P800/P802

White Paper, January 2003

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

P800 Loudspeaker

mono.

 

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.

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