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P800/P802
White Paper, January 2003
30
Loudspeaker Characteristics
General
The P800’s built-in loudspeaker is most sensitive to middle and high
frequencies; tones below 400Hz generate distortion instead of bass.
Therefore, sampling frequency for WAV should not be reduced below
16kHz, otherwise the characteristic low frequency sampling ‘ringing’ will
be very distinct compared to that of a more linear system.
Recommended WAV file format for the loudspeaker is 22.050kHz
sampling rate, 8-bit samples and 1-channel (mono).
Recommended MP3 setting for playback over the loudspeaker is 64kbps
mono.
P800 Loudspeaker
Ringtones
The stimuli should be kept around 4 kHz in order to generate high SPL (~90dBSPL@40cm) ring
tones (see frequency response in figure below).
The speaker will accentuate with-in this band and alter the timbre of the ringer tones for
frequencies around 2kHz. E.g. a square wave at 500Hz will not sound the same as a square
wave at 2 kHz as is the case for a more linear system.
Recommendation: Keep the bandwidth of stimuli as narrow as possible.
For discrete signals (~80dBSPL@40cm) the band broadens to 2-5 kHz. These types of stimuli
can be generated at a larger bandwidth as an analogue to the above reasoning.
Stereo Headphone Characteristics
The P800 is supplied with a pair of high quality stereo
headphones.
Recommended WAV file format for playback over the
headphones is 44.1kHz sampling rate,16-bit samples and
2-channel (stereo). Files to this standard are very large –
use WAV only for short bursts of sound.
Recommended MP3 settings are 128kbps stereo.