Wednesday, December 31, 2008

Human Auditory System: Speech Intelligibility overview

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.


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

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

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


Wednesday, December 24, 2008

Forensic Linguistics: Untangling Tricky Talk

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.


Tuesday, December 23, 2008

Optics: Adjustable glasses invented

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

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

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.


CCTV: Work continues on automating CCTV surveillance

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.

Sunday, December 14, 2008

CSI: TV show highlights new fingerprint technology

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!

Tuesday, December 02, 2008

Imaging: Improvements in through-wall radar imaging

StrategyPage has a short article about the two latest versions of through-wall radar imagers (namely the Xaver 400 and RadarVision). These devices allow soldiers and police to see objects, including people, on the other side of a wall made of standard building materials, such as concrete, wood, gypsum board (a.k.a. drywall), and the like, but not metal.

These devices work by emitting an RF (radio frequency) radar pulse, listening for the reflection of that pulse off of objects in the wall and on the other side, and using time-delay (i.e. how long it takes for the reflected pulse to come back) and direction (i.e. which direction did the reflection come from) information to construct a picture. This is similar to how bats and dolphins use acoustic echo location, just with an RF pulse instead of sound pulses.

This is a handy capability to have in hostage and other situations where a team has to enter a building where armed attackers or booby traps might be waiting for them. The engineering problems that had to be solved in order to come up with a deployable system were extremely challenging - my had is off to the teams that did this.


PS. In case you are interested, I posted some time ago about a DARPA (Defense Advanced Research Projects Agency, US Department of Defense) effort that developed a through-wall motion detector which was compact and lightweight - so light-weight that you use it with a single hand, like a stud-finder. That post can be found here.

Sunday, November 23, 2008

Biometrics: Request for automation to reduce FBI backlog

The StrategyPage has a short article on the backlog facing the FBI in analyzing DNA samples - 40,000 samples in the que with a work-off rate of 4 samples per week! Automation will reportedly improve the work-off rate to 200 samples per week.

One data point that would be useful in getting a fuller picture would be the rate that new samples are being added to the que. If anyone has any information on that, please post it in the comments.

The article also gives a brief history of biometrics, starting with appearance (visual) and going through fingerprints (first recognized as unique 4 centuries ago!) and others until the recent methods of gait and DNA.


Saturday, November 15, 2008

Fun: Sew me the music

Gizmodo highlights a sewing machine by SOUNDS.BUTTER that stitches the time-amplitude waveform of the sound.

Sunday, November 09, 2008

Image Forensics: Was North Korean leader's photograph tampered with?

A photograph was released by the North Korean government last week that purported to show Kim Jong-il, their national leader, reviewing military troops - and looking suspiciously healthy after reportedly suffering a stroke. The Times Online and BBC (both center-left UK newspapers) report on the discrepancies in the photograph, including mismatching shadows and a missing black line.

Monday, November 03, 2008

Saturday, November 01, 2008

Physics: A round-up of recent interesting links!

My aplogies for my light posting of late. Outside commitments have kept me from posting nearly as much as I would like. Here is a collection of links that I have saved up over the last several weeks to blog about. I hope you enjoy them, but please note that some of these are not serious, scientific articles - just because it can be found on the Internet doesn't make it science, much less forensic science! If you are particularly interested in any of the topics addressed below, just let me know and I'll delve further in a future posting.

K-Lite codec package update

X-rays made from Scotch(R) tape (hat tip to A.A.)

Superconductivity Can Induce Magnetism

Deaf people feel their way to speech

Seeing Through The Skin: Optic-less Imaging Technology Could Beat Lens-based Imaging Devices

HOWTO read the secret forensic dots in your laser-printer output

Biometric identifcation by body language

Sound-card oscilloscope

Audio bone headphones

Scientists Watch As Listener's Brain Predicts Speaker's Words

Hidden airport scanner will pinpoint terrorists

Overpaid professions

Military camouflage

Police probe cell phones to catch criminals

How magicians control your mind

How forensic lab techniques work

Computers reassemble pieces of fractured archaeology

Review of Microsoft's Photosynth

Images of atmospheric optics

12 worst Photoshop mistakes ever

Darpa super-resolution vision technology R&D

How other senses adjust to blindness

Family name geographical profiler

Tuesday, October 28, 2008

Image Recognition: Military requirements push technology forward

The Strategy Page has an article about how the proliferation of video on the battlefield (e.g. from surveillance cameras and even night vision goggles) is driving technology development. Initially, it was the UK (United Kingdom) that drove image recognition technology with its massive deployment of CCTV in public spaces (e.g. train stations, airports, city centers, and shopping malls). Now, it is the military.

