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Audio Data

Audio data is primarily produced by hydrophones (underwater microphones). A number of hydrophones are producing audio files with sounds at a wide range of frequencies, having applications in seismology, marine mammal studies, ship noise and more.

Given the sensitive nature of hydrophone data, the military has the ability to divert the data as required. Diverted data is then reviewed by military authorities, if it does not contain sensitive recordings it is returned to the ONC archive. Prior to August 2016, instead of diverting the entire frequency range of the data, the military diverted only a low frequency band of the data. When this filtering occurred, the file-name was appended with 'LPF' for low-pass filtering. Once filtered, this data remained in separate frequency bands in separate files, so data returned to ONC was labelled 'HPF' for high-pass filtered. See here for more information on the diversion of hydrophone and seismometer data. Data Search and the DataProductDelivery API provide options for filtering out HPF and LPF files, with the "original data" filter in the data diversion mode options (see the Data Product Options section below, one can also select the HPF or LPF files for download). If you happen to download a dataset that has LPF or HPF files and you want to segregate the files, follow these instructions: How to remove LPF and HPF data from an acoustic data set.

For hydrophones located on remote observatories with limited internet bandwidth (Cambridge Bay, Brentwood Bay, etc), live hydrophone audio files may not be available. In this case, any missing audio data is stored on site to be retrieved during regular maintenance (yearly or less). Live the spectrogram data (FFT) files will normally be available they are much smaller and can be sent over limited connections.

When requested format of audio data already exists in the archive, the search will complete immediately, otherwise some processing will occur to convert the formats. Processing times vary, but in general, expect it would take approximately 15 seconds to process one 5 minute file, so one hour to process a day's worth of data.

Some software applications that employ good error checking may reject some of our wav files for erroneous header information. The cause of this is in the military diversion drivers and is outside of ONC's direct control (they hardcoded these values). Only a select few customized applications will reject the files. Audacity, MATLAB and many others read these files fine. If you get an error like this: 

and you are an active MATLAB user, you can fix the wav files with with this MATLAB code: oncwavfilefix.m and it's dependency: wavchunksizefix.m. If not, please contact us and we'll be happy to help.

Oceans 2.0 API filterdataProductCode=AD

Revision History

  1. 20100217: Hydrophone files initially made publicly available
  2. 20130123: searches handled by MATLAB search to process data on the fly if needed; all formats made available to all devices

Data Product Options

Hydrophone Channel

For hydrophone data products only (audio and spectrogram data) on the hydrophone array devices only:
H1

This option will cause the search to return results for hydrophone channel H1 only. The hydrophone arrays consist of multiple hydrophones connected to a single data acquisition computer, which collects the data into single files that have multiple channels (nominally raw hydrophone array files, although other formats can handle multiple channels). Data products may be produced from these files on a per channel basis and returned as specified.

This is the default option.

Oceans 2.0 API filterdpo_hydrophoneChannel=H1

File-name mode field

'H1' is added to the file-name when the hydrophone channel option is set to H1, i.e. IOS3HYDARR02_20111211T152404.000Z-spect-H1.pdf.

H2

This option will cause the search to return results for hydrophone channel H2 only.

Oceans 2.0 API filterdpo_hydrophoneChannel=H2

File-name mode field

'H2' is added to the file-name when the hydrophone channel option is set to H2, i.e. IOS3HYDARR02_20111211T152404.000Z-spect-H2.png.

H3

This option will cause the search to return results for hydrophone channel H3 only.

Oceans 2.0 API filterdpo_hydrophoneChannel=H3

File-name mode field

'H2' is added to the file-name when the hydrophone channel option is set to H3, i.e. IOS3HYDARR02_20120801T090939.000Z-H3.mp3.

All

This option will cause the search to return results for all available hydrophone channels.

Oceans 2.0 API filterdpo_hydrophoneChannel=All

File-name mode field

'H1', 'H2', 'H3', etc are added to the file-name.

Hydrophone Data Diversion Mode

For hydrophone data products only (audio and spectrogram data):

Hydrophones that have both low and high frequency sensors will have the data acquisition mode option while the other hydrophones will have the data diversion mode option.

Diversion Mode

For security reasons, the military occasionally diverts seismic and acoustic data. Over time how this diversion is performed has changed. Currently, when diverted the entire data set is removed.  Diverted data is then reviewed by military authorities, if it does not contain sensitive recordings it is returned to the ONC archive.

Prior to August 2016, instead of diverting the entire frequency range of the data, the military diverted only a low frequency band of the data. When this filtering occurred, the file-name was appended with 'LPF' or 'HPF' for high-pass or low-pass filtering. Sometimes one-half of this diverted was available live, while the other component was withheld for review. Usually that withheld data was returned, after a delay of 3 days to 2 months.  Once filtered, this data remained in the LPF/HPF frequency bands.

