7 Del. Admin. Code § 1149-3.0
"Ambient Noise" means the all-encompassing background noise associated with a given environment without the sound contribution of the specific source in question.
"A-Weighted Sound Level" means the sound pressure level in decibels as measured with a sound level meter using the A-weighting network, which compensates for human hearing characteristics. The level so read is designated dB(A) or dBA.
"Best Practical Noise Control Measures" means noise control devices, technology, and procedures determined or approved by the Secretary to be the best practical, taking into consideration the age of the equipment and facilities involved, the process employed, capital expenditures, maintenance cost, technical feasibility and the engineering aspects of the applicable noise control techniques in relation to the control achieved and the non-noise control environmental impact.
"Commercial Area" means land used for purposes such as retail sales, personal services, civic centers, hotels, offices and office buildings, wholesale and warehouse storage.
"Construction" means any site preparation, assembly, erection, placement, demolition, substantial repair, alteration or similar action for public or private rights-of-way, structures, facilities or similar property.
"Day" means the hours between 7:00 a.m. and 10:00 p.m.
"Day-Night Average Sound Level (Ldn)" means the 24-hour energy average of the A-weighted sound pressure level, with the levels during the period 10:00 p.m. to 7 a.m. weighted by 10 dBA before averaging.
"Decibel (dB)" means a standard unit for measuring the sound pressure level. It is equal to 20 times the logarithm to the base 10 of the ratio of the pressure of the sound measured to a reference pressure, which is 20 micropascals.
"Emergency" means any occurrence or set of circumstances involving actual or imminent physical trauma or property damage which demands immediate actions.
"Equivalent A-Weighted Sound Level, abbreviated Leq(x)dB(A)" means the constant sound level that, in a given situation and time period (x), contains the same sound energy as the actual time-varying A-weighted sound.
"Farm Vehicle" means a wheeled device used for transportation in farming operations.
"Hertz (Hz)" means a unit of measurement of frequency formerly stated as, and numerically equivalent to, cycles per second.
"Impulse Sound" means sound of short duration, much less than one second, with an abrupt onset and rapid decay, separated in time by at least one second.
"Industrial Area" means land used for purposes such as publishing, research, development, testing, manufacturing, processing, fabricating or repairing, and may include residential land use, for caretaker, watchman or janitor.
"Infrasonic Sound" means sound pressure levels having frequencies below 16 Hz.
"Intrusion Alarm" means a device with an audible signal which, when activated, indicated intrusion by an unauthorized person.
"Intrusive Noise" means unwanted sound which intrudes over and above the existing noise at a given location. The relative intrusiveness of the sound depends upon its amplitude, duration, frequency, time of occurrence and tonal or informational content as well as the prevailing ambient noise level. A sound pressure level of 3 dB(A) above the ambient level is normally just discernable, with levels of 5 dB(A) to 10 dB(A) the lower level region for complaints.
"Motorboat" means any vessel which operates on water and is propelled by machinery.
"Night" means the hours between 10:00 p.m. and 7:00 a.m.
"Noise" means any sound which annoys or disturbs humans or which causes or tends to cause an adverse psychological or physiological effect on humans, excluding all aspects of noise regulated by the Federal Occupational Safety and Health Act.
"Noise Disturbance" means any sound which (a) endangers or injures the safety or health of humans or animals, or (b) annoys or disturbs a reasonable person of normal sensitivities, or (c) jeopardizes the value of property and erodes the integrity of the environment. Compliance with Sec. 71-1-6 herein shall constitute elimination of a noise disturbance.
"Octave" means the interval embracing eight diatonic degrees between two sounds having a basic frequency ratio of two. (One unit of the musical scale).
"Percentile Level" means the sound levels exceeded for the percentage of time in any measured period. Lio, Lso and Lgo, the levels exceeded for 100, 5096 and 9094 of the time, are frequently used as measures of peak, average and ambient levels respectively.
"Person" means any individual (s), corporation, company, association, society, firm, partnership or joint stock company, and includes the State and all of its political subdivisions, agencies and instrumentalities as well as any department, board or agency of the government of the United States.
"Pure Tone" means any sound which can be distinctly heard as a single pitch or a set of single pitches. For the purpose of this section, a pure tone shall exist if the one-third octave arithmetic average of the sound pressure levels of the two contiguous one-third octave bands by 15 dB for bands with center frequencies less than 160 Hz, by 8 dB for bands with center frequencies of 160 Hz to 400 Hz, and by 5 dB for bands with center frequencies greater than 400 Hz.
"Real Property Boundary" means an imaginary line along the ground surface, and its vertical extension, which separates the real property owned by one person from that owned by another person, but not including intra-building real property divisions.
"Residential Area" means land used for the primary purpose of providing human living accommodations.
"Secretary" means the Secretary of the Department of Natural Resources and Environmental Control.
"Sound" means an oscillation in pressure, particle displacement particle velocity or other physical parameters, in a medium with internal forces that causes compression and rarefaction of that medium. The description of sound may include any characteristic of such sound, including duration, intensity and frequency.
"Sound Amplifying Equipment" means any device for increasing the magnitude of the human voice, music or other sound.
"Sound Level" means the sound pressure level (SPL) obtained by the use of a sound level meter and frequency weighting network, such as A, B or C as specified in American National Standards Institute specifications for sound level meters (ANSI 51.4-1971, or the latest approved revision thereof). The unit of measurement is the decibel. If the frequency weighting employed is not indicated, the A-weighting shall apply.
"Sound Pressure" means the instantaneous difference between the actual pressure and the average or barometric pressure at a given point in space, as produced by sound energy.
"Stationary Noise Source" means a device which creates sound while fixed in position, including but not limited to residential, commercial or industrial machinery, pumps, fans, compressors, air conditioners and refrigeration equipment.
"Ultrasonic Sound" means sound pressure levels having frequencies above 20,000 Hz.
"Vibration" means an oscillatory motion of solid bodies of deterministic or random nature described by displacement, velocity, or acceleration with respect to a reference point, such that:
"Weekday" means any day Monday through Friday which is not a legal holiday.
7 Del. Admin. Code § 1149-3.0