Time Frequency Analysis

Contents of this section: Time-frequency analysis package ver 4.xx

      The Time-Frequency TEOAE analysis package is a unique tool which permits the decomposition of a TEOAE response into time and Frequency components (see the November- January 2002 editorial for more information on the topic). In this context, we have observed that certain TEOAE components "last" more than others. These "more-lasting" components are usually well correlated with the spectral peaks of the TEOAE spectrum. The TF technique aims to unveil a number of relationships which exist within a TEOAE response, such as the relationship between TEOAE peaks and SOAEs, the presence of DPOAEs in the TEOAE response etc.

Editor's note:Since this is a new area of research the software which we offer is presented in a evaluation format. The copy you can download performs exactly the same functions as the original software, but in the TF plotting area shows a "evaluation copy" label. The reasons for such a decision are that we would like to sponsor Dr. Grzanka's future work on TF with your symbolical contributions from buying the TF software.

How to Use the program

      The program contains information divided in the following 5 panels :

  • The data of the tested subject (name, ear, protocol etc).

  • The FORM of the TEOAE response (with visible both traces A, B ).

  • The FORM of the Time-Frequency plane.

  • The parameters of the TF analysis and the ILO record .

  • The TEOAE spectrum.

Figure 1: TEOAE response from a term neonate (well-baby).

Features of the program

      The smoothing and signal analysis parameters are accessible by placing the cursor over the TF parameter panel and then pressing the right mouse key.

  • Selection of TEOAE response on which to perform the TF analysis (A, B, A-B, cross-spectrum etc)

    Figure 2: Selection of the TEOAE signal to analyze .

  • Version 4 of the TF package offers the possibility to use two kernels for the Time-Frequency estimation, namely the Wigner and the Pseudo-Wigner respectively. In the future we are considering the possibility to insert more kernels in order to find the kernel best suited for the TEOAE responses.

    Figure 3: TF Kernel selection .

  • Since the TF kernels generate a number of unwanted cross-terms (see Figure 1) we have developed a new method called regional smoothing , which eliminates them. Usually smoothing 200 times generates results which provide information on the various TEOAE components of interest. If you want to see how much the smoothing routine has eliminated the cross-terms, you can right-click on the TF image and select "negative". This new TF image refers to the areas of the TF plane where cross-terms are present. In theory you should continue the smoothing process until the negative TF image presents very small values (usually in blue color)

    Figure 4: Regional smoothing settings .

    Figure 5: The TF data from Figure 1, smoothed 200 times. Several components are shown (horizontal and declining lines).

    Figure 6: The negative TF representation of the data in Figure 5.

  • Analysis Options, where it is possible to select various TEOAE parameters of interest to be displayed in the TEOAE parameters panel.

    Figure 7: Analysis options table.

  • Display color options: The TF graph is coded according the color table shown at the bottom of Figures 1 and 5. It is possible to change the values of the table to fit your needs. If you right-click over the color-table you should see a menu like in the figure below.

    Figure 8: Color settings of the TF plots.

    By using With this menu, you can change the Maxscale (the signal-range of the table, in order to include weaker or stronger signal components) and the Division (the intensity-step which by default is set at 3dB per color).

HOW to Download the program (FREE DOWNLOADING)

      The available form of the program is as an "exe" file which is blocked by the majority of mail servers , as they consider it  spam. Please use the contact us page to send us your email address . We can then send you the file with the Wetransfer.com services. You will receive an email message and a link from which you can download and save the TF file.

      The downloadable program is in executable form (i.e tf_eval.exe)and does not include an installation routine. When you download it copy it into the subdirectory of your choice something like c:\data\TF

Technical Assistance / Suggestions

      In case you encounter problems or you have suggestions on how to improve the TF analysis package please contact us by clicking here.