Data diversion is further explained in the data diversion page.

Original Data

This option will cause the search to return results for original data only. Files labelled with "-HPF" or "-LPF" are excluded as well as any files that overlap in time with "-HPF" or "-LPF" files. For spectral probability density plots and spectrograms, 'Data Diversion Mode: Original Data' will appear in the plot title.

This is the default option.

Oceans 2.0 API filterdpo_hydrophoneDataDiversionMode=OD

Low Pass Filtered

Applies to pre-August 2016 data only. This option will cause the search to return results for diverted data that has been low pass filtered only (only files with "-LPF" in the their file-names). For spectral probability density plots and spectrograms, 'Data Diversion Mode: Low Pass Filtered' will appear in the plot title.

Oceans 2.0 API filterdpo_hydrophoneDataDiversionMode=LPF

High Pass Filtered

Applies to pre-August 2016 data only. This option will cause the search to return results for diverted data that has been high pass filtered only (only files with "-HPF" in the their file-names). For spectral probability density plots and spectrograms, 'Data Diversion Mode: High Pass Filtered' will appear in the plot title.

Oceans 2.0 API filterdpo_hydrophoneDataDiversionMode=HPF

All

This option will cause the search to return results for all data. For spectral probability density plots and spectrograms, 'Data Diversion Mode: High Pass Filtered' will appear in the plot title. This is only way to see data that overlaps in time with files labelled "-LPF" or "-HPF".

Oceans 2.0 API filterdpo_hydrophoneDataDiversionMode=All


File-name mode field

"-LPF" or "-HPF" is added to the file-name when the quality option is set to high or low pass filtered data, i.e. ICLISTENHF1234_20110101T000000Z-HPF.wav. For spectral probability density data products, 'All' may be added to the file-name, as these plots can join LPF, Original and HPF data together into one plot if the spectral frequency bins are the same (data with different frequency content will make addition plots with labels indicating the frequency range). For brevity, 'Original' does not get added to the file-name.

Acquisition Mode

For hydrophones operating with a duty cycle that includes high and low frequency sample rates. The low sample frequency data will likely have a sample frequency of 16 kHz and the high sample frequency data will likely have a sample frequency greater or equal to then 128 kHz.

Low Sample Frequency

This option will cause the search to return results for the low sample frequency data only (files with "-16KHZ" in their file-names). For spectral probability density plots and spectrograms, "Data Acquisition Mode: Low Frequency" will appear in the plot title. 

Oceans 2.0 API filterdpo_hydrophoneAcquisitionMode=LF

High Sample Frequency 

This option will cause the search to return results for the high sample frequency data only (files with "-128KHZ" or similar in their file-names). For spectral probability density plots and spectrograms, "Data Acquisition Mode: High Frequency" will appear in the plot title. 

Oceans 2.0 API filterdpo_hydrophoneAcquisitionMode=HF

All

This option will cause the search to return results for both the low and high sample frequency data or other mode data. For spectral probability density plots and MAT files, the low and high frequency data will be segregated regardless of option. 

Oceans 2.0 API filterdpo_hydrophoneAcquisitionMode=All


File-name mode field

The sample frequency is added to the file-name for each data acquisition mode option, i.e.  ICLISTENHF1234_20110101T000000Z-16KHZ.wav. There is a device attribute on devices with a duty cycle that links the low frequency (LF) and high frequency (HF) acquisition modes with the exact file-name mode modifier string - if this link is not correct, the data acquisition mode option will not properly filter the data products.

Format

Hydrophone data is available in WAV and MP3 audio files. For normal hydrophones, WAV files are the base data type, for hydrophone arrays, HYD files are the base data type. MP3s are generated from WAV files and are stored in the archive or may be generated on the fly.

For WAV format data, the files will be accompanied by a calibration file (except for FileDownloadService requests). This file is a text file, comma delimited with one descriptive header row. It is named following the usual standard and ending with '-hydrophoneCalibration.txt'. The dateFrom / dateTo is taken from the calibration date range of the first sensitivity bin attribute. If a search extends over multiple calibrations, multiple files will be produced. A currently applicable calibration will produce a file named with a dateTo that is midnight tomorrow. Here is an example of the first few lines of a hydrophone calibration text file:

#Hydrophone calibration sensitivities. The file contains one header line followed by comma delimited data. First column is the centre frequency of each frequency bin(Hz). Second column is the sensitivity calibration for each bin (dB/uPa). Data is from device attributes: http://qaweb2.neptune.uvic.ca/DeviceListing?DeviceId=1230 . Device attribute HydrophoneSensitivityVectorPart1 last modified: 02-Dec-2015 20:59:52. File created: 29-Mar-2016 15:36:06.
1, -33.1853
2, -30.6233
3, -29.8957
4, -29.6103


Oceans 2.0 API filter: extension={wav,mp3,flac}

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