Voice Quality + Spectral Analysis

Voice Quality + Spectral Analysis

Feburary 13, 2013

Today1. Today:

• Wrap up voice quality discussion

• Begin examination of spectral analysis

2. On the Monday after the break: back in the computer lab (CHD 428).

• Analysis of Korean stops.

3. Remember:

• mid-term on Friday

• In EDC 384

• Take home portion will be passed out at the end of class today.

4. Whispery Voice• When we whisper:

• The cartilaginous glottis remains open, but the ligamental glottis is closed.

• Air flow through opening with a “hiss”

• The laryngeal settings:

1. Little or no adductive tension

2. Moderate to high medial compression

3. Moderate airflow

4. Longitudinal tension is irrelevant…

• Check out another video.

Nodules• One of the more common voice disorders is the development of nodules on either or both of the vocal folds.

• nodule = callous-like bump

• What effect might this have on voice quality?

Last but not least• What’s going on here?

• At some point, my voice changes from modal to falsetto.

5. Falsetto• The laryngeal specifications for falsetto:

1. High longitudinal tension

2. High adductive tension

3. High medial compression

• Contraction of thyroarytenoids

4. Lower airflow than in modal voicing

• The results:

• Very high F0.

• Very thin area of contact between vocal folds.

• Air often escapes through the vocal folds.

Falsetto EGG

• The falsetto voice waveform is considerably more sinusoidal than modal voice.

Some Real EGGs

Modal voice (F0 = 140 Hz)

Falsetto voice (F0 = 372 Hz)

Voice Quality SummaryAT LT MC Flow

Modal moderate varies moderate med.

Tense high varies high high

Creaky high low high low

Whisper low N/A high med.

Breathy low varies low high

Falsetto high high high low

• Last but not least, Korean makes an interesting distinction between “emphatic” (or fortis) obstruents and unaspirated and aspirated (lenis) obstruents.

What’s going on here?• A variety of things occur during the articulation of fortis

consonants in Korean.

1. Glottis is not open as wide (during closure) as in lenis stops.

Voicing begins more quickly after stop release

2. Increased airflow in fortis stops.

Higher F0 after stop release.

3. Vocal folds are “more tense” than in lenis stops.

• = greater medial compression

• = “squarer” glottal waveform

Back to the Source…• Modal voicing (by me):

• Note: completely closed and completely open phases are both actually quite short.

• Also: closure slope is greater than opening slope.

• Q: Why might there be differences in slope?

A Different Kind of Voicing• The basic voice quality in khoomei is called xorekteer.

• Notice any differences in the EGG waveforms?

• This voice quality requires greater medial compression of the vocal folds.

• ...and also greater airflow

Why Should You Care?• Remember that the most basic kind of sound wave is a sinewave.

time

pressure

• Sinewaves can be defined by three basic properties:

• Frequency, (peak) amplitude, phase

Complex Waves• It is possible to combine more than one sinewave together into a complex wave.

• At any given time, each wave will have some amplitude value.

• A1(t1) := Amplitude value of sinewave 1 at time 1

• A2(t1) := Amplitude value of sinewave 2 at time 1

• The amplitude value of the complex wave is the sum of these values.

• Ac(t1) = A1 (t1) + A2 (t1)

• Note: a harmonic is simply a component sinewave of a complex wave.

Complex Wave Example• Take waveform 1:

• high amplitude

• low frequency

• Add waveform 2:

• low amplitude

• high frequency

• The sum is this complex waveform:

+

=

Another Perspective• Sinewaves can also be represented by their power spectra.

• Frequency on the x-axis

• Intensity on the y-axis (related to peak amplitude)

Waveform Power Spectrum

Putting the two togetherWaveform Power Spectrum

+ +

= =

harmonics

More Combinations

• What happens if we keep adding more and more high frequency components to the sum?

+ =

+ =

A Spectral ComparisonWaveform Power Spectrum

What’s the Point?• Remember our EGG waveforms for the different

kinds of voice qualities:

• The glottal waveform for tense voice resembles a square wave.

• lots of high frequency components (harmonics)

What’s the point, part 2• A modal voicing EGG looks like:

• It is less square and therefore has less high frequency components.

• Although it is far from sinusoidal...

What’s the point, part 3• Breathy and falsetto voice are more sinusoidal...

• And therefore the high frequency harmonics have less power, compared to the fundamental frequency.

Let’s Check ‘em out• Head over to Praat and check out the power spectra of:

• a sinewave

• a square wave

• a sawtooth wave

• tense voice

• modal voice

• creaky voice

• breathy voice

Spectral Tilt

• Spectral tilt = drop-off in intensity of higher harmonics, compared to the intensity of the fundamental.

The Source• The complex wave emitted from the glottis during voicing=

• The source of all voiced speech sounds.

• In speech (particularly in vowels), humans can shape this spectrum to make distinctive sounds.

• Some harmonics may be emphasized...

• Others may be diminished (damped)

• Different spectral shapes may be formed by particular articulatory configurations.

• ...but the process of spectral shaping requires the raw stuff of the source to work with.