I don't understand. Can you explain why you think having the speaker on the back of the phone is better than it being on the bottom?
A 2nd grader's understanding of physics informs us that yes, indeed, there will be some situation in which the iPhone's speaker is obstructed and another speaker isn't (why, you could stand the phone up!). But what obstruction is going to be more common?
If frequency of obstruction isn't the only issue, what's the compensating virtue of having the speaker on the back of the phone? How valuable is that compensation?
I am not an electrical engineer, but to answer your question it is my understanding that the diameter of a speaker is very important for sound quality, volume, and cost. This is the reason that home audio speakers aren't the size of thimbles.
I did a quick search to see if any of those issues have been talked about wrt iphones, and the top hit was http://forums.macrumors.com/showthread.php?t=761725 ("when i listen at max volume [my iphone] is really bad. my nokia N82 compared is like a audiophile system") -- which I imagine is caused by the N82 having a larger speaker positioned on the back.
Puts the iphone 4 over 3g as ~3x quieter than a nexus s over 3g. (2g is closer, but no one I know uses their iphone 4 over 2g).
From the review: "For a long while, people have complained that the iPhone [3g & 3gs]'s speakerphone volume was too quiet... I'd say the iPhone 4's speakerphone is still loud enough, though calls over 3G are still a bit too quiet. Until Apple increases the gain on 3G calls, iPhone 4 customers who are hard of hearing should invest in a bluetooth headset."
A 2nd grader's understanding of physics informs us that yes, indeed, there will be some situation in which the iPhone's speaker is obstructed and another speaker isn't (why, you could stand the phone up!). But what obstruction is going to be more common?
If frequency of obstruction isn't the only issue, what's the compensating virtue of having the speaker on the back of the phone? How valuable is that compensation?