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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 authority to filter out sensitive frequencies or divert the data entirely, as required. When filtering occurs, the file-name is appended with 'LPF' or 'HPF' for high-pass or low-pass filtering. Often, the military diverted data will be returned at a later date, much of it modified from the original data, see here for more information on the diversion of hydrophone and seismometer data.

For hydrophones located on low-bandwidth observatories (Cambridge Bay, Brentwood Bay, etc), hydrophone audio files may not be available. In this case, any missing audio data is stored on site to be retrieved yearly, while the observatory will upload the spectrogram files as they are much smaller.

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.

For some applications that employ good error checking, they 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. Often the divert consists of splitting the data into a low and high pass filtered components with the file names appended with "-LPF" or "-HPF", respectively. Sometimes one-half of this diverted is available live, while the other component is withheld for review. Usually that withheld data is returned, after a delay of 3 days to 2 months. Withheld data is usually altered by band-pass filtering, often with decimation or resampling. In rare circumstances, withheld data is returned whole or only the missing LPF/HPF data is returned (this data is not labelled "-LPF" or "-HPF", but it should be). This returned data is not usually compatible with original/non-diverted data. 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

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

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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