Frequency, Pitch, Tone and Length October 16, 2013 Thanks to Chilin Shih for making some of these lecture materials available.

Announcements For Friday: transcription exercise on tone. Yoruba and a mystery tone language! Production exercise #2 due at 5 pm next Monday (the 21st). Okay, let’s go back to looking at sound waves…

Compression Wave A wave of force travels down the line of molecules Ultimately: individual molecules vibrate back and forth, around an equilibrium point The transfer of force sets up what is called a compression wave. What gets “compressed” is the space between molecules

Compression Wave area of high pressure (compression) area of low pressure (rarefaction) Compression waves consist of alternating areas of high and low pressure

Pressure Level Meters Microphones Have diaphragms, which move back and forth with air pressure variations Pressure variations are converted into electrical voltage Ears Eardrums move back and forth with pressure variations Amplified by components of middle ear Eventually converted into neurochemical signals We experience fluctuations in air pressure as sound

Measuring Sound What if we set up a pressure level meter at one point in the wave? Time pressure level meter How would pressure change over time?

Sine Waves The reading on the pressure level meter will fluctuate between high and low pressure values In the simplest case, the variations in pressure level will look like a sine wave. time pressure

Other Basic Sinewave concepts Sinewaves are periodic; i.e., they recur over time. The period is the amount of time it takes for the pattern to repeat itself. The frequency is the number of times, within a given timeframe, that the pattern repeats itself. Frequency = 1 / period usually measured in cycles per second, or Hertz The peak amplitude is the the maximum amount of vertical displacement in the wave = maximum/minimum amount of pressure

Complex Waves When more than one sinewave gets combined, they form a complex wave. At any given time, each wave will have some amplitude value. A 1 (t 1 ) := Amplitude value of sinewave 1 at time 1 A 2 (t 1 ) := Amplitude value of sinewave 2 at time 1 The amplitude value of the complex wave is the sum of these values. A c (t 1 ) = A 1 (t 1 ) + A 2 (t 1 )

Complex Wave Example Take waveform 1: high amplitude low frequency Add waveform 2: low amplitude high frequency The sum is this complex waveform: + =

Other Examples 480 Hz tone 620 Hz tone the combo = ?

Fundamental Frequency The fundamental frequency of a complex wave is the frequency at which the complex wave repeats itself. = greatest common denominator of frequencies of component waves. Greatest common denominator = largest number that two (or more) numbers can be divided by to yield an integer (whole number) value. Q: What’s the fundamental frequency of a complex wave consisting of 600 Hz and 800 Hz tones? How about one with 120 Hz and 150 Hz tones?

Linguistically Speaking In speech, the fundamental frequency of voiced sounds is based on the rate at which the vocal folds open and close. The wave set up by the vocal folds is a complex wave.

Complex Wave Visual Combination of 100 Hz and 300 Hz wave. Voicing sort of looks like this, but it’s even more complex:

Why Should You Care? The modulation of fundamental frequency in speech can have linguistic meaning. Tone Pitch Accent Stress Intonation Since this modulation can occur (relatively) independently of the stream of vowel and consonant segments in speech… these linguistic properties are often referred to as suprasegmentals.

Suprasegmentals Suprasegmentals are phonetic features of speech which are “above the segment” Tone/Accent/Intonation Quantity Stress “Suprasegmental features are established by a comparison of items in a sequence.” --Ilse Lehiste (1970)  Suprasegmental features are always defined in a relative manner.

Where Tone Comes From Here’s a waveform for my vowel : The acoustic shockwave of each opening of the vocal folds shows up as a vertical bar in the waveform. A “voicing bar”

Voicing Bar Close-up Individual glottal pulses

Voicing bars, really close up The fundamental frequency of voicing can be calculated by measuring the period between glottal pulses. Voicing is a complex wave. (i.e., not sinusoidal)

Voicing bars, really close up Frequency = 1 / period In this case, period =.008 seconds, so frequency = ? period

Pitch Tracks Measuring the fundamental frequency (F0) at every step in a sound file yields a pitch track. Time on the x-axis. Fundamental frequency on the y-axis. F0 time I’d like to collect sea shells this after noon

Just So You Know Praat has an automatic pitch tracker. Check it out. It can be messed up by: voiceless sounds obstruents (stops, fricatives, affricates) Also, it can sometimes double or halve the correct fundamental frequency. I’ll spare you the technical reasons why. In general, though, it works well.

Tone Tone is the linguistic use of fundamental frequency to signal important differences in meaning. Note: Acoustic=Fundamental Frequency Perceptual=Pitch Linguistic=Tone English is a tone language… Sort of. For one set of words only.

A Typology F0 generally varies in three different ways in language: 1. Tone languages (Chinese, Navajo, Igbo) Lexically determined tone on every syllable or word 2. Accentual languages (Japanese, Swedish) The location of an accent in a particular word is lexically marked. 3. Stress languages (English, Russian) It’s complicated.

Mandarin Tone ma1: mother ma2: hemp ma3: horse ma4: to scold Mandarin (Chinese) is a classic example of a tone language.

Mandarin Sentences ma1-ma0 ma4 ma3. “Mother scolds the horse.” ma3 ma4 ma1-ma0. “The horse scolds mother.”

How to Transcribe Tone Tones are defined by the pattern they make through a speaker’s frequency range. The frequency range is usually assumed to encompass five levels (1-5). (although this can vary, depending on the language) Highest F0 Lowest F0

In Mandarin, tones span a frequency range of 1-5 Each tone is denoted by its (numerical) path through the frequency range Each syllable can also be labeled with a tone number (e.g., ma1, ma2, ma3, ma4) Tone

How to Transcribe Tone Tone is relative i.e., not absolute Each speaker has a unique frequency range. For example: Highest F0 Lowest F0 FemaleMale ~100 Hz ~200 Hz~350 Hz ~150 Hz

Relativity, in Reality The same tones may be denoted by completely different frequencies, depending on the speaker.  Tone is an abstract linguistic unit. female speaker male speaker ma, tone 1 (55)

How To Transcribe Tone female speaker male speaker ma, tone 4 (51) Some speakers also use more of their frequency range.

Even More Tones level tones contour tones

Variations Other tone languages only have two or three tone targets These are transcribed as sequences of High (H) and Low (L) tones. (or also Mid (M) tones) They can also be labeled with accents over vowels High = ´ Low = ` In these languages, tone can be used for grammatical markers (tense, possession)

Ibibio Tones Ibibio is spoken in southern Nigeria