1. †Department of Speech Music Hearing, KTH, Stockholm, Sweden
Subglottal pressure and NAQ variation
in Classically Trained Baritone Singers
Eva Björkner*†, Johan Sundberg†, Paavo Alku
*Laboratory of Acoustics and Audio Signal Processing, Helsinki University of Technology, Finland
†Department of Speech Music Hearing, KTH, Stockholm, Sweden
Hoarse meeting in Liverpool
April 22, 2005

2. Voice production
Sound => vowels and consonants
Oscillation =>pulsating air flow => voice source
Air => Subglottal pressure (Ps)

3. Flow (Rothenberg mask)
Inverse Filtering
DeCap – Svante Granqvist
TEAC Multi channel
digital recorder
Flow (Rothenberg mask)
Audio
Oral
pressure

4. Flow glottogram parameters
(Time-based & amplitude-based)
0,002
0,004
0,006
0,008
0,01
0,012
Time [s]
Time [T0]
Derivative
[MFDR]
Ûp-t-p
Peak-to-peak pulse amplitude
Flow Derivative
Flow
Time [s]

5. Glottal closing phase
Information about vocal loudness and phonation type are reflected in the changes of the glottal closing phase.
Negative peak of the differentiated flow
The first studies using parameterization of the glottal flow based on amplitude domain measurements was made by Fant & Lin in 1988.
In 1994 Fant et al. introduced the effective declination time and presented a time-domain measure by computing the ratio between two amplitude values, the AC-flow and the derivative of the differentiated flow, eg., the maximum flow declination rate MFDR

6. NAQ, the normalized AQ Ûp-t-p MFDR AQ T0
In parallel with Fant´s studies, Alku & Vilkman introduced the Amplitude Quotient AQ in studies 1996
Ûp-t-p
MFDR
Maximum flow declination rate
Alku et al. found that the AQ parameter systematically reflected changes in phonation mode and that AQ differed between sexes.
NAQ, the normalized AQ
which normalizes the AQ values with respect to the duration of the fundamental period T0. AQ T0
Alku P, Bäckström T, Vilkman E. (2002)

7. What kind of information about voice production can NAQ give?
It has so far been used in studies about :
Speech
intensity
phonation type
vocal loading
emotional expressions
voice quality
Singing
singing styles
register

8. Subglottal pressure and NAQ variation
in Classically Trained Baritone Singers
Eva Björkner*†, Johan Sundberg†, Paavo Alku
five Swedish professional baritone singers
international opera carriers
age range years

9. A sung diminuendo at a constant pitch while repeating the syllable [pae:]
Audio
Pressure
Ten equally spaced Ps-values were selected from each singers total Ps range.
Sung at three F0 located at approximately 25%, 50% and 75%
of their professional pitch range

10. Ps means for the 5 singers
Highly structured data
Fundamental frequency and pressure are strongly correlated

11. Pressure differences between octaves

12. Means across the 5 singers
MFDR increases with increasing Ps
For the same Ps the low F0 shows higher MFDR-values
=> due to the longer period time

13. NAQ => Information about phonation type NAQ differs with F0
NAQ decreases with
increasing Ps
Open symbol=high F0
Filled symbol= low F0
NAQ decreases with
increasing MFDR
NAQ differs with F0

14. Higher NAQ-values for higher F0…
Does that mean that these professional singers change phonation type with increasing F0??!!
Why these differences when we have normalized?!

15. AQ
Open symbol=high F0
Filled symbol= low F0

16. What happened?
An effect of the singers´ skill to keep the same phonation type independently of Ps and F0?
AQ should give a steady value if phonation type is kept

18. NAQ or AQ
Speaker do not have large changes in F0, but change phonation mode
Singers have large changes in F0, but do not change phonation mode => AQ…

19. ? Conclusions Does AQ more accurately reflect phonation mode than NAQ
The five singer’s Ps data were highly structured
Approximately a doubling of Ps for a doubling of F0
For the same Ps the low F0 showed higher MFDR-values
For a given Ps increase MFDR increased more at low F0
Does AQ more accurately reflect phonation mode than NAQ ?

20. The End