Noise level observed


It represents an observation of those acoustic parameters that estimate noise pressure levels at a certain place and time. This entity is primarily associated with the Smart City and environment vertical segments and related IoT applications.

Data Model

  • id : Unique identifier.

  • type : Entity type. It must be equal to NoiseLevelObserved.

  • dateCreated : Entity's creation timestamp.

  • dateModified : Last update timestamp of this entity.

  • location : Location of this observation represented by a GeoJSON geometry.

  • address : Civic address of this observation.

  • name : Name given to this observation.

    • Normative References: []
    • Optional
  • description : Description given to this observation.

    • Normative References: []
    • Optional
  • dateObserved : The date and time of this observation in ISO8601 UTC format. It can be represented by an specific time instant or by an ISO8601 interval. As a workaround for the lack of support of Orion Context Broker for datetime intervals, it can be used two separate attributes: dateObservedFrom, dateObservedTo.

    • Attribute type: DateTime or an ISO8601 interval represented as Text.
    • Mandatory
  • dateObservedFrom : Observation period start date and time. See dateObserved.

  • dateObservedTo : Observation period end date and time. See dateObserved.

  • refDevice : A reference to the device which captured this observation.

    • Attribute type: Reference to an entity of type Device
    • Optional
  • sonometerClass : Class of sonometer (0, 1, 2) according to ANSI used for taking this observation. This attribute is useful when no device entity is associated to observations. It allows to convey, roughly, information about the precision of the measurements.

    • Attribute type: Text
    • Allowed values: one of ("0", "1", "2")
    • Optional

Representing acoustic parameters

The number of acoustic parameters measured can vary. As a result this model prescribes the following attributes to convey the referred parameters:

  • measurand : An array of strings containing details (see format below) about each acoustic parameter observed.

    • Attribute type: List of Text.
    • Allowed values: Each element of the array must be a string with the following format (a list of values separated by the | character): <measurand>| <observedValue>| <description>, where:
      • measurand : corresponds to a term defined at
      • observedValue : corresponds to the value for the measurand as a number expressed in decibels.
      • description : short description of the measurand.
      • Examples: "LAeq | 93.6 | A-weighted, equivalent, sound level" "LAS | 91.6 | A-weighted, Slow, sound level" "LAeq,d | 65.4 | A-weighted, equivalent, day period, sound level"
    • Mandatory
  • In order to enable a proper management of the historical evolution of the different acoustic parameters, for each element described by the measurand array list there MAY be an attribute which name MUST be exactly equal to the measurand name described on the measurand array. The structure of such an attribute will be as follows:

    • Attribute name: Equal to the name of the measurand, for instance LAeq.
    • Attribute type: Number
    • Attribute value: Exactly equal (same unit of measurement) to the value provided in the measurand array.

Representing weather conditions

There are two options for representing them:

  • A/ Through a linked entity of type WeatherObserved (attribute named refWeatherObserved) which will capture the associated weather conditions.
  • B/ Adding weather-related properties defined at WeatherObserved.

Note: JSON Schemas only capture the NGSI simplified representation, this means that to test the JSON schema examples with a FIWARE NGSI version 2 API implementation, you need to use the keyValues mode (options=keyValues).

Examples of use

      "id": "Vitoria-NoiseLevelObserved-2016-12-28T11:00:00_2016-12-28T12:00:00",
      "type": "NoiseLevelObserved",
      "location": {
        "type": "Point",
        "coordinates": [-2.6980, 42.8491]
      "dateObserved": "2016-12-28T11:00:00/2016-12-28T12:00:00",
      "measurand": [
        "LAeq  | 67.8 | A-weighted, equivalent, sound level",
        "LAmax | 94.5 | A-weighted, maximum, sound level",
      "LAeq": 67.8,
      "LAmax": 94.5,
      "sonometerClass": "2"

Open Issues

Standard dictionary for acoustic parameters.