The benefit from computer-assistance in analyzing video comes from the following:

  1. Volume (i.e. the sheer number of cameras and, hence, images to be monitored and/or analyzed)
  2. Concentration (i.e. the human visual system loses the ability to concentrate effectively on images after about 20 minutes of continuous viewing)
  3. Memory (i.e. computers can track and, possibly, predict more things simultaneously than a human can because, generally speaking, computers are not nearly as attention and working-memory limited in the short-term as humans and far outstrip us in their ability to recall video sequences over the long term - they can just play back the video recording off of their hard disks)

The article claims that the abilities of computer systems to recognize patterns is rapidly improving and approaching that of humans - that is no small feat as humans are simply amazing in their ability to perform real-time pattern analysis.

One intriguing point made in the article is that the current conflicts are generating a lot of real-world recordings of "bad behavior" that can be used to train and test new pattern analysis and prediction algorithms - training data like this is like gold to us signal processing types!


Thursday, October 09, 2008

Human Auditory System: Artificial Cochlea

A next generation implementation of an artificial cochlea has been developed by researchers at the University of Michigan and Tufts University (both in the USA). The natural cochlea is the sea-shell-shaped structure in the human auditory system that is the final stage in the conversion of air pressure variations (a.k.a. sound waves) into neural impulses that convey the frequency and amplitude information information contained in the sound to the brain for interpretation.

EDN (USA technical magazine) has an article which contains more technical detail and pictures on the advance.

I should point out that this version of the artificial cochlea is not an exact replica in form factor (i.e. shape) or function of a natural cochlea. For instance, the artificial cochlea is planar in shape versus sea-shell-shaped; covers the frequency range of 4200 to 35,000 Hz versus the 20 to 20,000 Hz of the human ear; and isn't continually fine tuned by an external processor to focus on frequency bands of interest, like the human cochlea does when one is, for instance, one's brain is picking out a familiar voice in a cocktail party situation. I mention this not to detract from their excellent work, but instead to give you, curious reader, reasonable expectations as to its specifications and performance.

Friday, September 26, 2008

Thursday, September 25, 2008

Audio Forensics: New LinkedIn Forensic Audio Group

Phil Manchester (Force Forensic Audio Specialist, West Midlands Police, UK) has just started a Forensic Audio Group on LinkedIn, the popular professional networking web-service. He plans to use it not only as a way to connect people working or interested in this field, but also as a forum for discussions related to it. I have just joined up myself and I encourage you to do the same if you are keen on audio forensics. The basic membership in LinkedIn is free of charge, as is membership in the group.

Wednesday, September 24, 2008

Testimony: Memory is fallible, study confirms

Cosmos (Australian, popular-science magazine) has an article on research by James Ost, University of Portsmouth (UK) into the accuracy of recall, in this case, of video news reports seen some three months prior. There were a couple of interesting statements that popped out at me:
"Ost said that people who were more likely to come up with false memories scored higher on a scale of "fantasy proneness" than those that did not." (My comment - "fantasy proneness" appears to mean "creative" in this context.)

"Ost said that when DNA testing became available in the U.S. in the early 90s, 80 per cent of death row cases that were exonerated, were found to have been wrongly convicted on the strength of mistaken identity."
Although the article doesn't address it directly, previous studies have shown that accuracy of recall also depends greatly on the amount of time that has past since the event, which gives all the more reason to get witness statements soonest.

Image Forensics: Adobe launches CS4

Adobe has launched the latest version of its Creative Suite, which includes, most importantly for image/video forensic types, Photoshop. Headline features of Photoshop CS4 include:
  • GPU-based drawing of documents onscreen (for speed improvements)
  • 64-bit for Windows (but not for Mac OS-X, at least yet)
  • Expanded 3-D paint, lighting and rendering tools
Hat tip: Ars Technica

Tuesday, September 16, 2008

Linguistics: Forensic Linguistics used on text message evidence

Dr Tim Grant, Deputy Director of the Centre for Forensic Linguistics at Aston University (UK), is well known in forensic linguistic circles. ScienceDaily has excerpts from an interview with Dr. Grant following the successful conviction of a murderer that relied partly on Dr. Grant's testimony about text messages allegedly sent by the suspect (since convicted) to throw investigators off the trail. I call your attention to the careful and correct use of the phrases "unlikely" and "more likely" to describe the results of the analysis, instead of a phrase such as "proved conclusively".

In addition, here is a link to a BBC (British Broadcasting Corporation, UK) news story about the case and the analysis of the text message evidence. Very interesting stuff!

Sunday, September 14, 2008

Acoustics: Listenging to nature

Using microphones to capture the sounds made by animals in their habitat, minus humans and their man-made sounds. These sounds are known as the "biophony" and are used to sense the quality and character of the animals' habitat. Wired has the story.

Author's comment: It's a good thing that animals don't have privacy rights in the USA (yet!), or these scientists would be in jail for unlawful surveillance activities!

