Bone Conduction Microphone/earphone (non Vox)

This unit is a "passive" ( contact piezoelectric type ) sensor based unit .It does not have the audio shaping electronics and VOX operation that the more expensive battery operated Bone Conduction  unit has . It has an outboard PTT switch at the end of a separate  800mm cable that can be attached to the finger by a loop of  adjustable velcro . The moulded silicone earphone unit has a vibration sensor  in a "pimple" of silicone rubber that rests against the hard bony surface of the ear canal , this  picks up the internal vibrations from speech. There is a small sealed unit near the radio plug that contains a single transistor impedance conversion stage to match the piezo microphone to the  radios microphone impedance, the power to run these components is derived from the PTT line of the transceiver.  The radio end  of the other  800 mm cable is terminated in a dual pin plug 3.5mm for the speaker and 2.5mm for the microphone with a pin to pin distance of 10mm  the PTT cable connects with the radio cable near the  two pin radio connector .
The earphone requires a good fit to the ear canal to be effective . It has good received volume and clarity , the transmitted audio is not as high fidelity or level as a good electret mic but is  communications quality but does require good clear speech and volume ( don't mumble!) 
 A good application of technique where by the natural high frequency response of the piezo electric  microphone  is used to shape the received audio ( reduce the high amplitude bass and accentuate the low level treble)  required for understandable speech.


Price $80.00 inc gst   plus postage

Pinfold Health Services Ltd.,1172 Arawa st,Rotorua 3201,New Zealand. ph +64-7-3488850 fax +64-7-3486555

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