Sound and Light Reflections

Education: Yenka Light and Sound modeling software

2009-06-12T11:15:00.005-04:00

I've been using Falstad's freeware Java applets for teaching acoustics and oscillation concepts in the classroom for years now. I recently decided to give Crocodile Clips' Yenka Light and Sound modeling software a try after some of my own children enjoyed using it in school. At first it was to take advantage of the free license for home use (yes, FREE). Now, however, I'm going to use it in classes thanks to the numerous models already built-in and even more content online. My favorite built-in model so far is "Speed of Sound" - which lets you add other media, such as vacuum, water, and wood, and see how the speed of sound changes and then interacts with the sound wave in air, assuming it exits the extra media at all - very cool!

Not to leave optics out, there are informative models for angles of reflection, refraction, mirrors, lenses, telescopes, and more. For instance, to show that the angle of incidence equals the angle of reflection, the student drags two protractors into the workspace and measures both angles as the (virtual) beam of light bounces off the mirror. Simple, but effective. Many more sophisticated models are available too, plus you can build your own and save them for later use (as an educator, I like that).

Yenka also covers more than the physics of sound and light - mathematics, chemistry, computers, electronics, and other packages are also available. I've tried the chemistry package with my boys. Being boys, they were particularly pleased with being able to experiment with (virtual) dangerous substances after having to suffer through the kid-safe chemistry sets sold in stores these days.

Crocodile Clips is based in the UK, so American and other visitors to their website may not understand the references to terminology used in the British education system. Luckily, the laws of physics do not change as a result of the software leaving the UK! Yenka is a free download for students to use at home. Use outside of the home requires buying a license, of course. Finally, it works on Mac and Windows operating systems.

Enjoy!

Forensic Linguistics: Identify the language of a text

2009-04-29T11:22:00.005-04:00

LangID is a new website that will identify the language of any text you can paste into its webpage or upload/tweet/email them with. This free service is based on the Google Ajax API (Application Programmer Interface) and currently identifies around 85 (human) languages with more being added. A list of the languages that it can identify can be found at this link.

(Hat tip: Good Morning Silicon Valley)

Admin: Summer Science Program in Forensics

2009-04-16T22:27:00.002-04:00

The South Carolina Governor's School for Science and Mathematics (USA) runs its popular Summer Science Programs (SSP) every summer. SSP is a residential summer camp for rising 8th, 9th and 10th graders. I'll be teaching two, one-week runnings of my course, A Mathematical Tour of Forensic Science, again this year. If you are interested, you can find out more on their website. I hope to see you there.

Admin: Posting will be light

2009-03-12T06:40:00.001-04:00

Due to a continuing, heavy travel schedule, posting will be light for a bit longer.

Forensics: US National Academy of Sciences report is released

2009-02-19T06:12:00.003-05:00

DNA evidence was the pebble in the pond, so to speak, for elevating the "science" in "forensic science" - the scientific rigor that has accompanied this new discipline of forensic science continues to ripple through all of the forensic disciplines and our legal system. Of course, DNA evidence was not the only motivating factor, but I do contend that it was the most significant and that the mindset that accompanied its introduction also carried over the other disciplines.

The latest ripple was the release yesterday of a report by the US National Academy of Sciences titled "Strengthening Forensic Science in the United States: A Path Forward". You can read it online or pre-order a print copy at this link.

One should keep in mind while listening to or reading press accounts of this report something that Robert Mueller (physicist, USA) once said, and I'll paraphrase: "Everything reported in broadcast or print media is generally correct, except, that is, for what they report on things that you are actually well versed in, which they invariably get wrong." Such will likely be the case with reporting on this subject.

That being said, how I am interpreting the early press accounts of the report is that this report is another step in this process of bringing the scientific rigor applied to the introduction of DNA evidence into our legal system to all of the disciplines that were already here. In my opinion, this is a worthwhile endeavor. However, we must all be wise enough to understand that we are humans and that any system we create will not be perfect, but if we design the system correctly then mechanisms will be included to minimize and weed out these natural errors while also minimizing the adverse affects on the ability of the system to perform its intended purpose.

Phonetics: The Sounds of American English

2009-02-18T07:37:00.003-05:00

Check out this educational page on the Sounds of American English from the University of Iowa (USA) - complete with cut-away animations of what is happening in the vocal tract and videos of the face during articulation. My wife is probably tired of hearing me point out over the years that this is exactly what is missing from educational software for learning foreign languages. Learning to properly articulate a sound element (phoneme) is so much easier if you know what the articulators (i.e. lips, tongue, jaw) are doing! Well done.