(Via Cross-Spectrum Acoustics)

Wednesday, August 27, 2008

Acoustics: Science of sound in the sea

Sound requires a medium, such as air, to travel in. Here is a link to a site dedicated to the case where the medium is water. The site belongs to the University of Rhode Island (USA) and it has plenty of information for educators and students about the science of sound and the animals that make underwater sounds, such as dolphins, whales, and fish. I particularly liked the recordings of the animal sounds.

PS. Thanks to C.S. for the link!

Human Auditory System: Perfect pitch is more common than previously believed

It turns out that the ability to identify the pitch of a musical note without needing a reference note to compare to is more common than previously believed. This ability is called "perfect pitch" or "absolute pitch", as opposed to "relative pitch".

Using a testing technique adapted from studies involving infant hearing, researchers at the University of Rochester's Eastman School of Music and Department of Brain and Cognitive Sciences were able to test for perfect pitch in a random sample of people, including people with no musical training whatsoever. In the past, these tests were performed only on people with musical training who could identify notes by name. For more on this study, follow this link.

Saturday, August 09, 2008

Human Auditory System: Tinnitus follow-up

FYI, I added some new information to my recent post on tinnitus. It can be found here.

Friday, August 08, 2008

Admin: Posting will be light

Posting will be light for another week or so while I am on summer holidays. Back soon, when I will be "tan, rested, and ready" for more blogging.

Thursday, July 24, 2008

Biometrics: Fingerprints versus palm prints

While driving back from Charleston, SC (USA) today - a lovely seaport city, by the way - I was catching up on my podcasts and happened to listen to a Wall Street Journal (US, center-right, business news) segment on new palm print readers.  The part that caught my attention was the claim by one interviewee that - and I'm paraphrasing here - "people" were concerned about using fingerprint biometric identification technologies because they were worried about later being falsely accused of a crime due to a mistaken match to a print left at a crime scene.  The interviewee went on to say that as police did not collect palm prints during crime scene investigations, palm print biometrics systems were getting a leg up in the market place.

This made me wonder exactly who are these "people" he referred to?  I'm rather doubtful that it is the general public that has these concerns.  I find it much easier to believe that elements of criminal "society" or privacy advocates would be tuned-in to these issues, but not the average man on the street.  I might be being too critical of this particular piece, but I thought that the reporter should have challenged, or at least followed up on, that statement.

In a larger context, this may unfortunately be a textbook example of how public policy is determined at the chaotic intersection where the general public, subject matter experts, issue advocates, the marketplace, and technology all collide.  I certainly hope not!

Monday, July 14, 2008

Admin: National NATIA conference

I haven't missed many national NATIA conferences over the past twelve years or so, but this year I will unless I can exploit some quantum mechanical effect on a macro scale - I can't be in two places at once. So, I'm off to points south instead of west. Enjoy the conference, you who can attend, and I look forward to hearing about any interesting a/v forensic happenings. Cheers!

Saturday, July 12, 2008

Biometrics: Fooling an age verification camera

Of course, this comes as no big surprise, but it is amusing - a news reporter in Japan used a photograph clipped from a magazine to fool an age verification camera system on a cigarette machine. Link to the Daily Irrelevant post.

Friday, July 11, 2008

Human Auditory System: Experimental tinnitus treatment

Researchers at the University of Arkansas for Medical Sciences (UAMS) have developed an experimental treatment to help sufferers from tinnitus (also known as "ringing in the ears"). They report that they have successfully treated one patient using a technique known as frequency repetitive Transcranial Magnetic Stimulation (TMS). The treatment scheme involves multiple sessions of this magnetic stimulation with the location of the magnet coil being determined from a PET scan, which is an imaging technique used to see inside of the brain.

The ScienceDaily article says that 17 percent of Americans suffer from tinnitus, but I am not sure what that statistic means - is it "suffer from at some point in their lives", "continually suffer from" or what? It seems from anecodatal evidence to be "continually suffer", but that is besides the point. It will be a step forward if they have developed a safe and effective treatment.

Follow-up: I was speaking to an ENT (Ear, Nose, and Throat) specialist the other day and asked about this statistic of 17% of Americans suffering from tinnitus. He said that that statistic was compiled from medical records - in other words, the number of patients that reported tinnitus symptoms to their doctors. I unfortunately did not think to ask him at the time whether the raw data was then adjusted to account for other factors or not. He also said that taking certain prescription medications, such as Cipro, can result in long-term or permanent tinnitus and that the chances increase if the patient has existing hearing loss (presumably age- or exposure-related).

