We acknowledge the support of the U.S. Air Force Office of Scientific Research and the U.S. Office of Naval Research in the development of this toolbox.
Overview
The Modulation Toolbox is a set of Matlab files that allows analysis and modification of narrowband modulation spectra in speech, music and natural sounds. Features include:
- Modulation spectrogram graphical user interface.
- Coherent and incoherent demodulation techniques.
- Command-line functions that are modular and interchangeable.
- Tutorial scripts, example applications and documentation.
- Retained functionality of previous releases.
What's New in Version 2.1? (released September 2010)
The major focus of version 2.1 is coherent modulation analysis. In contrast to traditional "incoherent" methods such as the Hilbert envelope, coherent demodulation explicitly defines and estimates the narrowband carriers (or "fine structure") of a signal in order to compute the modulators (or "envelopes"). With the appropriate constraints, coherent carrier detection guarantees properties for more effective modification (e.g., linear filtering) of modulators and/or carriers.
For example, this coherent modulation speech analysis demo shows that, with the appropriate decomposition, speech intelligibility is represented exclusively by the signal envelopes.
Version 2.1 of the Modulation Toolbox encompasses multiple demodulation algorithms, coherent and incoherent, for comparison in signal processing applications. It is algorithmically similar to Version 2.0 (April 2009) but includes a new set of powerful high-level functions with flexible and easier-to-use interfaces. These functions cover the main capabilities of the toolbox:
- Demodulation (
moddecomp.m). - Modulation spectral analysis (
modspectrum.m). - Modulation filtering (
modfilter.m). - Audio synthesis (
modsynth.m).
These functions, in addition to modspecgramgui.m from
Version 1.23,
are modular and interchangeable for a variety of experimental topologies. Refer to the
user manual (PDF) for details.
Modulation Spectrogram GUI
The modulation spectrogram graphical user interface (GUI) allows you to easily view and modify modulation spectra with various different settings. After modification, you can synthesize and listen to the results. The GUI supports three types of demodulation (two coherent and one incoherent) and allows you to apply masks in the modulation-frequency domain. Click here for screenshots and an introductory tutorial.
Further Reading
Version 2.1 of the Modulation Toolbox grew out of a need for distortion-free and effective modulation filtering. Under the appropriate constraints, coherent demodulation achieves this goal and challenges the conventional Hilbert envelope approaches. For more information, consult the following:
- P. Clark and L. Atlas, "A Sum-of-Products Model for Effective Coherent Modulation Filtering," Proc. IEEE ICASSP, Taipei, 2009. (Link)
- P. Clark and L. Atlas, "Time-Frequency Coherent Modulation Filtering of Nonstationary Signals," IEEE Trans. Signal Process., vol. 57, no. 11, pp. 4323-4332, November 2009. (Link)
- B. King and L. Atlas, "Coherent Modulation Comb Filtering for Enhancing Speech in Wind Noise," International Workshop on Acoustic Echo and Noise Control, Seattle, WA: 2008. (Link)
- Q. Li and L. Atlas, "Coherent Modulation Filtering for Speech," Proc. IEEE ICASSP, Las Vegas, 2008. (Link)
- S. Schimmel and L. Atlas, "Target Talker Enhancement in Hearing Devices," Proc. IEEE ICASSP, Las Vegas, 2008 (Link)
For background on modulation and 2D transforms (like the modulation spectrogram), you can read the modulation tutorial, which originally appeared as a special session at ICASSP 2008.
How to Cite the Toolbox
Use the following format to cite the Modulation Toolbox in publications and reports:
|
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Les Atlas, Pascal Clark and Steven Schimmel, Modulation Toolbox Version 2.1 for MATLAB, http://isdl.ee.washington.edu/projects/modulationtoolbox/, University of Washington, September 2010. |
Download instructions
To get your copy of the modulation toolbox, please read the following license agreement. If you accept the terms of the license agreement, fill out and submit the download form below. The latest version of the modulation toolbox will then automatically be mailed to the email address that you specified.
Note that the toolbox was designed using Matlab R2007b and has not yet been tested on other Matlab versions. Also note that the toolbox uses functions in Matlab's Signal Processing Toolbox.
Modulation Spectral Analysis License Agreement
The University of Washington and Prof. Les Atlas and Pascal Clark give permission for you and your institution to use the Modulation Spectral Analysis software developed at the University of Washington for internal, non-profit research purposes, on the following conditions:
- The software remains at your institution and is not published, distributed, or otherwise transferred or made available to anyone other than institution personnel involved in research or instruction under your supervision.
- You acknowledge your use of the software in publications. In return we will acknowledge your contributions made to our research involving the software.
- You provide Prof. Les Atlas ( ) with feedback on the use of the software in your research and instruction, and that Prof. Les Atlas and the University of Washington are freely permitted to use any information you provide in making changes to the software, and are permitted to have control over when and how new versions of the software will be made available for research and/or commercial use.
- Any risk associated with using the software at your institution is with you and your institution.
To indicate concurrence with these terms and to obtain your copy of the modulation toolbox, fill out the download form below. By submitting the form, you indicate that you agree with these terms. For access to the software on other terms, please contact ventures@u.washington.edu.
If the automatic download does not work, you can get the toolbox directly by sending an email with the terms of the license agreement to . Indicate that you agree with these terms, and include your name and affiliation. You will receive a copy of the modulation toolbox in your email, usually within 48 hours.