Sunday, June 17, 2007

Audio: Noise Canceling Headphone Review

The NY Times (US, center-left newspaper) has a review of noise canceling headphones just in time for the summer vacation air travel peak. Two entries joined Bose at the top of the list - Panasonic and Audio-Technica. They didn't surpass Bose (which is relatively hard to do in this market niche), but equaled it on performance and beat Bose on price (relatively easy to do!).

Things to note:
  1. Over-the-ear designs provide better noise cancellation.
  2. On-ear designs are smaller (and therefore take up less room in one's carry-on bag).
  3. The article didn't review in-ear earphones, which, in my opinion, offer better noise isolation than noise-canceling headphones and are much smaller, but suffer from not being as comfortable for extended use.
Why should audio forensic professionals be interested, other than just because they are often audiophiles to begin with? The answer is because of their sometimes challenging work environments. Simply put, all audio forensic filtering doesn't occur in pristine laboratory conditions. Then again, if you've ever spent time in many police audio "labs", you know they aren't always pristine in an audio (or any other) sense! I remember being invited into the lab of a federal level audio forensic examiner, which doubled as her office also, by the way. She opened the door and we squeezed into what was obviously a converted broom closet. Talk about resonances right in the speech band! Sigh...

But I digress. Audio filtering sometimes even has to be done in the field, which in urban environments can be quite noisy. So, as you can see, audio forensic examiners and audio technicians both can benefit from noise canceling and noise isolating headphones and earphones.

Wednesday, June 13, 2007

Biometrics: Implications of Pay by Voice commercial service

MIT's Technology Review has an article about the new Pay by Voice commercial service by a company called, surprisingly enough, Voice Pay. Now, I can imagine at least a couple of different general responses you, the reader, might have to this news. The first would be the semi-jaded, popular science devotee's reaction of "gee, that makes sense". The other would be the security-minded skeptic's reaction of "that's got to be so full of holes it will look like Swiss cheese."

Both responses are probably right in some sense, BUT, the devil is in the details, as they say. I'll point out the ones that seem the most obvious to me, without getting too technical.
  1. The system is based around mobile (or cell, for the US readers) phones, which implies more environmental noise than fixed line, compression effects (from coding the voice to use less bandwidth over the air), and possible hands-free use (which means even more noise and a different "sound" to the voice, which could confuse the voice recognition algorithm).
  2. Verifying someone's identity is easier than other recognition tasks (like picking someone out of a crowd). The system has been pre-trained on the person's characteristics and the system architecture is usually better controlled, for starters.
  3. This implementation of identity verification uses voice biometrics as well as call-back to the previously registered mobile number. This allows the fusion of two different types of data, although it is over the same "channel." If the shopping is done on-line, then there is not only multiple types of data, but also multiple channels that the data is passing over, which increases security.
  4. Fooling the system with a voice synthesizer might indeed be possible, but access to the potential victim's mobile phone would be required - as well as log-in details in some cases and 100% spoof rate could not be guaranteed.
  5. The company obviously didn't want to get into the issues surrounding false positive/negative rates and credit card security, but the truth of the matter is that the existing credit card system is not very secure in itself, but the losses to the credit card industry due to fraud are small enough compared to the profits that it isn't worth the effort to them to make it significantly more secure. (Note: Before anyone emails me about credit cards with chip and PIN, please consider just how big the credit card market is and how many traditional chipless cards are out there and will be for many years to come.) The company seems to be assuming that the same rules will apply here - if they succeed in getting into the market in a big way, their losses due to fraud will be easily written off.
There is much more that I could say here, but in the interest of not turning this into a paper by itself, I'll cut it off here. Feel free to email me or post a comment, though.

Optics: Liquid camera lens, no moving parts, now with zoom

New Scientist has an article on a different type of camera lens - it isn't made of glass or plastic, but instead uses the boundary of an oily liquid and water, which can be shaped by an electrical voltage to different amounts of curvature. Liquid lenses are used in some mass market products. The twist here is the ability to zoom. This latest research development still has some issues that need to be worked out if it is to supplant existing commercial technologies for the mass market (i.e. cheap, plastic lenses), but the principle seems to be sound. That bodes well for it finding at least a niche problem to solve.

Tuesday, June 05, 2007

Evidence: Courts feeling their ways through electronic discovery issues

The Economist (UK news and economics magazine; liberal in the classic sense) reports on how the judicial system is learning to deal with discovering evidence on mobile phones, computers, and other digital devices.

Video: Ultra-thin camera fits in shirt button and sees like an insect

MIT Technology Review has an article on an ultra-thin camera that uses a thin compound lens and image recognition software to try to see the way insects do.

Video: Using night vision gear to nab movie pirates

The Reuters Oddly Enough section has an article on how Malaysian cinema staff are catching people video taping new movies in the cinema (presumably to sell pirated copies of). How are they doing it? With night vision googles...

Brain science: Clues to roots of synaesthesia

The Economist (UK weekly news and economics magazine; liberal in the classic sense) has an article on a recent study by Romke Rouw and Steven Scholte of the University of Amsterdam into the biological mechanisms behind one form of the medical condition synaesthesia the causes one to see numbers and letters in color (or colour, as the British spell it).

Computer Forensics: Cooling a hard drive to recover data on a broken hard drive

Here's a computer forensic trick I hadn't heard before - putting a broken hard drive into the freezer or refrigerator might "unstick" it.

Audio: Build your own noise canceling headphones

Headwize has the schematics and explanation.

Audio: Using ringtones to catch leopards

Want a convenient way to catch a leopard? Try using a ringtone of a cow mooing...

Brain Science: Infants are amazing learning machines

Live Science has the results of another study that highlights how fast and flexible learning is for an infant.