NOTE: Some general definitions have been made more specific
for the purposes of this chapter.
As used in this chapter, the following terms shall have the
meanings indicated:
All-encompassing sound at a given place, usually a composite
of sounds from many sources near and far.
American National Standards Institute.
Total of all sources of interference in a system used for
the production, detection, measurement, or recording of a signal,
independent of the presence of the signal.
Sound-pressure level for sound contained within a restricted
frequency band. Unit, decibel (dB).
Work and all related activities being done to erect, build,
demolish, or modify structures and/or to grade or contour terrain
for buildings, public and private roads, housing, and other structures.
The time duration of construction will be limited to that defined
by the permit.
Equipment used during construction including but not limited
to heavy trucks, pay loaders, tractors, power shovels, air compressors,
cranes, graders, jackhammers, hammers, nail guns, conveyors, concrete
and cement mixers, generators, welders.
The hours between 7:00 a.m. and 6:00 p.m.
Unit of A-weighted sound level. The weighted sound-pressure
level by the use of the A metering characteristic and weighting specified
in ANSI Specifications for Sound Level Meter.
Unit of level when the base of the logarithm is the 10th
root of 10, and the quantities concerned are proportional to power.
Unit symbol, db.
Equipment that are driven by either electric or air driven
motors or internal combustion engines, used for household applications.
Includes but not limited to lawn mowers, hedge trimmers, lawn and
garden tractors and related accessories, tillers, chain saws, drills,
saws, impact wrenches, portable generators, portable pumps, trimmers,
power washers, snow blowers, leaf and related blowers, mulchers, chippers,
vacuums, and related equipment.
The hours between 6:00 p.m. and 10:00 p.m.
The nominal exponential averaging time of 1/8 second as measured
with a sound level meter that complies with ANSI standards.
For a function periodic in time, the reciprocal of the period.
Unit, hertz (Hz).
Sinusoidal quantity that has a frequency which is an integral
multiple of the frequency of the periodic quantity to which it is
related.
Self-propelled, self-powered or pull-type equipment and machinery,
including engines, weighing 5,000 pounds or more, primarily employed
for construction, industrial, maritime, mining and forestry uses,
as such terms are commonly used and understood as a usage of trade.
The term "heavy equipment" shall not include: motor vehicles requiring
registration and certificates of title, or farm machinery, equipment
and implements sold or leased pursuant to dealer agreements with suppliers.
Heavy-duty vehicles, specially designed for executing construction
tasks, most frequently, ones involving earthwork operations. They
are also known as, "construction equipment," "construction plant,"
"earth movers," "engineering vehicles," or simply "equipment." They
usually comprise five equipment systems: implement, traction, structure,
power train, control and information.
Heating, ventilating, and air-conditioning equipment that
includes but is not limited to air handlers, condensing units, chillers,
air conditioners, fans and related air-moving devices, pressure regulating
and relief valves, and compressors.
A sudden burst of sound or noise with an extremely rapid
rise time of nanoseconds and sharp "Q" factor along with a rapid decay
time. Normally occurring as a single event or with sufficient time
separation between events to be perceived as discrete events by the
human ear.
The L90 is the "fast response" noise
level that is exceeded 90% of the time when measured over a specific
time period of 15 minutes.
A-weighted sound level in dBA per ANSI standards.
The equivalent continuous A-weighted sound level measured
over a finite time, e.g., 15 minutes, with an ANSI Type I integrating-averaging
sound level meter. The steady state, fluctuating and intermittent
components of a noise signal are averaged over a well-defined time
and the result is an equivalent average sound level that contains
the same energy as the total signal.
 |
|
Where:
| |||
|
Leq
|
=
|
equivalent continuous sound level (A-weighted), dBA
| |
|
PA(t)
|
=
|
A-weighted sound pressure,
| |
|
t1
|
=
|
starting time of averaging,
| |
|
t2
|
=
|
finishing time of averaging,
| |
|
T1-2
|
=
|
t2 - t1 = the
total integration time.
| |
The maximum A-weighted sound level that occurs on the crest
of a changing average noise level as measured with the "fast response"
of an ANSI Type I sound level meter for a specific time duration.
The amplitude of the real time waveform converted to decibels.
No averaging is used and the instantaneous high of the acoustical
signal is measured.
In acoustics, logarithm of the ratio of a quantity to a reference
quantity of the same kind. The base of the logarithm, the reference
quantity, and the kind of level shall be specified.
Spectrum whose components occur at a number of discrete frequencies.
Greatest fast (125-ms) A-weighted sound level, within a stated
time interval.
The hours between 10:00 p.m. and 6:00 a.m.