Wednesday, July 09, 2008

Human Speech System: Woman acquires new accent after stroke

ScienceDaily (USA, online research news site) reports on a case in Canada of a woman who developed a new accent after having a stroke. This is a recognized medical condition known as the "foreign accent syndrome". What struck me about this particular case is that
  1. the subject had not been exposed to the newly acquired accent before
  2. the new accent was still in her native language (english)
  3. even after two years of therapy, the new accent persists
I'm not a specialist in brain science, although I do follow it out of curiosity, but it seems to me that this case brings into question exactly how independent or dependent human spoken language accents are on our common brain structures. It seems to beg the question whether the speech-motor area in the brain puts constraints on the formation of accents, and, assuming it does (which seems reasonable), then how much? Is it entirely a matter of coincidence that the damage to her brain resulted in a new, but recognizable, accent? Why not some accent that was unrecognizable? Does the speech-motor area have some type of built-in presets that directly lead to or indirectly influece the development of different accents?

But what does this have to do with forensics, you might ask? Well, for starters consider voice comparison and subject profiling both rely directly and indirectly on understanding how the speech-motor area functions and how accents develop. Fascinating stuff!

Human Auditory System: Beaming sounds into your head

Journalist David Hambling has written in New Scientist (UK, center-left, popular science magazine) and Wired (USA, center-left, popular technology magazine) about the on-going development of a technology to beam sounds into a person's head using microwaves. This technology is not immediately of practical benefit, judging by the articles, but it is a bit of fun reading.

What I took away from these articles is that there are potential (probable?) health risks when used a high power levels, such as in crowd control applications, so researchers are looking at where it might be useful in low power applications - advertising is mentioned, of course.

As an aside, I noticed the continuation of a pattern that seems to appear with all less-than-lethal "weapons" (i.e. those technologies that seek to incapacitate, drive-off, etc, rather than kill the subjects) - namely, once you label a technology or technique as "less than lethal", this seems to consistently bring with it the hard requirement that it be 100% less-than-lethal in all conditions. Taken to its obvious conclusion, this pattern will make most, if not all, less-than-lethal development projects go bust at some point, for better or worse.

Monday, June 30, 2008

Image Forensics: New blog - Forensic Photoshop

There is a "new" (i.e. started this year) forensic blog that goes into some of the nitty gritty details of image forensics. Forensic Photoshop is penned by Jim Hoerricks, who is an experienced practitioner in the field. I've found his posts to be both very interesting and current. Enjoy!

Image Forensics: Augmenting video restoration & enhancement with a forensic artist

The math, science, and technology used in video forensic filtering and forensic video analysis can work minor, and sometimes major, miracles. However, it is not "the be all and end all", as the saying goes. This article in Forensic Magazine uses an actual case to show where a professional forensic artist was able to use knowledge of human physiology and such to generate a full frontal facial drawing of a suspect from a single frame of a security camera video taken at from the standard elevated position. Let's hear it for the liberal art majors!

Tuesday, June 24, 2008

Computer Audio: Pro Tools now available for Mac OS-X Leopard

Pro Tools for Leopard is out. I don't use it myself, but I know several audio forensic professionals who do and they swear by it.

Acoustics: Acoustic cloaking

First there came visual cloaking of tanks, et al. Now, there is a design idea for an acoustic cloak - I should have seen it coming (pun intended)!

Image Recognition: Military uses pattern recognition to detect bomb planting activity

I wanted to call your attention to an article by the Strategy Page on how the US military in Iraq is using pattern recognition on imagery to detect IED (Improvised Explosive Device) emplacement activities.

A very simple implementation of this technique is to take a picture on Day 1, then another picture from the same location and in the same direction on Day 2. Next subtract the two images from each other and see what is left over. All the things that did not change between the two images will disappear and only those things that changed will be left! In this case, what will be see on the "difference image" might be some disturbed gravel, tire tracks off the side of the road (assuming it is a road-side bomb emplacement) or, if the military guys are really lucky, what will be left is a bunch of guys standing around with shovels and a bomb as they work to put it in place. Neat (and helpful)!

Monday, June 23, 2008

Physics: Physics for Future Presidents

I freely admit that I am a geek. However, strange though it seems to me, I am not a gadget freak. That being said, even I was won over to podcasting. A friend got me excited about listening to university courses on-line via podcasts (thanks, Amy!). An iPod Nano and iTunes were my ticket to liberation from over-the-air radio during my travels.

With that small confession and short history out of the way, I got the urge today to share one of my favorite podcast courses with you - Physics for Future Presidents, by Richard Muller. His explanation of the issues and science around global warming alone is worth the cost of an MP3 player. You don't have to use iTunes to download it, but it is convenient if you do. Enjoy!

Admin: Teaching

As mentioned on a previous posting, I am teaching for two weeks - hence the light posting during the last week and, most likely, the rest of this one. I am, however, still moderating comments, so keep them coming!
Best Regards,

Tuesday, June 03, 2008

Audio Forensics: Off to a conference

The Audio Engineering Society is holding its 33rd International conference later this week (June 5-7). The topic is Audio Forensics - Theory and Practice. I'll be there, so if you are able to go, please look me up.