(Hat tip: Good Morning Silicon Valley)

Photography: Automatic panning device for gigabit images

2009-02-08T07:44:00.003-05:00

Engadget profiled the GigaPan Epic some time ago. The Epic is a robotic camera mount that holds your point-and-shoot digital camera and then automatically pans the visual scene, taking picture after picture (up to thousands, according to the manufacturer). Software is included that then automatically stiches the individual images into a single digital panoramic image. Very cool. The inventor used it at the recent inauguration to capture a panorama of the mall. Many more images can be found at a community page devoted to these images. Here is a link to the product page with more details (and the sales price).

Why would anyone need so many pixels in an image? Over the Christmas holidays, the pundits were telling us that no one needs more than, say, 6 megapixels in a camera. Two examples where more pixels are needed include when one needs to zoom in to get small details or when one requires very wide angle shots with good resolution (i.e. which is hard to do with a fisheye lens or a dome mirror).

A potential forensics application is crime scene photography, thanks not only to its functionality, but also its modest cost and compatibility with a wide range of digital cameras.

Enjoy!

Image Restoration: iMovie Stabilization feature

2009-02-08T07:25:00.002-05:00

Despite the best of intentions, I have not yet been able to get around to testing Apple's new iMovie video stabilization feature for the Mac OS (Operating System). I will, however, whet you appetite with a Macworld review I've come across that gives examples.

Enjoy!

Audio Forensics: Solving a Beatles' chord mystery

2009-01-30T13:31:00.003-05:00

Dalhousie University (Nova Scotia) math professor Jason Brown has apparently solved a musical "who-dunnit" - what was the opening chord of the Beatles' famous Hard Days Night? There was an agreed upon suspect - namely George Harrison - but what was the chord? No one could reproduce it, even knowing what guitars they used in performances.

Enter Professor Brown. The professor used tools well known to forensic audio examiners - an FFT (Fast Fourier Transform) to analyze the spectrum and logic. And what did he deduce? It appears that George Harrision had a little help from someone else - perhaps the Beatles' manager, George Martin - who simultaneously played the chord on a piano! So, in the spirit of the board game Clue (Cluedo, for you Brits), it was George AND George, in the recording studio, with a guitar AND piano. Mystery solved!

Here is an article to read more about it. And another one. Enjoy!

(Hat tip to D.E. - thanks!)

Computer Audio: Latest Audacity beta (1.3.7) is released

2009-01-30T11:59:00.003-05:00

Audacity 1.3.7(beta) is available for download. This release primarily seems to consist of bug fixes, but they do say that they added support for DirectSound, which is a widely-used Windows(R) DirectX API (Application Programmer Interface). Here is the text from their announcement:

Audacity (http://audacity.sourceforge.net/) is a fast multi-track audio editor and recorder for Windows, Mac, and Linux/Unix.

The Audacity Team is pleased to announce the release of Audacity 1.3.7 (beta) for Windows, Mac and Linux/Unix. This is primarily a bug-fix release to significantly improve stability and usability, especially on Mac OS X, but includes some new features too.

Cross-Platform Bug Fixes include:

* Muting/soloing caused incorrect channel results in exported stereo files
* Fixes for Nyquist effects, Compressor and Noise Removal
* Fixed Export as WAV could be corrupted if overwriting to same file, and Export Multiple to uncompressed formats only produced 16-bit WAV
* MP3 and WMA now export correctly with all supported metadata

Platform-specific Bug Fixes include:
* Windows Vista: crash opening Preferences
* Mac OS X and Linux: fixes for spurious clipping, label typing, no shortcuts after running effects, and project rate when importing files
* Mac OS X only: fixes for inactive or corrupted menus and hidden dialogues, portable settings, and Command and Control shortcuts. Also FFmpeg installer now available.

New features/other improvements:
* F11 Full Screen mode, high-quality "Sliding Time Scale/Pitch Shift" effect, Audio Contrast Analyzer
* Windows: sound devices can now be opened using the more efficient DirectSound API
* Improved latency correction using fixed correction value

See http://audacity.sourceforge.net/ for details.

