Conn. Agencies Regs. § 22a-69-1.2 - Acoustic terminology and definitions

(a) All acoustical terminology used in these Regulations shall be in conformance with the American National Standards Institute (ANSI), "Acoustical Terminology," contained in publication S1.1 as now exists and as may be hereafter modified. The definitions below shall apply if the particular term is not defined in the aforesaid ANSI publication.

(b) audible range of frequency means the frequency range 20 Hz to 20,000 Hz which is generally considered to be the normal range of human hearing.

(c) background noise means noise which exists at a point as a result of the combination of many distant sources, individually indistinguishable. In statistical terms, it is the level which is exceeded 90% of the time (L₉₀) in which the measurement is taken.

(d) continuous noise means ongoing noise, the intensity of which remains at a measurable level (which may vary) without interruption over an indefinite period or a specified period of time.

(e) decibel (dB) means a unit of measurement of the sound level.

(f) excessive noise means emitter Noise Zone levels from stationary noise sources exceeding the Standards set forth in Section 3 of these Regulations beyond the boundary of adjacent Noise Zones.

(g) existing noise source means any noise source(s) within a given Noise Zone, the construction of which commenced prior to the effective date of these Regulations.

(h) fluctuating noise means a continuous noise whose level varies with time by more than 5 dB.

(i) frequency means the number of vibrations or alterations of sound pressure per second and is expressed in Hertz.

(j) hertz (Hz) means a unit of measurement of frequency formerly stated as, and numerically equal to, cycles per second.

(k) impulse noise means noise of short duration (generally less than one second), especially of high intensity, abrupt onset and rapid decay, and often rapidly changing spectral composition.

(l) infrasonic sound means sound pressure variations having frequencies below the audible range for humans, generally below 20 Hz; subaudible.

(m) L₁₀ means the A-weighted sound level exceeded 10% of the time period during which measurement was made.

(n) L₅₀ means the A-weighted sound level exceeded 50% of the time period during which measurement was made.

(o) L₉₀ means the A-weighted sound level exceeded 90% of the time period during which measurement was made.

(p) octave band sound pressure level means the sound pressure level for the sound contained within the specified preferred octave band, stated in dB, as described in ANSI S1.6-1967: Preferred Frequencies and Band Numbers for Acoustical Measurements.

(q) peak sound pressure level means the absolute maximum value of the instantaneous sound pressure level occurring in a specified period of time.

(r) prominent discrete tone means the presence of acoustic energy concentrated in a narrow frequency range, including, but not limited to, an audible tone, which produces a one-third octave sound pressure level greater than that of either adjacent one-third octave and which exceeds the arithmetic average of the two adjacent one-third octave band levels by an amount greater than shown below opposite the center of frequency for the one-third octave band containing the concentration of acoustical energy.

[THETA] Octave Band Center Frequency (Hz)	dB
100	16
125	14
160	12
200	11
250	9
315	8
400	7
500	6
630	6
800	5
1000	4
1250	4
1600	4
2000	3
2500	3
3150	3
4000	3
5000	4
6300	4
8000	5
10000	6

(s) reference pressure is 0.00002 Newtons per square meter (N/M²), or 20 microPascals, for the purposes of these Regulations.

(t) sound means a transmission of energy through solid, liquid, or gaseous media in the form of vibrations which constitute alterations in pressure or position of the particles in the medium and which, in air, evoke physiological sensations, including, but not limited to, an auditory response when impinging on the ear.

(u) sound analyzer means a device, generally used in conjunction with a sound level meter, for measuring the sound pressure level of a noise as a function of frequency in octave bands, one-third octave bands or other standard ranges. The sound analyzer shall conform to Type E, Class II, as specified in ANSI S1.11-1971 or latest revision.

(v) sound level means a frequency weighted sound pressure level, obtained by the use of metering characteristics and the weighting A, B, or C as specified in ANSI, "Specifications for Sound Level Meters," S1.4-1971 or latest revision. The unit of measurement is the decibel. The weighting employed must always be stated as dBA, dBB, or dBC.

(w) sound level meter means an instrument, including a microphone, an amplifier, an output meter, and frequency weighting networks for the measurement of sound levels. The sound level meter shall conform to ANSI Specifications for Sound Level Meters S1.4-1971.

(x) sound pressure level (SPL) means twenty times the logarithm to the base ten of the ratio of the sound pressure in question to the standard reference pressure of 0.00002 N/M². It is expressed in decible units.

(y) ultrasonic sound means sound pressure variations having frequencies above the audible sound spectrum for humans, generally higher than 20,000 Hz; super-audible.

(z) vibration means an ascillatory motion of solid bodies of deterministic or random nature described by displacement, velocity, or acceleration with respect to a given reference point.

Notes

Conn. Agencies Regs. § 22a-69-1.2

Effective June 15, 1978