Connecticut Administrative Code › Title 22a - Environmental Protection › 69 - Control of Noise › Section 22a-69-1.2 - Acoustic terminology and definitions

Current through July 10, 2024
(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)
L
10
means the
			 A-weighted sound level exceeded 10% of the time period during which measurement
			 was made.
(n)
L
50
means the
			 A-weighted sound level exceeded 50% of the time period during which measurement
			 was made.
(o)
L
90
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.