Forensics: New technique recovers fingerprints from bullet casings after firing

Forensic scientists at the University of Leicester (UK) and Northamptonshire Police (UK) have announced a way to recover fingerprints from fired shell casings. The technique involves the use of an electric charge to attract an electrically conductive powder to the minute amount of corrosion caused by handling the shell casing. The act of firing the bullet actually improves the ability of the technique to recover the print. For more information, see this article from Science Daily.

PS. On re-reading my post, I noticed that I did not supply any answer to the obvious question of "so what?". The reason this technique is particularly interesting is that it potentially provides additional forensic evidence that could identify participants in gun crimes. Imagine being able to re-open a "cold case", for instance a drive-by shooting, using nothing more than a spent shell casing (and a fingerprint database, of course). Hopefully, there will not be any hidden "gotchas" in the details and this technique will be able to fulfill its initial promise.

Friday, May 30, 2008

Image Forensics: More on tamper detection

Steve Eddins (Mathworks Inc., USA), writing on his company-sponsored blog on image processing, has an excellent post regarding an article by Professor Henry Farid in the June 2008 edition of Scientific American (USA, center-left, scientific magazine). The article is primarily about tamper detection or, in other words, spotting retouching or "photoshopping" of photographs.

Thursday, May 15, 2008

Image Forensics: How to spot photo retouching

Slate (US, center-left online magazine) has an article (Were the Dove ads retouched? How to spot Photoshop chicanery) on some of the techniques used in identifying if a image has been retouched. In a forensic examination of evidence, this procedure is known as tamper detection. It should be noted that the author, reached out to several experts while researching the topic, including George Reis of Imaging Forensics.


Sunday, May 11, 2008

Image Forensics: New Best Practices Document for Forensic Video Analysis

The committer members over at SWGIT (Scientific Working Group on Imaging Technology) have been very busy lately. Following the recent release of two new sections for review, they have now added another - Best Practices for Forensic Video Analysis. It and other documents can be found be found by following this link.

Human Auditory System: Voice Risk Analysis

The Economist (UK, center-left economics and news magazine) has a short article in the May 8th, 2008 edition on Voice Risk Analysis, which is another name for Voice Stress Analysis or Micro-Stress Analysis. You might recall from my previous posts (here and here) on this topic that I believe voice stress analysis to be a workable interrogation tool, when correctly administered, but then, so again can the copy machine in the hallway - it all depends on whether the subject is, or can be made to be, concerned about it. It is not, however, a lie detector. This author of the Economist's article seems to have come to a similar conclusion.

An interesting point in the article is that, at least in one real-world deployment of a commercial system, the biggest benefit was gained from simply telling the claimants that such a system would be used on them - which caused many to drop their claims prior to being "analyzed" by the system.

Thursday, May 08, 2008

Computer Audio: Latest Audacity beta is released

From the Audacity announcement:

The Audacity Team is pleased to announce the release of Audacity 1.3.5 (beta) for Windows, Mac and Linux/Unix. Changes include improvements and new features for recording, import/export and the user interface. Because it is a work in progress and does not yet come with complete documentation or translations into foreign languages, it is recommended for more advanced users. For all users, Audacity 1.2.6 is a stable release, complete and fully documented. You can have Audacity 1.2.6 and 1.3.5 installed on the same machine.

Saturday, May 03, 2008

Medical: Overview of Synesthesia

Synesthesia is always a popular topic on this blog, judging by the number of hits it gets. In case you don't already know, synesthesia is a medical condition where the stimulation of one sense (such as smell) or cognitive pathway (such as interpreting numbers) gets merged with another sense or cognitive pathway. One commonly occurring example of synesthesia is the seeing of numbers with different colors. For an interesting and informative overview, see this write-up in Interesting Thing of The Day (ITOTD). Enjoy!

Monday, April 28, 2008

Image Forensics: Good Practices

The Scientific Working Group on Imaging Technology (SWGIT) has released drafts of two new "good practices" documents for image forensics, titled "Best Practices for Forensic Photographic Comparison" and "Digital Imaging Technology Issues for the Courts".

These drafts, along with previously released good practices documents from SWGIT and other organizations, can be found on the IAI (International Association of Identification) website at this link.

(Hat Tip: MB)

Sunday, April 27, 2008

Acoustics: Mosquito comes to the USA

You might recall some of my previous posts (here and here) about the Mosquito tone - the high pitched tone that teenagers can hear but adults cannot. It was introduced as an anti-loitering feature in various European CCTV systems. The system operator could activate the annoying tone to drive away "hoodies" from the general area of a security camera in a mall, for example. Teenagers then exploited the technique against adults by making it into a ringtone for their cell (mobile) phones so that (adult) teachers could not hear the ring or text message notification in class.

The latest development is that the security implementation of the technology has undergone another evolutional generation and is being introduced into the US market. The company's Powerpoint presentation provides additional insight, even though one point it makes is entirely inaccurate - the latest version of the Mosquito system measures the ambient sound level and adjusts the level that it plays the annoying tone to be 5 dB (decibels) above the ambient, which, contrary to what the presentation claims, is not the same as being the level of a whisper. I think I understand what they were trying to get across with this point, but the way it is stated is inaccurate and misleading.

