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18.04.040 Definitions.

(Amended by Ordinance Nos. 159276, 164010, 175772, 184101 and 188959, effective May 24, 2018.)  The following words shall have the meanings ascribed to them in this Section:

A.  A‑scale (dBA): The sound level in decibels measured using the A‑weighting network as specified in ANSI S 1.4‑1971 for sound level meters.

B.  Ambient noise: The all-encompassing noise associated with a given environment, being usually a composite of sounds from many sources, near and far.

C.  City:  The City of Portland, Oregon, or the area within the territorial City limits of the City of Portland, Oregon, and such territory outside of this City over which the City has jurisdiction or control by virtue of ownership or any constitutional or Charter provisions, or any law.

D.  Construction:  Any and all activity necessary or incidental to the erection, demolition, assembling, altering, installing, repair or equipping of buildings, roadways, or utilities, including land clearing, grading, excavating and filling.

E.  Decibel (dB): A unit of measure of sound (See sound pressure level).

F.  Dwelling unit: A building or portion thereof intended for and regularly used for residential occupancy.

G.  Dynamic braking device: A device, used primarily on trucks and buses to convert the motor from an internal combustion engine to an air compressor for the purpose of vehicle braking without the use of wheel brakes.

H.  Emergency work: Work made necessary to restore property to a safe condition following a public calamity, work to restore public utilities, or work required to protect persons or property from imminent exposure to danger.

I.  Frequency:  The time of repetition of a periodic phenomenon, measured in Hertz (Hz) (formerly cps or cycles per second).

J.  High noise impact events: Events or activities which are attended by at least 250 people, and which may reasonably be assumed to cause increases of 15 dBA or more in the ambient noise level of a residential or commercial use area.

K.  Impulse sound:  A single pressure peak or a single burst (multiple pressure peaks) for a duration of not more than one second as measured on a peak unweighted sound pressure measuring instrument, as specified in ANSI S1.4-1971.

L.  Legal holidays: The days on which New Year’s Day, Memorial Day, Independence Day, Labor Day, Thanksgiving Day, and Christmas day are fixed by State law.

M.  Lot:  Any area, tract or parcel of land owned by or under the lawful control of one distinct ownership.  Abutting “platted lots” under the same ownership shall be considered a “lot.”  The lot line or boundary is an imaginary line at ground level which separates a lot and its vertical extension owned by one person from that owned by another.

N.  Motor vehicle: Any land vehicle which is, or is designed to be, self‑propelled or is designed or used for transporting persons or property.

O.  Motor vehicle racing: Any motor vehicular activity conducted at a recognized auto racing facility, involving motor vehicles participating in, but not limited to practice, qualifying and racing sessions, tests, training, and all other competitive and non-competitive displays, whether by individual vehicles, or by groups of vehicles.

P.  Narrow band sound: A sound whose frequencies occupy an octave band or less.

Q.  Noise disturbance: Any sound which: a) injures or endangers the safety or health of humans; or b) annoys or disturbs a reasonable person of normal sensitivities.

R.  Noise Sensitive Receiver:  A person receiving noise at any residential use or dwelling place, schools, churches, hospitals and libraries.

S.  Nonconforming use: A use of structure, building or land which was established as a permitted use and which has been lawfully continued pursuant to Title 33 of this Code, but which is not a permitted use in the zone in which it is now located.

T.  Octave band: An interval in Hertz between two frequencies having a ratio of 2:1.  For purposes of this Title, octave band sound pressure levels shall be measured at any of the following center frequencies: 31.5, 63, 125, 250, 500, 1,000, 2,000, 4,000 and 8,000 Hz.

U.  Offroad vehicle: Any motor vehicle operated off a public right‑of‑way.

V.  Person: Any individual, association, partnership, or corporation including any officer, department, bureau, agency or instrumentality of the United States, a state or any political subdivision of that state, including the City of Portland.

W.  Physical characteristics of sound: A descriptive term, encompassing the steady, impulsive or narrow band property of the sound, the level of the sound, and the extent to which it exceeds the background sound level.

X.  Plainly audible (sound): Any sound for which the information content of that sound is unambiguously communicated to the listener, such as, but not limited to, understandable spoken speech, comprehension of whether a voice is raised or normal, or comprehensible musical rhythms.

Y.  Public right‑of‑way: Any street, avenue, highway, boulevard, alley, easement or public space which is owned by or controlled by a public governmental entity.

Z.  Sound level: In dBA, the frequency weighted sound pressure level measured on the A‑scale of a sound level meter.

AA.  Sound level meter: A sound level measuring device, either Type I or Type II, as defined by ANSI specification S 1.4‑1971.  A sound level meter for the purpose of this Title shall contain at least an A‑scale and both fast and slow meter response.

BB.  Sound pressure level: In decibels (dB), is 20 times the logarithm to the base 10 of the ratio of the pressure of a given sound to the reference pressure.  The reference pressure is 20 micropascals per square meter.

CC.  Steady sound: A sound which remains essentially constant (±2 dB) during a two minute period of observation when measured with the fast response of the sound level meter.  Steady sound shall apply only to sound sources which operate or can reasonably be expected to operate for at least 15 minutes out of any one hour period.

DD.  Use: The purpose for which land or a building is arranged, designed, or occupied.

EE.  Watercraft: Any vehicle operated upon or immediately above the surface of the water.

FF.  Zone:  A classification of area of the City of Portland as described in Title 33 of the City Code, relating to the use to which property may be put.  For the purposes of this title, the zones are based upon the Land Use Zones, as defined in Title 33 as follows:


Open Space


Open Space

Residential Residential Farm/Forest
  Residential 20,000
  Residential 10,000
  Residential 7,000
  Residential 5,000
  Residential 2,500
  Residential 3,000
  Residential 2,000
  Residential 1,000
  High Density Residential
  Central Residential
  Commercial Residential
  Institutional Residential
  Campus Institutional 1
Commercial/ Mixed Use Commercial/Mixed Use 1
  Commercial/Mixed Use 2
  Commercial/Mixed Use 3
  Commercial Employment
  Central Commercial
  Campus Institutional 2
Industrial General Employment 1
  General Employment 2
  Central Employment
  General Industrial 1
  General Industrial 2
  Heavy Industrial