ОT-Expert – is a system for forensic audio investigation – a set of special tools and methods designed for the purposes of forensic audio investigation, text decoding of audio evidence including speech enhancement and processing, speakers’ segmentation and forensic speaker voice identification.

OT-Expert is developed hand-by-hand with practicing forensic audio experts and practitioners during real case examination. There are three main tasks to be solved during forensic examination of speech recordings:

  • speech enhancement and processing;
  • segmentation of conversation with text decoding;
  • speaker voice identification:
    • auditive analysis, critical listening;
    • linguistic analysis of general and segment features;
    • speaker prosodic profile analysis;
    • spectral analysis;
    • phonetic (articulation) profiling of the speaker;
    • pitch statistics analysis;
    • formant statistics analysis.

OT-Expert is the platform that can be used for customization of the audio signal analysis system configuration. All modules for audio evidence authentication can be collected on OT-Expert platform covering all tasks of forensic audio examination.



  • Audio signal playback with adjustable speed and simultaneous video stream playback;
  • Different signal representations: waveform and energy, dynamic spectrogram, cepstrally smoothed spectrogram, LPC spectrogram, dynamic cepstrogram;
  • Intuitive signal navigation interface with segmentation and marking features;
  • signals synchronization;
  • case files navigation;
  • audio files batch processing;
  • system results export (image and textual).


Text decoding:

  • speaker phrases borders marking
  • adding text of the speakrs’ phrase
  • phrases interlay allowed
  • hot keys for pre-set speakers (M1, M2, …, F1, F2, … Non-speech)
  • users’ names for speakers support
  • pauses marking
  • font profiling
  • text templates
  • adding phrases with/without text
  • adding segments with playback pause
  • playback of all speaker phrases for cross-check
  • linguistic marks adjustable lists (segment features)
  • speaker file creation
  • export of the text
  • automation of recording text content automation

Speech suitability assessment:

  • duration of vocalized speech
  • speech-to-noise ratio
  • spectra ratio
  • filtering and processing of speech signals

Filtering and processing

Standard set of band filters and customized FR filters: inverse, spectrum-saving, filtering-by-sample, equalizer are available in the system.

Filtering by noise sample (for example from the conversation pause) allows to check the impact of processing to the voice features under investigation.

Speaker voice identification:

  • dynamic spectrogram and cepstrogram view normalization
  • automatic pitch extractor
  • pitch distributions comparison
  • pitch distribution statistical characteristics extraction and comparison
  • prosodic patterns analysis
  • automatic formant tracks extraction
  • phonemes/articulations marking for the purposes of statistical analysis
  • International Phonetic Alphabet table
  • formants scatter plot
  • histogram of formants
  • formants statistical analysis
  • automatic search of matching articulations

OT-Expert allows:

  • Opening of all existing audio files formats and majority of video files formats supported and converted: 3gp, aac, ac3, amr, ape, asf, au, avi, avm, avs, cda, dat, divx, dts, flac, flv, m4a, mkv, mka, mov, mp2, mp3, mp4, mpa, mpc, mpeg, mpg, mts, nsv, ofr, ogg, ogm, ppk, ra, rm, rmvb, tp, ts, tta, vdr, vob, voc, wav, wma, wmv, wsd. Majority of video formats supported. Audio track extraction and simultaneous audio and video playback.
  • playback of audio with playback speed change;
  • playback video stream together and simultaneously with audio;
  • recording of audio from the sound card (analog inputs, microphones).


  • Unique technologies for forensic audio examination;
  • Professional GUI due to the customers’ feedback;
  • Automatic search of matching articulations;
  • Formants scatter plot;
  • Export of results in textual and graphical form for the expert’s reporting.


The software is protected
by USB dongle;

Installation on multiple workstations is allowed;

The license
is lifetime.


Phone/Fax: +7 (495) 679-19-28

Moscow, st. 5th Kozhukhovskaya, 22, bldg. 1, 15A