Monitoring programme: Energy, including underwater noise 
Programme topic: Underwater noise

​table of contentS

Regional coordination

Purpose of monitoring

Monitoring concepts table

Assessment requirements

Data providers and access




The coordinated regional monitoring sub-programme was approved by HOD 54-2018. The monitoring of the sound pressure level of continuous low frequency anthropogenic sounds in the Baltic Sea sub-regions is done by each Contracting Party although coordinated by EN-Noise.  

  • Common monitoring guidelines: ambient noise.

  • Common quality assurance programme: missing. National QA/QC exists.

  • Common database: to be considered at HOD 55-2018.


Follow up of progress towards:

Baltic Sea Action Plan​ (BSAP) ​ ​​Segments​Maritime activities
​Ecological objectives​​Viable population of species
Safe maritime traffic without accidental pollution
Marine strategy framework directive (MSFD) ​ ​​Descriptors​​D11 Underwater noise
​Criteria (Q5a)
​11.2 Continuous low frequency sound
​Features (Q5c)
Other physical disturbance:
Underwater noise (e.g. from shipping, underwater acoustic equipment).
Other relevant legislation (Q8a)
​OSPAR Convention


Assessment of: (Q4k)

temporal trends, 
spatial distribution

Human activities
causing the pressures
Effectiveness of measures

Scale of data aggregation for assessments: (Q10a)
HELCOM assessment unit Level 1: Baltic Sea
​HELCOM assessment unit Level 2: Subbasin
HELCOM assessment unit Level 3: Subbasins with coastal and offshore division​
HELCOM assessment unit Level 4: Subbasins with coastal WFD division
Other (specify): Noise sensitive areas or areas occupied by noise sensitive species


Q9a (Q5c)
Q9a (Q5c)
Q9c, Q9d
Q9e, 9f
Q9h, 9i
Spatial resolution
Q9g, 9i
Link to HELCOM core indicatorsLink to
MSFD GES characteristics

Spatial scope
Monitoring started
CPs monitoring
Sound pressure level
Intensity and temporal frequency of underwater noise
National methodology based on BIAS standards
Single point positions in national EEZ for measurement and whole Baltic Sea in the soundscape maps
Pre-core indicator 'Continuous low frequency anthropogenic sound'
11.2 Continuous low frequency sound
Denmark, Estonia, Finland, Germany, Latvia*, Lithuania*, Poland, Sweden

*Will likely start monitoring during 2018-2019.

Brief description of monitoring


​Element / parameter
Sound pressure level / Spatial and temporal distribution 
​MethodVertical column sampling, Gear: WP2, 100µm (90µm), formalin preservation, Kott subsampling, Stempel pipett,
Underwater acoustic sensors are used to convert acoustic energy in water to electric energy. Different systems such as autonomous loggers or cabled real time stations can be used for measuring, recording and analyzing underwater acoustic signals. A typical system consists of a hydrophone, an amplifier, a filter unit, an analogue to digital converter and a data storage media. Usually for autonomous loggers, these are bought as a single unit. For guidance on technical specifications of equipment, methodology for measurements including deployment, signal processing and data handling, see HELCOM Guidelines for monitoring continuous noise.
QA/QC​Measurements are done on a standardized way according to HELCOM Guidelines for monitoring continuous noise. Quality control is done nationally on all data before uploading it to the data-sharing platform.
The data from the national measurements (i.e. processed data) and if produced, soundscape maps, are aggregated to monthly and annual averages. Other temporal resolutions might be considered if appropriate.
Spatial ScopeMonitoring is performed by Member States in their EEZ to capture the local soundscape. The modelled soundcape maps would cover the whole HELCOM area.
Spatial resolution
Minor monitoring is performed at selected (by Member States) prioritized locations in Member States EEZ, covering all Baltic Sea subbasins. Major monitoring is performed at a greater number of stations decided based on the data request by the soundscape modell to be updated.



Monitoring requirements and gaps

Monitoring is to be carried out to fulfill assessment requirements of HELCOM ecological objectives that are specified through HELCOM core indicators. The requirements on monitoring can include number of stations, frequency or sampling and replication.

