Nasality methodology

Nasality methodology

Oral-nasal airflow: experimental methodology

Participants

In order to control for the effects of language or dialect background on the results of the experiment only people who are native speakers of Australian English are recorded. This is because there may be language or dialect specific difference in velum opening patterns that might affect the results.

Method and materials

Each experimental participant first has the oral-nasal separator mask placed on their face. Care must be taken in getting an air-tight seal between the mask and each participant's face.  Some faces do not fit the mask. We have only one mask size but there are many different face shapes and sizes. See the workshop video for details of this procedure and the related calibration methodology.

Speech materials

Each subject is asked to read four nonsense sentences, the list of words (in a carrier phrase), and finally the phonetically balanced "Rainbow" passage and a second phonetically unbalanced "Naomi" passage. The subject must read in a FIRM voice which should not be breathy and which should be loud rather than soft and slow rather than fast.

The four nonsense sentences are:-

SentenceVowel
Yee beez feed treez /i:/
You booze food trooz. /u:/
Your borz ford trawz. /o:/
Yar barz fard trarz. /a:/

You will note that each of these sentences is characterised by having only one vowel, repeated four times in various consonantal contexts.

The four words are (in the context "CHOP /_a_/"):-
/ba:b/
/ma:/
/a:m/
/ma:m/

In these words the same vowel /a:/ can be found in various oral and nasal stop contexts. As velum closure is required for oral stops and velum opening is required for nasal stops then these words permit us to examine the effects of preceding and following consonants on oral-nasal airflow and sound pressure patterns during the vowel.

"Rainbow" and "Naomi" passage statistics

The "Rainbow passage" is a "phonetically balanced" passage where the ratios of the various phonemes reflect the ratios of those phonemes in normal unscripted speech. You should note that a more correct description of such a passage would be "phonemically balanced". The Naomi passage is remarkable in its very heavy concentration of nasal consonants. The two passages are compared in the following table.

Rainbow passage (phonetically balanced)
Total phonemes 317   Total syllables 125
Total nasal phonemes 33   Total nasal syllables 32
% nasal phonemes 10%   % nasal syllables 26%
 
Naomi passage (unbalanced for nasals)
Total phonemes 153   Total syllables 59
Total nasal phonemes 36   Total nasal syllables 31
% nasal phonemes 24%   % nasal syllables 53%

THE RAINBOW PASSAGE (phonetically balanced)

WHEN SUNLIGHT STRIKES RAINDROPS IN THE AIR THEY ACT LIKE A PRISM AND FORM A RAINBOW.

THE RAINBOW IS A DIVISION OF WHITE LIGHT INTO MANY BEAUTIFUL COLOURS.

THESE TAKE THE SHAPE OF A LONG ROUND ARCH WITH ITS PATH HIGH ABOVE, AND ITS ENDS APPARENTLY BEYOND THE HORIZON.

THERE IS, ACCORDING TO LEGEND, A BOILING POT OF GOLD AT ONE END.

PEOPLE LOOK BUT NO ONE EVER FINDS IT.

WHEN A MAN LOOKS FOR SOMETHING BEYOND HIS REACH, HIS FRIENDS SAY HE IS LOOKING FOR THE POT OF GOLD AT THE END OF THE RAINBOW. (Fairbanks, G. (1960), Voice and Articulation Drillbook, New York: Harper & Row, pp. 124-139)

THE "NAOMI" PASSAGE (phonetically unbalanced)

NAOMI REMEMBERED THAT JUNE NIGHT WHEN THE MOON SHONE ON THE MOOR AS SHE WANDERED AIMLESSLY TOWARD THE RUINED MANSION.

FRAMED BETWEEN A BACKDROP OF ELMS THE MOON GLINTED ON THE MONEY THAT THE MAD MANNERING WAS FINGERING AND COUNTING.

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