from 3-dimensional sound fields containing early, mid-and late-arriving reflections arriving from the sides, the rear and the front of a listener. Envelopment is influenced by room size and shape.
<strong>Spaciousness</strong>: Refers to the perceived width of a sound source, such as an orchestra. The orchestra will sound larger than it actually is.
Spaciousness occurs in the presence of early-arriving sound reflections from sidewalls located next to or in front of performers. Spaciousness of sound is achieved by proper room size and shape and / or the presence of sound diffusing surfaces, particularly at the forward portion of the hall.
<strong>Warmth (bass response)</strong>: The tonal quality resulting from an abundance of low-pitched sound (bass sound) within a room.
Warmth is achieved when the early, mid and / or late arriving sound contains more low-pitched sound than mid and high-pitched sound. Warmth of sound is determined by the overall weight of wall and ceiling surfaces and the overall size of sound reflecting surfaces. Massive and stiff walls are needed to achieve Warmth.
<strong>Silence</strong>: The total absence of continuous or intermittent extraneous noise.
Silence is achieved through carefully engineered air conditioning and electrical systems designed for silent operation. Intruding noise is controlled by properly designing door, wall, roof, and other building systems. The absence of noise is extremely important for the enjoyment of music.