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INNOVATIONS IN PRACTICAL W ORK: SEISMOLOGY
SEISMOLOGY:
DOWNLOADING AND USING THE AUDACITY SOFTWARE
Audacity is free, open-source software for recording and editing sounds. This leaflet explains how the
software can be used to record and analyse data obtained from the seismology practical kits that the
Science Enhancement Programme has developed. Further details of the activities can be found in the
SEP publication Seismology, which is part of the Innovations in Practical Work series. For details on
how to obtain the publication and the practical kits, see the information at the end of this leaflet.
INSTALLING THE AUDACITY SOFTWARE
The Audacity software can be downloaded from:
http://audacity.sourceforge.net/
Got
ot
he‘
Downl
oads’pageandcl
i
ckon the link to
the latest stable version (at the time of writing, this
was version 1.2.6).
Save the executable file (audacity-win-1.2.6.exe) to
your local drive. Double-cl
i
ckont
hef
i
l
e’
si
conand
follow the installation instructions in the series of
dialogue boxes.
Note that Audacity is available for Windows,
Mac OS X, Linux/Unix. This instruction
leaflet is written for the Windows 1.2.6
version. There may be some variations for
users of other platforms or for different
versions of Audacity.
Open the Audacity software. You should see a window like this:
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INNOVATIONS IN PRACTICAL W ORK: SEISMOLOGY
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THE SEISMOLOGY PRACTICAL KITS
There are three seismology practical kits that can be used with the Audacity software:

 vibration detector

 seismometer modelling kit

 sound source locator
Each of these is described in turn. Often the software will work first time with the kits without any
further adjustments to your computer settings. However, if you do not get the correct kinds of traces
when the software starts recording, then look at the Troubleshooting section at the end. This gives
some advice about making adjustments to your settings.
USING AUDACITY WITH THE VIBRATION DETECTOR
Connect the plug from the vibration detector into the
extension lead supplied with the kit. Plug the
extension lead into the microphone socket of the
computer.
Cl
i
ckont
her
ed‘
Recor
d’
but
t
on.
A new recording display should automatically open –tapping on the table near the vibration detector
should produce a trace similar to this:
Whi
l
ei
ti
sr
ecor
di
ng,t
her
ed‘
Recor
d’but
t
onappear
s
‘
pr
essedi
n’
;i
nt
hi
smode,y
oucanei
t
herpauset
he
recording (blue button) or stop the recording (yellow
button).
If you pause the recording you can continue by
pressing the pause button again. If you stop the
recording, you can then close the recording display
bycl
i
cki
ngt
he‘
X’i
nt
het
opl
ef
tcor
ner
.(
Not
et
hat
you cannot close the display while a recording is
paused.)
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INNOVATIONS IN PRACTICAL W ORK: SEISMOLOGY
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USING AUDACITY WITH THE SEISMOLOGY MODELLING KIT
The seismology modelling kit uses the same coil-and-magnet arrangement as the vibration detector.
The instructions for setting it up are therefore the same (see previous section), though the signal
produced by the modelling kit may look a little different from the display shown above.
USING AUDACITY WITH THE SOUND SOURCE LOCATOR
Recording the signal from the sound source locator
is similar to the vibration detector (see earlier
section) but with one exception: the sound source
locator consists of two microphones and so Audacity
must be set to record in stereo.
Fr
om t
he‘
Edi
t
’
menui
nAudaci
t
y
,sel
ect
‘
Pr
ef
er
ences’
;ont
heAudi
oI
/
Ot
ab,uset
hedr
op
down menu to select stereo recording.
Whent
he‘
Recor
d’
but
t
oni
spr
essed,anew
recording display opens showing two channels. The
example below shows what happens when someone
claps their hands nearer one microphone than the
other –the amplitude on the first channel is greater
than the second.
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INNOVATIONS IN PRACTICAL W ORK: SEISMOLOGY
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To analyse the signals, it is much easier if the units
ar
eexpr
essedi
n‘
seconds’(
t
hedef
aul
tset
t
i
ngi
s
‘
mi
nut
esandseconds’
)
.Fr
om t
he‘
Vi
ew’
menu,got
o
‘
SetSel
ect
i
onFor
mat
’
andchoose‘
sec’
.
To look at the signals in more detail and to look at
the time intervals, it is possible to expand the time
axis using the zoom in tool.
The following diagrams shows the steps involved:
Select the region to
expandby‘
cl
i
cki
ngand
dr
aggi
ng’
.
Repeat
edl
ycl
i
ckont
he‘
Zoom i
n’
t
ool
until the desired magnification is
achieved.
Select the time interval to
measur
eby‘
cl
i
cki
ngand
dr
aggi
ng’
.
The time interval is displayed on the bottom of the
Audacity window –in this case it is about 0.0067
seconds (i.e. 6.7 milliseconds).
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INNOVATIONS IN PRACTICAL W ORK: SEISMOLOGY
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TROUBLESHOOTING
If you do not get any signal displayed, or you get a poor signal then there are a number of steps you
can take.
1. Check the volume setting of the microphone on
y
ourcomput
er
’
sVol
umeCont
r
olPanel
.Youcan
opent
hi
spanelbygoi
ngt
ot
hecomput
er
’
sCont
r
ol
Panel
,andt
hensel
ect
i
ng‘
SoundandAudi
o
Devi
ces’
.
2. Check that the selected input on the Audacity
sof
t
war
ei
s‘
Mi
cr
ophone’
–this is displayed in the
Audacity toolbar. This can be changed using the
drop down menu.
3. If you are using a laptop (which has an internal
microphone), then you need to make sure that the
external microphone socket is selected. Go to your
comput
er
’
sVol
umeCont
r
olPanel
,andcl
i
ckont
he
‘
Adv
anced’
but
t
onunder
neat
ht
hemi
cr
ophone
v
ol
umecont
r
ol
(
seenot
e1abov
e)
.The‘
Adv
anced
Cont
r
ol
sf
orMi
cr
ophone’
shoul
dbedi
spl
ay
ed.The
checkbox‘
Fr
ontPanel
Mi
cr
ophone’shoul
dbe blank
–if it is ticked, then click it to deselect.
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INNOVATIONS IN PRACTICAL W ORK: SEISMOLOGY
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4. If your signal is distorted with a lot of noise, then
check that the microphone boost is switched off: go
t
ot
he‘
Adv
ancedCont
r
ol
sf
orMi
cr
ophone’panel
(
seenot
e3)
.Thecheckbox‘
MI
Cboost
’
shoul
dbe
blank.
5. Depending on the default setting, you may need to
changet
he‘
Recor
di
ngDevi
ce’
sel
ect
edi
nAudaci
t
y
.
Fr
om t
he‘
Edi
t
’
menui
nAudaci
t
y
,sel
ect
‘
Pr
ef
er
ences’
;ont
heAudi
oI
/
Ot
ab,uset
hedr
op
down menu to change the recording device if
necessary.
FURTHER INFORMATION
The seismology practical kits and copies of the SEP publication Seismology and can be purchased from Middlesex University
Teaching Resources (www.mutr.co.uk).
Visit the SEP website (www.sep.org.uk) for information on how to become an SEP Associate and how to obtain further
curriculum resources.
Gatsby Science Enhancement Programme
Institute of Education, University of London
Room 202, 11 Woburn Square
London WC1H 0AL
Email: [email protected]
Web: www.sep.org.uk
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