Robert CravottaTechnical Editor Robert Cravotta explores processor and software-processing architectures and the impact they have on system and software development. Relevant architectures include microprocessors, microcontrollers, digital signal processors (DSPs), multiprocessor architectures, processor fabrics, coprocessors, and accelerators, plus embedded cores in FPGAs, SOCs, and ASICs.



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Wednesday, February 28, 2007

Engineering decisions and consequences : cell phones

Feb 28 2007 12:11PM | Permalink |Email this|Comments (2) |


Engineering decisions have consequences. Some of them affect technical issues. Others affect business practices, and still other affect social behavior. In some cases, the effects of engineering decisions are plainly obvious while the cause or reason for those effects seems to elude the general consciousness. Take for example, the apparently universal tendency for people to become overtly rude when they are using a cell phone by speaking too loudly. I did a recent search to see if anyone directly identified a cause of this undesirable, yet widely universal behavior. All I found was speculation of intent as to why people speak too loudly as a form of reaching out for attention, exhibiting a lack of etiquette, having no consideration for the people around them, or for showing off. In other cases, the material I found presented experiments on how the people in the area of the person speaking on the cell phone perceived them. However, none of these sites directly identified a possible root cause.

Other, more technical reasons that are put forth in the collective social wisdom, that is found on the Internet, was that perhaps the phones needed better microphones; they needed to amplify sound better; or that cell phones needed to use better data compression for better audio quality. I have another theory as to why many people speak loudly when using cell phones. Most, if not all, cell phones do not feed your voice back to your ear speaker like a wired or cordless phone does. This subtle, yet important difference is most likely driven by the need/desire to extend the battery talk and standby life of a cell phone for as long as possible. However, this difference can create a mistaken impression in the user that the phone is not picking up their voice and that they must speak up for the badly designed microphone to capture what they are saying.

I have found through personal experimentation that I can successfully carry on a conversation over a cell phone while speaking so softly that I cannot readily hear my own voice. As more people opt out of their land lines and use cell phones exclusively, this social “problem” may peacefully resolve itself because there will be no difference in the voice feedback.

The point of this exercise is to get you thinking about the possible consequences, both technical and social, of the engineering trades you must make in your day to day decisions. The other thing you can do is educate your users when decisions you have to make may create disconnects in expectations, like the voice feedback implementation between wired, cordless, and cell phones. Rather than get mad at the user who is unconsciously trying to accommodate a perceived technical limitation, find a way to teach them how to recognize the difference and behave differently in each context. Until people understand that there is a difference in the voice feedback in their various phones, they are likely to continue to try to inappropriately and unnecessarily adjust for the perceived technical shortcomings of their cell phone.


Reader Comments



at 6/19/2007 10:30:54 PM, Sandeep Saini said:
Excellent



at 11/16/2007 4:00:20 PM, Tom Rodney said:
I am not able to duplicate your experiment of carrying on a cell phone conversation while not hearing my own voice. I find that I have to talk a bit louder than background noise or else the noise canceling features of the microphone, or phone, will mask out my voice completely. I am soft spoken, and on the cell phone, people always complain that I am breaking up, and that they can only hear bits and peaces of what I am saying. I found it odd that this problem followed me around as I changed cell phones and service providers over the last decade. I finally figured out if I talk LOUDER than the background noise, people could here me just fine. The engineering decision to put noise canceling technology into cell phones and systems was a good one at the time, but now that cell phones are so ubiquitous, we can not continue to have everyone’s cell phone require them to talk louder than noise around them, that will just make everyone talk really loud on their cell phones and annoy people. The only engineering solution I can think of at this time is to just turn noise canceling off. That way, when someone is in a place with lots of background noise and they are trying to have a cell phone conversation, the person on the other end of the conversation will have a hard time hearing with all the background noise. The person on the cell phone could talk louder, but that would not stop the background noise coming in, it would just add to it. This is the opposite effect that noise canceling would have. With noise canceling, the louder the cell phone user talked the more the noise canceling algorithm could squelch the background noise. I wish there was an option on my phone to turn off noise canceling. I could then talk normally and be heard on my cell phone. I have not seen any phones with the option to turn this off. I guess it is such a “great feature”, that everyone wants it and so all cell phones come with it.

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