CMA ML78f User guide

SOUNDSENSORML78F

USER’SGUIDE



CENTRE FOR MICROCOMPUTER APPLICATIONS

http://www.cma-science.nl

2|ML78fSoundSensorUser’sGuide

Shortdescription

TheSoundsensorML78fconsistsofamicrophoneconnectedviaamicrophoneplug

to the sensor box with an amplifier. The  microphone has a frequency response

between20and20000Hz.

Thesensorissuitedtomeasureanddisplaysoundwaveforms.Italsoworks wellfor

speedofsoundexperiments.



The best sources to use with the sound sensor are tuning forks and musical

instruments.Youmayalsoinvestigateahumanvoiceorawhistle.Whenyouusethe

sound sensor make sure the sound level is in the correct range to produce good

wavepatt erns.Ifthesoundistoo

loud,thewavepatternwillbe“clipped”atthetop

orbottom(resultingindistortionofthesignal).Insuchacas emovethe microphone 

furtherfromthesoundsource,orturndownthevolumeofthesoundsource.

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The Sound can only be connected to special interfaces that support I2C digital

sensors like the CMA MoLab interface. The sensor cable needed to connect the

sensor to an interface is not supplied with the sensor (sensor cables are supplied

withMoLab).

Sensorspecifications

The Sound sensor works as  an analog sensor. The analog signal generated by the

sensoris read bythe connectedinterfaceand isconvertedto adigitalvaluebythe

12‐bit AD converter on the interface. The maximum sampling rate of the sensor is

100kHz.

Collectingdata

The Sound sensor works only with specific interfaces. The sensor will be

automatically detected when c onnected to such an  interface. For detailed

information about measurements with sensors consult the User Manuals of the

interfaceandtheCoach6software.

Calibration 

The Sound sensor is supplied with a factory calibration in %. The Coach 6 program

allowsshiftingthepre‐definedcalibrationifneeded.Theusercalibrationisstoredin

non‐volatileusersensormemory.

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ML78fSoundSensorUser’sGuide|3

Suggestedexperiments

Thesoundsensorcanbeusedinavarietyofexperimentssuchas:

 Measuringsoundwaveformsofdifferentsoundsources:tuningforks,various

musicalinstruments,andavarietyofhumanvoicesounds.

 Demonstratingbeatpatterns.

 Determiningthespeedofsoundthroughairandothermaterials.

 Determiningformants

oftherecordedspeechwaveformsbyusingsoundsignal

analysistools(e.g.FastFourierTransformorLinerPrediction)

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TechnicalSpecifications

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Sensorkind

Analog

(on‐interface12‐bitanalogtodigitalconversion)

Measuringrange ‐100..100%

Resolution 0.05%

Frequencyrange 20..20,000Hz

Maximalsamplingrate 100kHz

Sensordimensions Housing:67x19x19mm

Connection 5‐pinsminijackplug

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4|ML78fSoundSensorUser’sGuide

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Warranty:

The Sound sensor ML78f is warranted to be free from defects in materials and

workmanshipfora period of 12months from thedateof purchase providedthat it 

has been used undernormal laboratory conditions .This warrantydoesnot apply if

thesensorhasbeendamagedbyaccidentormisuse.



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Note: Thisproduct istobeusedforeducationalpurposeso nly.Itisnotappropriate

forindustrial,medical,research,orcommercialapplications.   

Rev. 10/06/2012

CMA ML78f User guide

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