This is a controversial, yet ingenious use of technology and biology. We are sure to hear more about this in the weeks and months to come.

(Hat tip: boingboing)

Wednesday, April 16, 2008

History: FBI updates website in preparation for its centinial

The United States Federal Bureau of Investigation (FBI) has updated its website in preparation for marking the one hundredth anniversary of its establishment on July 26th, 2008. They have added some fascinating articles on famous cases of forensic and historical interest. Enjoy!

(Hat tip to Government Computer News)

Monday, March 24, 2008

Forensic Education: Courses for young and old who are interested in forensic audio and video

I've got two announcements regarding forensic education to pass along.

First off, the Department of Justice (USA) is funding Professor Rich Sanders, of the University of Colorado, Denver, to establish a new National Center for Audio/Video Forensics. The full university press release can be found here. It is scheduled to be up and running in the fall of 2009.

Second, 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 from across the state. The reason I mention it here is that I have been asked to teach two one-week runnings of a new course entitled A Mathematical Tour of Forensic Science. If you are interested, you can find out more on their website.

Update: I am informed by the director of the SSP that students from outside of South Carolina are also very welcome to participate.

Monday, March 17, 2008

Image Recognition: "Computer, where did I lay the keys?"

The Daily Mail (UK tabloid newspaper) has a gadget article about Smart Goggles, a human wearable image recognition and recall system built into a set of glasses. The user trains the system by focusing its built-in camera on a series of objects, such as car keys, CDs, etc. while speaking the appropriate name of the object. Once trained sufficiently, the system automatically recognizes images it sees and stores the information for later retrieval, again by spoken word. The processor (computer) is worn on the user's back. The system was developed by Professor Kuniyoshi and colleagues at the University of Tokyo.

It isn't much of a stretch to see how these same concepts could be built into other video applications, such as CCTV systems, for instance. Don't be surprised if they don't work this into a future episode of CSI or similar television show (or the next James Bond movie, for that matter).

Tuesday, March 04, 2008

Optics: "Look Mom, no lens!"

Similar to a child demonstrating how he can ride a bicycle without using his hands, now we have scientists taking pictures without a lens.

Upon reflection, it was a predictable next step. First we had the major advance of refocusing out-of-focus images by, in essence, building a correction lens, all in software. This is what allowed NASA (the USA space agency) to correct some of the Hubble Space Telescope images after it was put into orbit with an out-of-focus optical chain.

But it one can simulate a lens well enough to correct an image, even if imperfectly, why not replace the real lens with a simulated one and focus the unfocused image received by the (lens-less) sensor? That is what the team at Argonne National Laboratory (Illinois, USA) is working on. Of course, simulations are rarely, if ever, as good as the real thing in all aspects, but if for their particular problem (X-ray imaging) the simulated lens is better than their real one, then they will have improved the imaging system and advanced the state of the art yet again.

Friday, February 29, 2008

Forensics: Track where someone has been by analyzing their hair

The Economist magazine (UK) has a short article on how forensic analysis of the chemical composition of a suspect's hair can be used to determine where he has been.

Monday, February 25, 2008

Miscellaneous: More links

Working for a living interferes with blogging - Responsibility is such a cruel mistress.

As you can probably figure out from the intro, I have to give you my sincerest apologies, but work is leaving no time for thoughtful comments or analysis, so here are the links to the raw material that I hoped to turn into interesting posts:

Talk to the machine (Strategy Page)

Listening in with the council's lie detectors (Times Online; hat tip to A.F.)

Music Special: Five great auditory illusions (New Scientist)

Astronomy Technology Brings Nanoparticle Probes Into Sharper Focus (Science Daily)

Wanted: RAM's help in solving crimes (New Scientist) (a YouTube video explaining the attack can be found here)

Snakes Locate Prey Through Vibration Waves (Science Daily)

The 'non-lethal' flashlight (New Scientist Blogs)

Car Camera Recorder Pro: Video of Everything in Your Car's Path (TechnoRide)

Abuse of Auto-Tune
(Cross Spectrum)

Justice Grants will Fund Research at CU-Denver (Business Journal)

FBI wants palm prints, eye scans, tattoos (CNN)

Enjoy! I hope to be back with more in-depth blogging soon.

Monday, February 18, 2008

Indoor Acoustics: Noise in Restaurants

Alexandra Gill writing in the Globe and Mail (Canadian newspaper) has an excellent article about noise in restaurants. Here is a taste (sorry for the pun):

So how loud is too loud?

The ideal sound level for normal conversation is 55 to 65 decibels. When the ambient noise rises to about 70 decibels, you have to raise your voice to be heard. At 75 decibels, conversation is difficult. Above 85 decibels, prolonged exposure - more than eight hours - can permanently damage your hearing.