Underwater continuous low frequency sound, including the pressure from anthropogenic sound on the marine environment, may be directly monitored through in situ acoustic measurements of noise or by acoustic modelling. In order to assess the pre-core indicator on ‘Continuous low frequency anthropogenic sound’, an annual Minor monitoring at prioritized locations in Member States EEZ,
covering several Baltic Sea sub-basins, will generate data of the local sound pressure level. A Major monitoring effort with extensive field measurement programme (for an example, see Nikolopoulos et al. 2016) is done with several years interval replacing the Minor monitoring that specific year. These time intervals are determined by the need for extended monitoring efforts based on the difference between yearly observed and if possible, modelled results, or by the need for specific actions or results dictated by HELCOM processes.

Collected data are processed, quality controlled and sent to the data sharing platform and later visualized in the soundscape planning tool which is a shared resource and financed jointly within HELCOM. The frequencies which must be reported, based on the MSFD Descriptor 11, criteria 11.2, are the 1/3 octave bands 63 and 125 Hz. However, the inclusion of other relevant higher frequencies
are recommended, such as the 1/3 octave band of 2 kHz. HELCOM may decide for additional frequency bands to be monitoried and reported. To analyse any trends in the data, the reported data should be monthly and yearly averaged of the sound pressure level for the decided frequency bands.

If soundscape maps are produced and added to the tool, the user can visually study the sound pressure level at any specific location in the Baltic Sea and compare results defined by different time periods, various noise frequencies, and statistical measures. The maps can be used in a regional assessment together with maps of noise sensitive areas derived from biological data on noise sensitive species. These combined maps can be used to set environmental targets for underwater noise.
In order to understand the temporal and spatial variation in sound pressure, long term data series and a suitable spatial coverage of monitoring is required. The monitoring of ambient noise started for most HELCOM Member States through the BIAS project which produced measured and modelled data for 2014. After that, the measurements have continued at some scale for several Member States although not in the suggested Minor monitoring scale. Some sub-regions have only recently gained a monitoring station. In addition, these monitoring efforts have not been coordinated, creating uncertainties in the use of the developed standard and quality control. No data has been shared on a regional scale since the end of the BIAS project and only one year of soundscape maps at Baltic Sea scale exist (2014), no new maps have been produced. The lack of coordination, too few measurement stations and soundscape maps have created a knowledge gap in the understanding of the temporal and spatial changes in continuous underwater noise and thus, affecting the assessment of the pressure. The suggested monitoring sub-program for the future will reduce the uncertainties in the predictions of the sound pressure level in the maps. The monitoring sub-program will also allow for a reliable input of measured data resulting in scientific
conclusions based on a solid knowledgebase and as a consequence, the assessment of the pressure will be done with less uncertainties.


Adequacy for assessment of GES (Q5d)

Monitoring should provide adequate data and information  to enable the periodic assessment of environmental status, and distance from and progress towards GES as required by MSFD under Article 9 and 11.

​Adequate data?​

Established methods for assessment?

​Adequate understanding of GES?

Adequate capacity to perform assessments?

Assessment of natural variability (Q5e)

Data providers and access

​Data access point
​Not decided
Data type (Q10c)
Processed datasets​
Modelled data
Data availability (Q10c)​

​Data access (Q10c)
Open access​
​INSPIRE standard (Q10c)

When will data become available? (Q10c)
To be decided
Data update frequency (Q10c)
Describe how the data and information from the programme will be made accessible to the EC/EEA​Processed data will be available from the soundscape planning tool. Raw data might be restricted due to national legislation
​​Contact points in the Contracting partiesContact point to national monitoring programmes will be added
​Has the data been used in HELCOM assessments?



  • Dekeling, R.P.A. and et., al. (2014. Monitoring Guidance for Underwater Noise in European Seas, Part I: Executive Summary. s.l. : JRC Scientific and Policy Report EUR 26557 EN, Publications Office of the European Union, Luxembourg, doi: 10.2788/29293, 2014. 
  • Nikolopoulos, A., et al. BIAS Implementation Plan - Monitoring and assessment guidance for continuous low frequency sound in the Baltic Sea. s.l. : BIAS LIFE11 ENV/SE/841., 2016. 
  • Verfuß, U.K., et al. BIAS Standards for noise measurements. Background information, Guidelines and Quality Assurance. Amended version. 2015. 
  • Betke, K., et al. BIAS Standards for Signal Processing. Aims, Processes and Recommendations . s.l. : Editors: Verfuß U.K., Sigray P., 2015.