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The Forensics Menu

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  • The Forensics Menu

    The Forensics Menu
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    The Forensics Toolbar Surveillance, two-way radio, noisy telephone communications and black-box analysis place special burdens on noise reduction software. The DC Forensics10 Audio Laboratory comes complete with a special set of filters and measurement tools aimed at Forensics applications that can be found under the Forensics Menu. Besides being useful in Forensics applications, these filters can be used for a variety of non- Forensics related material. The DC Forensics Audio Laboratory version has a more extensive and higher performance feature set in this regard compared to its more commercially driven DCArt10 counterpart. Certain Forensics filters require more experience to use compared to the others. They are placed under a special category within the Forensics suite called “Advanced Filters” and include the Time Domain Adaptive Filter (TDAF), the Dynamic Spectral Subtraction filter (DSS), the Polynomial Filter and the Spectral Filter. These more advanced filters can all found as a sub-group under the following icon:

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    Click on the down arrow on the right side of the icon to expand the menu.

    In General, noise encountered in Forensics applications can be divided into several basic categories:
    • Out-of-band noise:
    This type of noise is rejected with the brick-wall band-pass
    filter.
    • In-band repetitive noise at a level lower than the target signal:
    This type of noise is rejected with the brick-wall band-stop
    filter.
    • In-band random noise at a level lower than the target signal:
    The standard Continuous Noise filter found under the Filter menu rejects this type of noise.
    • In-band repetitive noise at a level equal to the target signal:
    The Adaptive filter set up for the Keep Residue mode of operation can attenuate this type of noise. If this noise is in the form of a “buzz” you should also consider trying the Harmonic Reject filter found under the Filter menu.
    • In-band random noise at a level equal to the target signal:
    This type of noise can be reduced by using the Adaptive filter set up for the Normal (random) mode of operation or the DSS.
    • Subsonic noise which can’t be heard, but are important events:
    This type of noise can be visualized using the Subsonic Explorer function and is time correlated to the primary source signal.

    Several of the Forensics filters can also be used in those extreme circumstances such as when the noise level is significantly greater than the “good” signal level. In this instance, the ability to hear and understand the underlying speech is typically the goal – not a complete restoration. See the Notes below.

    Note 1:
    It is important to note that the Forensics filters are not optimized specifically for "high fidelity" applications, but more for improving the intelligibility of speech or the discernment of subtle sounds buried in noise.
    Note 2:
    The Diamond Cut Forensics Filters perform best on files that are sampled at 44.1 kHz or higher. If your native file is encoded with a lower sampling rate, up-convert it first before using the Diamond Cut Forensics Filters. While this will not improve the bandwidth of the signal, it will speed up filter processing time.

    "Who put orange juice in my orange juice?" - - - William Claude Dukenfield
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