While restaurant noise levels aren't a threat to hearing loss, "they are certainly an issue for communication. Many, if not most, restaurants have noise levels that are too high for comfortable conversation," says Christine Harrison, an occupational audiologist with the Workers Compensation Board of British Columbia.

I recommend reading the entire article. Enjoy.

Human Auditory System: Echolocation Technique for the Blind is Rediscovered

Perhaps I should have entitled this post "Everything Old is New Again" instead. The Sunday Times of London (UK, center-left newspaper) ran an article recently on how blind British school children are being taught a "pioneering" technique using echoes to help them navigate - just like bats do. The article even mentions Dan Kish and the YouTube video of him riding bicycles on city streets to show that the technique works. Great stuff!

The only problem is that this technique is not new to mankind. It has been used by humans since at least the 1800s, as evidenced by historical accounts of James Holman, nicknamed the "Blind Traveler" for his use of echolocation to travel the world.

Just in case I've lost you by immediately launching into correcting a historic inaccuracy, I will explain what human echolocation is. Simply put, it is the technique of using sound bouncing off of an object (i.e. echoes) to sense where the object is. Blind people have been taught this technique for years, hence the metal tip on the end of the traditional "white cane" used by many blind people over the years to tap the ground as they walked. The technique seems to have decreased in popularity since the widespread introduction of seeing-eye dogs (Note: this is an educated guess based on my own understanding of history, so if I'm wrong, please feel free to correct me!).

Despite the errors in the article and YouTube video, I am excited that this technique is being reintroduced for the benefit of those with impaired vision.

Sunday, February 17, 2008

Noise: Thoughts on quieting a lab

This AP (Associated Press) article about new products on the market for quieting home environments got me thinking about my experiences quieting a few laboratories and what I learned along the way. Here are my thoughts, arranged in no particular order:
  • The frequency of the noise matters. High frequency noises can be reduced or eliminated by light-weight materials such as fiberglass, curtains, carpet, and rubber seals (e.g. around doors). Reducing low frequency noise requires MASS; in other words, it takes heavy materials to absorb the large amounts of sound energy contained in low frequency noise, such as from machinery, engines, air handlers, and the like.
  • Solid-core doors can make a big difference in the amount of sound coming from the hallway (or leaking out into it, for that matter) and cause little, if any, disruption to the work environment when used to replace existing hollow-core doors. Most doors that come standard in home and office environments are hollow in the middle and therefore don't absorb low frequency sounds very well at all.
  • If the room has a drop (also called a "false") ceiling, then replacing the standard ceiling tiles with acoustic ones can make a significant difference and is minimally disruptive.
  • Wall and door treatments, such as barium-loaded vinyl hangings and acoustic panels, offer the benefit of being able to be installed to an existing room without requiring tearing down the walls, but installing them may require significant effort and it will almost certainly be quite disruptive to the existing workspace (think about shelves and such that are on the walls).
  • If you have hollow walls (e.g. gypsum board on stud), then blowing insulation into the wall cavity can reduce middle and high frequency noises without being too disruptive.
  • If full-scale remodeling is an option, consider adding an extra layer of gypsum board or other massive material to the walls. If you go this route, then you should advise the workers to install the boards so that the seams (between boards) of the new layer do not over-lap the seams of the underlying layer. Of course, there may be complications with window and door frames fitting the non-standard thickness of the walls, but a competent carpenter can solve those issues.
  • Speaking of windows, if the building is located in an area where the external noise (e.g. vehicular traffic or aircraft) is an issue, then it will likely make things much simpler if you pick a room without a window for your lab in order to avoid having to acoustically shield it. Likewise, locating away from internal noise sources, such as elevators and air-handlers, is also a good idea where possible.
  • Quieting noises in your lab itself is also a good idea. Computer workstations and other electronic equipment fans are the usual culprits here. A variety of options now exist for quieting computers ranging from low-noise replacement fans to liquid cooling systems that can be added to existing computers.
  • If the acoustic environment is so poor that you need to go beyond the simpler of the measures listed above, then consider getting professional help (i.e. a consultant who specializes in this area) to evaluate the situation and recommend appropriate steps.
  • Choosing a room that isn't a strict rectangular box can be a good idea as it can mean significantly less resonance.
As I said above, my comments are based on my own personal experience on quieting existing rooms. I did not mention options that I am not personally experienced with, such as bass traps. Finally, I have not addressed anechoic chambers or designing sound studios as that is outside of the scope of this post.

Sunday, February 03, 2008

Biometrics: Finger vein scanners being deployed

The use of various biometric technologies to identify individuals as a routine matter of daily life has been slow to catch on, thus far at least. Perhaps it is because there is insufficient demand, perhaps it costs too much (relative to the perceived benefits), or perhaps there are drawbacks with the technologies that have been fielded to implement it to this point.