Image Recognition: Facial recognition feature in iPhoto

2009-01-28T10:22:00.007-05:00

I installed Apple's iPhoto '09 last night to test how the face recognition feature (called "Faces", of all things) worked. There are nearly 4,000 photos in my personal library, so I left it running overnight while it went through the database and, I assume, ran its face detection algorithm. I then decided to run a test. I manually identified the same person in two different photographs and had iPhoto go out and locate matches, which is its next step in its learning process - the user next needs to confirm or not confirm the identity of each one of the identifications it produces.

So how did it do at the end of this first step? Surprisingly well is the answer, particularly for a consumer-grade product. The raw numbers were 72 correct and 16 incorrect at this first step, but that doesn't tell the whole story. In the instances where it was incorrect, all but three were confused with family members (which admittedly is the most likely confusion outcome since for all pictures with faces in the database, generally at least one is a family member). In addition, it also correctly chose pictures where only one eye was visible, where the age was significantly different, and where there were different emotions clearly visible on the faces. It also did not seem to have a problem with different compression levels, low resolution (including one that was very granulated), face paint, under-exposure, black-and-white, scans (of printed pictures), and color. Finally, it made only one error out of 86 pictures in correctly detecting and locating the face.

So, even though this was not a properly constructed test, the results were more than impressive enough to warrant looking at it further for professional use in some applications.

PS. This is not a product review, per se, but I should say that my experience with this just-released version was not all positive. Namely, it was horribly slow during the step where one has to select a picture, go into the Faces mode, and then type in the subject's name. Each entry took two to three minutes to accomplish, so I saw the "spinning beach ball" that Mac OS-X uses to let you know it is busy quite a lot. Hopefully this bug will get corrected and patched quickly.

Evidence: Listen to the raw audio evidence

2009-01-27T20:58:00.003-05:00

If you would care to listen to the audio and read the transcripts of the Governor Blagojevich (IL, USA) wiretaps, here is the link.

Image Recognition: Facial and license plate recognition news items

2009-01-27T13:42:00.003-05:00

There are two on-line news articles related to image recognition that I would like to bring to your attention.

The first news article is about law enforcement in Tacoma, Washington, USA using a facial recognition package to match 16 years worth of prisoner mug shots with pictures taken by ATM (Automated Teller Machines) in a forgery and theft investigation to generate the lead needed to solve the case.

The second news article is from New Orleans, Louisiana, USA where local law enforcement used a license-plate recognition system to make 20 arrests and recover 23 stolen vehicles and license plates in a 25 day period.

The common thread here is, of course, automatic image recognition. These software algorithms have come a long way in the last decade. However, one should understand that the conditions are partially or completely controlled in both of these applications - i.e. distance, lighting, exposure, aspect (turned toward the camera), and (possibly) compression all fall within acceptable boundaries. In addition, with the license plate recognition problem, the character set and fonts were known in advance. The controlled conditions and a priori knowledge significantly increase the accuracy of the results tremendously and the chances of a successful investigation and prosecution.

(Hat-tip to JUSTNETNews, USA - I highly recommend this free service of the National Law Enforcement and Corrections Technology Center, or NLECTC, which is part of the National Institute of Justice, USA)

Photoshop: Most blatant Photoshopped covers

2009-01-17T18:04:00.005-05:00

I met a graphics artist today whose job is to "Photoshop" pictures for advertisements. We got to comparing stories and she mentioned an incident involving Kate Winslet, the actress, where her legs were slimmed a bit too drastically and caused a stir. Well, before long we were pulling out my MacBook and Googling for that and other instances of "Photoshopped" covers. Here is the best link we found.

Enjoy!

Legal: Recording conversations in the USA

2009-01-17T15:19:00.008-05:00

Michael Flynn's podcast, Legal Lad's Quick and Dirty Tips for a More Lawful Life, gives an excellent overview of the legalities of making an audio recording of someone in the USA when you are not a government agency performing lawful surveillance. When is it legal and when is it not? The short answer is: it depends - on whether there was a reasonable expectation of privacy, what state the conversation takes place in, and whether all parties being recorded gave consent.

For instance, if one is having a loud conversation on the street (a public place), how can one expect privacy from being overheard? If one can be overheard, how can he then complain that a record (or recording) was made of what he said? An example from daily life, that we can all probably identify with, is the standard phrase we hear when we dial technical support or customer service - "All calls are recorded for quality assurance." In other words - "We're recording you - you've been warned". By being advised and not hanging up, you will likely been seen as having given implied consent.

