Chapter 4 The Sounds of Vowels
Acoustic Structure of Vowels
The Acoustic Vowel Space
Outlines and Summary
Each vowel will be the same note because the rate of repetition of the sound wave as a whole-fundamental frequency- is the same. The quality will be different because the smaller variations within each repetition of the sound wave-the overtones- will be different.
The acoustic vowel space can be considered to be an area bounded by the possible ranges for the frequencies of the first two formants. The three vowels I, a, u, are as auditorily distinct as possible, they are very effective ways of distinguishing words, and many languages make use of them. If a language uses a still larger number of vowels, then they may be distinguished not only by differences in their formant frequencies but also by other differences such as length.
3. The explanation of terminologies by Crystal’s (2000) definition.
Harmonic. In acoustic phonetics, a regular (periodic) waveform accompanying a fundamental frequency, which helps to identify a complex tone; also called an overtone. Harmonics are whole-number multiples of the fundamental frequency; for example, if the fundamental is 200 Hz, the harmonics will be at 400 Hz, 600 Hz, and so on. The harmonics are numbered in sequence, and in phonetics the numbering stats with the first multiple of the fundamental (in this example, 400 Hz would be the “first harmonic”, 600 Hz the “second harmonic”, and so on). The combination of a fundamental frequency and the amplitude of its various harmonics combine to give a sound its characteristic tone and quality.
Formant. A term in acoustic phonetics of particular value in the classification of the vowels and vowel-like sounds, and of transitional features between vowels and adjacent sounds. A formant is a concentraction of acoustic energy, reflecting the way air from the lungs vibrates in the vocal tract, as it changes its shape. For any vowel, the air vibrates at many different frequencies all at once, and the most dominant frequencies combine to produce the distinctive vowel qualities. Each dominant band of frequencies constitutes a formant, which shows up clearly in a record produced by a sound spectrograph as a thick black line. Three main formants provide the basis of vowel description: the ”first formant” is the lowest, and the “second” and “third formants” are respectively higher. Other formants are less significant for linguistic analysis. The formants can be related to the articulartory description of vowels, as represented, say, by the cardinal vowel diagram. The first formant, for example, decreases in its frequency as one moves from low to high (e.g. sat à set à seat). In the case of consonants, similar correlations can be established: for example, in the transition from velar consonants, the second and third formants come very close together.
Spectrograph (Spectrogram). An instrument used in acoustic phonetics which provides a visual representation of the acoustic features that constitute the sounds in an utterance. The original “sound spectrograph” produced by a three dimensional visual record, or “spectrogram”, of an utterance, in which time is diplayed horizontally, frequency vertically, and intensity by the relative blackness of the marks, on a sheet of sensitized paper. Today, spectrographic information can be generated electronically and displayed on a screen.
4. The translation of key words in English-Chinese version.
Fundamental frequency 基礎頻率
Sound spectrograph 聲譜圖
D. (2000). A dictionary of Linguistics and Phonetics. (4th ed.).
MA: Blackwell Publishers Inc.