For airborne sound, unless specified to the contrary, it
is the A-weighted sound level.
The maximum value permitted by Table 264-10[1] for the A-weighted noise level that occurs on a receiving
property due to noise being generated at a source location. The value
of the noise level limit is a function of the time of day and the
zoning characteristic of the receiving property. Measurands include:
1) 15 minute Leq, 2) "fast response" LA, 3) "fast response" LMAX, and
4) "fast response" L90 as appropriate in this
chapter.
Ambient noise with background noise that is due to naturally
occurring sounds and noises that include but not limited to insects,
rustling leaves, wind effects on the environment, and lawfully occurring
transportation noise regulated by state and federal statutes. This
term will exclude other noises that may be covered by this chapter
that increase the ambient noise more than might reasonably be expected.
The interval between two sounds having a frequency ratio
of two. There are eight octaves on the keyboard of a standard piano.
A segment of the frequency spectrum separated by an octave.
The integrated sound-pressure level of only those sine-wave
components in a specified octave band.
Greatest absolute instantaneous sound pressure within a specified
time interval. Unit, pascal (Pa).
Line spectrum consisting of a signal at a single frequency.
Oscillation for which instantaneous magnitude is not specified
for any given instant of time. The instantaneous magnitudes of a random
noise are specified only by the probability distribution functions
giving the fraction of total time that the magnitude, or some sequence
of magnitudes, lies within a specified range.
The receiver location where excessive noise is occurring
due to noise being generated at a source location. The receiver location
will include the nearest point on the property line, any point on
the property line, or any point on the property at all heights above
ground level.
Off-road motor and engine driven vehicles not licensed by
the State of Pennsylvania. Includes but not limited to dirt motorcycles,
snowmobiles, and ATVs.
The weighted sound-pressure level obtained by the use of
a sound level meter and frequency weighting network, such as A, B,
or C as specified in ANSI specifications for sound level meters (ANSI
SI.4-1971, or the latest approved revision). If the frequency weighting
employed is not indicated, the A-weighting is implied.
Ten times the logarithm to the base 10 of the ratio of A-weighted
squared sound pressure to the squared reference sound pressure of
20 uPa, the squared sound pressure being obtained with fast (F) (125-ms)
exponentially weighted time averaging. Unit, decibel (dB) for ANSI,
decibel (dBA) for this chapter; symbol LA.
An instrument comprised of a microphone, amplifier, output
meter, and frequency weighting networks that is used for the measurement
of noise and sound levels.
Absolute instantaneous pressure in any given cycle of sound
wave at some specified time. Unit, pascal (Pa).
Root-mean-square instantaneous sound pressure at a point,
during a given time interval. Unit, pascal (Pa).
Ten times the logarithm to the base 10 of the ratio of the time-mean-square
pressure of a sound, in a stated frequency band, to the square of
the reference sound pressure in gases of 20 uPa. Unit, decibel (dB);
abbreviation, SPL; symbol, Lp.
For sound media other than gases, unless otherwise specified,
reference sound pressure is one micropascal (1 uPa).
A single-number rating of airborne sound insulation of a
building partition, derived by fitting a reference rating curve to
the sound transmission loss values measured for the 16 contiguous
1/3 octave frequency bands with nominal midband frequencies of 125
Hz to 4,000 Hz inclusive, by a standard method. The reference rating
curve is fitted to the 16 measured transmission loss values such that
the sum of deficiencies (transmission losses less than the reference
rating curve), does not exceed 32 dB, and no single deficiency is
greater than eight dB. Sound transmission class is the numerical value
of the ordinate (y axis) of the reference contour at 500 Hz. Unit,
decibel (dB); abbreviation, STC. For sound transmission class 50 dB,
for example, the reference rating curve consists of a straight line
from 34 dB at 125 Hz to 49 dB at 400 Hz; a straight line from 49 dB
at 400 Hz to 54 dB at 1,250 Hz; and a straight line constant at 54
dB from 1,250 Hz to 4,000 Hz.
The location of the source producing excess noise at a receiver
location. Includes both stationary and moving noise sources. Also
includes recreational vehicles and model airplanes used on public
and private property.
Description, for a function of time, of the resolution of a
signal into components, each of different frequency and (usually)
different amplitude and phase.
"Spectrum" is also used to signify a continuous range of components,
usually wide in extent, within which waves have some specified common
characteristic; e.g., "audio frequency spectrum."
A porous device used to cover the microphone of a sound level
meter to suppress the effect of air movement over the microphone that
causes false sound/noise. The total attenuation (insertion loss) of
the device will be limited to one dBA or less.