Legal Lad, being a lawyer as well as having good communication skills, gives a more thorough and educational overview of this subject.

Enjoy!

Careers: Profile of a Court Reporter

2009-01-04T07:02:00.002-05:00

The Wall Street Journal (center-right financial newspaper, USA) has an informative profile of court reporting as a career option. One point from the article that caught my eye was that while training takes only two years and salaries are attractive (at least in the USA), one must learn to type at 225 words a minute with 97% accuracy!

Human Auditory System: Speech Intelligibility overview

2008-12-31T14:24:00.002-05:00

A colleague pointed me to the following overview of speech intelligibility on the Sound & Video Contractor website. It was written for intelligibility during teleconferencing, but the information in it is directly applicable to audio forensics. Special attention should be paid to how reverberation and signal-to-noise ratio (SNR) affect intelligibility.

Enjoy!

Business: Cell phone forensic company sells products for "free"

2008-12-31T09:55:00.004-05:00

This is a departure from the main, science and technology thrust of this blog - I want to talk about the business side of forensics. The motivation is to highlight the government-industry partnership that exists in some countries, such as the grant program discussed in this Philadelphia Business Journal article, to push forensic tools and procedures out into the law enforcement community. The company profiled in the article (BKForensics) got into cell phone forensics through a small US Federal Government grant and then grew from there. This is also a great "lesson" for all of you budding entrepreneurs out there!

(Hat tip to Forensic Focus)

Photography: Year's top ten tips and tutorials

2008-12-31T09:45:00.002-05:00

Digital Photography School has an excellent roundup of ten tips and tutorials for this year.

Enjoy!

Forensic Linguistics: Untangling Tricky Talk

2008-12-24T14:29:00.006-05:00

I have a confession to make - I only got an iPod once a friend convinced me of the merits of university course podcasts. I've since become "addicted" to several technical, news, and business podcasts and would not have it any other way.

One of the podcasts I enjoy on a frequent basis is All in the Mind, by ABC Radio National (Australia). Last week's episode was titled "Untangling Tricky Talk" and covered forensic linguistics as well as transcription by deaf people. The forensic linguistic portion was centered around an interview of Paul Foulkes, who gave a very professional account of his discipline.

Enjoy!

Optics: Adjustable glasses invented

2008-12-23T21:27:00.002-05:00

Inventor Josh Silver (UK) has developed a pair of eyeglasses that are instantly adjustable by inflating or deflating a fluid-filled sac in the middle of the optical surfaces.

Read it all on Gizmodo.

Sonar: US submarines get acoustic signal processing upgrade

2008-12-23T20:55:00.002-05:00

The US submarine fleet is undergoing an overhaul of its sonar signal processing systems. Defense Industry Daily has a short article.

Image Forensics: An interview with Hany Farid

2008-12-23T20:46:00.002-05:00

SiliconValley has an interview with image forensics researcher Hany Farid. My favorite excerpt was this:

Farid first conceived of the possibilities of digital forensics while at MIT, waiting in the checkout line at the library. Restless, he picked up a copy of the Federal Rules of Evidence, then started randomly reading. What he saw startled him: Film and digital images were equivalent evidence, in the eyes of the court.
"This just seemed like a bad idea,'' he said. "Not that I'm good at seeing the future — but I could tell this would be a problem."

Of course, susceptibility to tampering is not the only thing to be considered when evaluating the relative merits of digital imagery as evidence, but it is obvious that tampering with a digital copy is easier to do and (possibly) get away with than tampering with film or tape.

Enjoy!

CCTV: Work continues on automating CCTV surveillance

2008-12-23T19:59:00.002-05:00

Wired News has an article about ongoing research at Ohio State University (USA) in automating surveillance using a network of CCTV cameras. Similar research and product development is occurring at many locations around the world, so I suggest viewing this article as a sample of where things are heading with CCTV technology.

CSI: TV show highlights new fingerprint technology

2008-12-14T20:59:00.003-05:00

WLFI Television (Indiana, USA) did a piece about the television show CSI spotlighting a new fingerprint technology developed by Purdue University. The piece says that it was supposed to air last month. Neither the researchers who developed the technology (led by Professor Graham Cooks) nor the company that now owns it (Prosolia Incorporated) saw the script in advance, so there is no telling whether it was accurately represented.

If any of you readers did see the episode and would like to fill us in, please do!