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.