I just got my 2010 Mazda3 GS with comfort package last week. I noticed exactly the same thing about the top defroster. The grid is the same as that in your photos. I did some research and found that the grid is used as the on-glass FM/AM wire grid antenna ("window grid antenna" in the mazda3 specification).

 

I've used the Bluetooth streaming audio quite successfully with my Blackberry 8900 and 2010 Mazda3. I'm actually very impressed with the sound quality and this Mazda/Blackberry combination even supports remote control (play, pause, track forward/back) from the car steering wheel and main console.

Bluetooth has a bandwidth of up to 3 megabits/second which is far above whatever bitrate audio files are encoded at (up to 320 kilobits/second for MP3,for example.) So there should be lots of headroom when streaming without any degradation in quality.

In theory, Bluetooth audio should be of a higher quality (perceived or not) than using a cable from the headphone jack of your iPod or MP3 player to the Aux-in jack on the car. That's because it's kept all digital as opposed to a cable hookup which requires a digital to analog step to go across the cable.

However, the wild card is always the wireless environmental conditions which may not be ideal. In that case, you may end up with poor digital Bluetooth reception that would certainly affect the sound quality considerably.

 

Well said

Yeah that's why I never settled with the simple AUX plug in the console. I was going aftermarket with my stereo anyway so I didn't bother with the Bose setup or anything when I bought the car. Afterward when I installed the radio I yanked out the whole AUX plug assembly and ran my iPod cable in through the opening instead.

But yeah you're not kidding... direct all digital > analog conversions

 

I'd like to yank the AUX plug out of the console too so I can get the Ipod cable through there, what's the trick to getting it out without damaging everything? I was hesitant to just start prying on it............!!

 

Good to know that it's probably just the AM/FM grid, and that someone else found the same thing.

Also, I'm beginning to believe my bluetooth issues are my phone's fault. I have an iPhone, and if it starts to sound scratchy (sounds like the treble is overly tinny and crackly), I reboot my iPhone and it usually sounds okay after that.

As far as the wireless conditions go, could you really run into interference while driving down suburban roads? Could household WiFi networks screw with the audio quality?

I wish I had some other BT devices around that I could try out...

 

Bluetooth operates in a slightly different frequency than one WiFi technology band (2.45Ghz band vs. WiFi's 2.5Ghz band) and operates under several channels, changing channels about 1600 times per second.

Basically, there should be absolutely ZERO interference. And as far as interference with other bluetooth signals the other signals probably aren't close enough to cause a problem, given that Bluetooth is a short range wireless technology, and even if it was the constant channel changing and requirements for pairing would, I would assume, cause for no interference.