Hi, On Wed, 2010-12-22 at 00:07 +0100, ext Niels Mayer wrote: > These are interesting suggestions and that is a very good link > explaining the issues. Also, I was wondering how the n900 speakers > actually managed to sound so good while being minuscule -- so you're > saying a finite impulse response adjustment has been made?
The N900 speakers are equalized by digital filters. Different filter types and EQ responses are activated based on audio modes. There's actually more processing load in effort to make them loud and audible in high ambient noise and keeping the drive within physical limits and other regulations such as 3GPP (for voice). > But > wouldn't that be different "mid air" versus "on kickstand" versus flat > on table (boundary effect)? The used EQ is a compromise for the positions you mention plus the variation in the listening angle and miniature speaker physical capabilities + product mechanics so therefore usually fairly simple. Equalizing for maximal flatness in one position would cause a lot of attenuation that may not be recovered by the loudness enhancements plus make it much worse on other usage positions. > And that processing overhead can be reduced by plugging-in > headphones or activating stereo output? The 3.5mm headphone/line output has minimal processing for generic playback. It is the policy when the output device is high quality and capable to reproduce the content and/or it cannot be identified. The applications should use 48 kHz sample rate for optimal performance if possible. The earpiece on the other hand is another example of limited output device with strong signal processing applied but it is used mainly for voice. There is also need for processing for the microphone for e.g. video shooting. There the challenge is the extreme dynamics of the acoustical sources. There is this plus much more useful generic information available about the audio system by Nokia in the white paper: http://www.forum.nokia.com/info/sw.nokia.com/id/8c35c902-1269-4c91-a8d6-19e9d716bb2a/Audio_System_White_Paper.html Best Regards, Seppo _______________________________________________ MeeGo-handset mailing list [email protected] http://lists.meego.com/listinfo/meego-handset
