Noise Impact Assessment Calculator

Calculate received noise levels at a receptor from a point source accounting for distance, atmospheric absorption, ground effects, and barriers per ISO 9613-2.

Inputs

Source level (dBA)

Receiver distance (ft)

Reference distance (ft)

Ground type

Barrier height (ft)

Receiver land use

Tab to move between fields

Results

Received level (dBA)

62.8

Total attenuation (dB)22.2

Geometric spreading (dB)20

Barrier insertion loss (dB)0

Regulatory threshold (dBA)60

Threshold exceedance (dBA)2.8

Required barrier height (ft)0

Distance to threshold (ft)889

How to Use This Calculator

Enter Source Level (dBA) from equipment specifications or field measurements.
Set Receiver Distance (ft) and Reference Distance (ft) for the inverse square law baseline.
Select Ground Type (hard/reflective or soft/absorptive) and Barrier Height (ft) if present.
Choose Receiver Land Use (residential, commercial, industrial) to apply the applicable noise standard.
Review Received Level (dBA) and compare to local ordinance limits or FHWA noise thresholds.

How the result changes with Source level (dBA)

Source level (dBA)	Received level (dBA)
51	28.8
79	56.8
112	89.8
139	116.8

What each input means

Source level (dBA): A-weighted sound power or pressure level of the noise source at the reference distance.
Receiver distance (ft): Distance from noise source to receiver location.
Reference distance (ft): Distance at which the source level was measured.
Ground type: 0 = Hard (pavement/water), 1 = Mixed, 2 = Soft (grass/soil/vegetation).
Barrier height (ft): Effective height of noise barrier above line of sight (0 = no barrier).
Receiver land use: 0 = Residential (night), 1 = Residential (day), 2 = Commercial, 3 = Industrial.

What each result means

Received level (dBA): Predicted A-weighted sound level at the receiver.
Total attenuation (dB): Combined loss from distance, atmosphere, ground, and barriers.
Geometric spreading (dB): Attenuation due to distance (inverse square law).
Barrier insertion loss (dB): Noise reduction from barrier (Maekawa approximation).
Regulatory threshold (dBA): Applicable noise limit for the receiver land use.
Threshold exceedance (dBA): Amount above/below the regulatory threshold (negative = compliant).
Required barrier height (ft): Barrier height needed at midpoint to meet threshold (if no barrier present).
Distance to threshold (ft): Distance at which source attenuates to meet threshold (no barrier).

How this is calculated

Worked example, using the default values

Identify Input Parameters
4 parameters
Source level (dBA) = 85, Receiver distance (ft) = 500, Reference distance (ft) = 50, Ground type = 1 = 6 input(s) provided
Calculate Received level
Received level = sourceLevelDba - totalAttenuation
62.8 = 62.8
Calculate Total attenuation
Total attenuation = geometricLoss + atmosphericLoss - groundEffect + barrierLoss
22.2 = 22.2
Calculate Geometric spreading
Geometric spreading = 20 * log10(distanceM / max(1, referenceM))
20 = 20

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