User Manual

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User Manual (1.0.14) EasyVR 3 13
auditory noises produced by handling or jarring the device from being “picked up” by the
microphone. Such extraneous noises can reduce recognition accuracy.
4. Distance - If the microphone is moved from 15 cm to 30 cm from the speaker’s mouth, the signal
power decreases by a factor of four. The difference between a loud and a soft voice can also be
more than a factor of four. Although the internal preamplifier of the EasyVR compensates for a
wide dynamic range of input signal strength, if its range is exceeded, the user application can
provide feedback to the speaker about the voice volume (see appendix Error codes).
Audio Output
The EasyVR 3 audio output interface is capable of directly driving an 8Ω speaker. It can also be connected
to an external audio amplifier to drive lower impedance loudspeakers.
Note: Connecting speakers with lower impedance directly to the module may permanently
damage the EasyVR audio output or the whole module.
It is possible to connect higher impedance loads such as headphones, provided that you scale down the
output power according to the speaker ratings, for example using a series resistor. The exact resistor
value depends on the headphone sensitivity and the desired output volume (usually in the order of 1-
10kΩ).
Note: Connecting headphone speakers directly to the EasyVR audio output may damage your
hearing.
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