As far as industry addressing possible technology drawbacks of the equipment, the Guardian (UK, left-wing newspaper) reports that Hitachi has started fielding a new type of biometric technology - finger vein scanners. Finger vein scanners differ from finger print scanners in that they are reportedly more difficult to fool. The principle of operation in similar to the blood oxygenation sensors commonly used in medical settings - i.e. shining a light onto (into) the skin of the finger which is absorbed by the hemoglobin in the capillaries, thereby allowing the imaging sensor to "take a picture" of the capillary pattern. These patterns are reportedly unique to an individual, just like finger prints. Of course, it all depends in how you implement the matching algorithm, but that is another issue - for more, see the Journal of Forensic Identification paper on errors in fingerprint examination.

Whether the scanners address the cost issue I mentioned above remains to be seen. For more details, including one disturbinging case of how a gang got around a finger print scanner to steal an automobile, you can check out the Guardian article.

Thursday, January 31, 2008

Optics: How camera lenses are made

YouTube has a fascinating video segment on how camera lenses are made.

(Hat tip: Gizmodo)

Acoustics: Underwater acoustic modem

An Israeli start-up, Sea-Eye Underwater Ltd., has developed an underwater acoustic modem that is fast enough to transmit real-time video. The reported range of the modem is 100-200 meters (1 meter = 1 yard, approximately).

EETimes has the story.

Monday, January 21, 2008

Image Forensics: An overview

I recently purchased and read the excellent book, Photoshop CS3 for Forensic Professionals, by George Reis and can highly recommend it. Today I came across an overview of image forensics written by him and thought I'd share it with you. The overview article, in an issue of MacTech, can be found here. Enjoy!

Sunday, January 20, 2008

Forensics: Name that codec in one note

Sometimes I feel that I lose track of the founding purpose of this blog - which is to educate people in a non-commercial way about audio and video forensics. In that spirit, I will let the non-specialists among you in on a current trick of the trade - namely, G-Spot. G-Spot is often the first thing a video forensics professional turns to when a piece of digital surveillance video evidence won't play on the laboratory's workstation.

G-Spot is a software application developed by Steve Greengerg to identify what codec is needed to play a video file. Given the plethora of low-cost digital video recorder (DVR) security systems on the market, many, if not most, with their own proprietary codecs, G-Spot can be a life saver. Here is a link to a review of the application (Note: there is some sexual innuendo, but I did not find it to be overly crude).

Now you know what drives many video examiners to distraction every day and what they turn to for the answer.

Brain Science: Train your brain for multi-tasking

As reported by John Tierney of the New York Times (center-left news media, USA), researchers at Wake Forest University and University of North Carolina Greensboro (both in the USA), there may be something to the "Train your brain" fad, at least if you are musical conductor:

The researchers used functional magnetic resonance imaging to map the brains of musical conductors and non-musicians who tried to distinguish musical tones while also being shown visual images. The scans showed that non-musicians had to turn off more of their visual sense than the conductors did in order to focus on the task. One of the researchers, Dr. Hodges, director of the Music Research Institute at UNC-Greensboro, says there are two possible interpretations of the results:

One is that the brains of musicians are wired this way, and that’s why they became musicians. The other is that they train their brains for rewiring. Because conductors have to be able to hear a bad note, then identify who did it, perhaps they rewire their brains to combine their visual and auditory senses. An experienced conductor has trained day after day, year after year, to let their brains pick up various signals from their senses.

The article is quite good and highly worth reading through.

Thursday, January 10, 2008

Miscellaneous: List of links Part 2

How the brain makes a whole out of parts

Humans ARE actually better with one sense than most mammals (namely, fine sound frequency sensitivity)

Adobe Photoshop Elements 6 for Mac is about to be released (and it includes some very neat features for a consumer-grade product, such as Guided Editing and Photomerge)

Telephone companies cancel FBI wire taps over unpaid bills (Not to be a cynic and nothing in particular against The Register, other news outlets, or governmental bodies, but don't be surprised if this hasn't been overblown a bit for political or news making purposes.)

LANL researchers develop low power MRI system (LANL = Los Alamos National Laboratory, USA)

Miscellaneous - List of links for audio geeks

Too much work PLUS too few mentally productive hours EQUALS a list of links without any in-depth analysis. Sorry about that, but I hope to return to blogging more seriously soon. Until then, enjoy these:

Stereo from a single box (Blumlein was an audio genius. If you are an audiophile, I suggest you read a biography on him sometime.)

How the iPhone blew up the wireless industry

Acoustic superlens could mean finer ultrasound scans

Ultra-thin digital voice recorder

Noise reduction technology for cell/mobile phones
(Note that the sales spiel uses words like "crystal" and "pristine" but you can clearly hear artifacting at low levels. Not trying to be overly critical, but couldn't they have let the results speak for themselves without the spin?)