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Hardware and Software for Investigating
Animal Acoustic Communication
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Animal Sounds

Avisoft-SASLab Pro Tutorial

Opening sound files from a CompactFlash or Harddisk recorder

The new CompactFlash and Harddisk recorders (e.g. Marantz PMD670, PMD660, Fostex FR-2, Edirol R-1, Sound Devices 722) change the way how to transfer sound recordings into the PC for analysis. Because these recorders already save the sound recordings as common sound files (.WAV, (*.MP3)), the transfer (upload) of the recordings is very simple.

Once the recorder has been connected to the PC via its digital interface (either USB or FireWire), the recorder will appear on the PC as a standard mobile mass storage device (like any other external harddisk). So, there is no difference whether the sound files physically reside on the recorder or on the PC. However, in order to speed-up the sound analysis, it is recommended to copy (upload) the files first onto the computer harddisk (certainly a slow USB 1.1 interface might be too slow for a smooth work flow). Besides of this transfer speed issue, the sound file upload is also strongly recommended for archiving the recordings onto more cost-effective storage media (CD, DVD, external harddrives).

A separate Card Reader interface would be useful for downloading the data from the CF cards in case you are using a recorder with a slow USB 1.1 interface.

Avisoft-SASLab Pro provides various ways to open these .WAV files efficiently (either the original files directly from the recorder or the mirrored files from the harddisk):

Main Window

  • Command File/Open...
  • Command File/Browse...
  • Drag&Drop from the Windows file manager window
  • Command File/Specials/'Next file'; 'previous file' (default keyboard shortcuts Strg+N and Strg+P or the buttons < and >)

Spectrogram Window

These commands will load the WAV file and automatically create a spectrogram of the entire file.
  • Command WavFile/Open...
  • Drag&Drop from the Windows file manager window
  • Command WavFile/'Next file'; 'previous file' (default keyboard shortcuts Strg+N and Strg+B or the buttons < and >)

Real Time Spectrograph Window

The WAV files opened here will be played back continuously (while the real-time spectrogram is displayed). So, this option is useful for scanning longer files. Use the command File/'Transfer buffer into main window' to pick out a sub-section out of the original large file. The Real Time Spectrograph Window is launched from the main window command File/'Real Time Spectrogram...'.
  • Command Record/Start (input from file)...
  • Drag&Drop from the Windows file manager window

Note that MP3 files are not supported by Avisoft-SAslab Pro due to the potential artifacts introduced by the lossy compression algorithm. For processing such compressed files it is neccessary to convert them into uncompressed .wav files. This can be done for instance by using the free Lame/RazorLame decoder.

CompactFlash and Harddisk recorder usually allow to select the sample rate. The sample rate should be adopted to the frequency range of the sounds that you want to analyze (the sample rate should be at least about 250 % of the maximum signal frequency you are interested in). If you are unsure, then you should select a higher sample rate (at the expense of larger file sizes).

Optimizing SASLab Pro for processing large files

If the soundfiles are large, it is useful to optimize the SASLab Pro software for processing speed. The dialog box File/'File Open Settings...' provides a few options that influence the processing speed. The bottleneck is usually the limited data transfer speed of the harddisk. So, installing a virtual RAM disk for the temporay files should significantly accelerate the processing speed. Note that the RAM disk must be large enough to hold all the temporary data (at least twice of the size of the largest sound files that you plan to open).

Due to the limited amount of RAM that the common 32-bit Windows can handle (2 GBytes), it might in some cases be useful to use a 64-bit system. Windows XP Professional x64 Edition in conjunction with an appropriate 64-bit hardware platform with plenty of RAM would allow to install a very large RAM disk that is able to hold even the largest .wav files.

© 2005 Avisoft Bioacoustics

last modified on 03 February 2005