The minimal pairs included in the test
battery are chosen on the basis of knowledge of speech perception development
as some speech contrasts are acquired earlier than others. By testing
listeners on word pairs graded in terms of speech pattern complexity, it
is possible to assess the stage of speech perceptual development achieved,
which is particularly useful when testing children.
First, make recordings of a speaker saying the words and then choose one
clear example of each.
Click on the
word to listen to the words date
and gate
spoken by a female speaker.
Make a fully synthetic copy of these words using the Klatt speech synthesiser.
Click on the
word to listen to the words date
and gate
produced by the Klatt synthesiser.
Decide which speech patterns you need to vary to change the perception
of the initial consonant from /d/ to /g/. Research has shown that the initial
burst frequency and second formant transitions into the vowel are important
acoustic cues to the difference between these two consonants.
Produce a 'stimulus continuum' by changing these patterns in equal steps
between the values appropriate for /d/ and /g/. You can have as many steps
as you want, but we tend to use a six-step continuum.
Click on the step number to listen to individual steps along the /d/ to /g/ continuum. Both the burst frequency and formant transition cues are being varied:
Produce a stimulus continuum in which all acoustic cues are varying (in
this case, both the burst and formant transition, as shown above).
Produce
a continuum in which only one cue is varying (e.g. burst). You can do this
by keeping the other cue (e.g. formant transition) constant at an intermediate
value. If a listener does the test well when both burst and formant transition
are varying but cannot hear the constrast when only the formant transition
is varying, this will suggest that the burst is the main acoustic cue for
that listener in this test.
Click on the step number to listen to individual steps along the /d/ to /g/ continuum: Only the burst is being varied in this set:
step 1 step 2 step 3 step 4 step 5 step 6
Click on the step number to listen to individual steps along the /d/ to /g/ continuum: Only the formant transition is being varied in this set:
step 1 step 2 step 3 step 4 step 5 step 6
