Plosive Sounds Research Articles

Computer recognition of plosive sounds using contextual information

The design of the plosive consonant recognition component of a speech understanding system is described. The recognition rules used incorporate information on coarticulatory and multiple cue effects. The rule combination and scoring system is a fuzzy model of the human speech perception and information integration mechanism. These rules can be also used in classical stochastic models or dynamic programming approaches to automatic speech recognition.

Phonetics curriculum development and implementation for the deaf university student.

Phonetics Curriculum Development and Implementation for the Deaf University Student Darlene Geer Gould Deaf university students are among the undergraduate and graduate students in communication disorders programs. The deaf students train to clinically and educationally work with communicatively impaired individuals, particularly hearing-impaired persons. The population to be worked with by the deaf students may be comprised of infant, preschool, elementary, secondary, college, mature adult, or elder segments of society. In addition, the deaf communication disorders students may aspire to clinical research positions as career goals. A thorough understanding of theoretical constructs underlying the subject of phonetics and possession of, or at least considerable familiarity with, phonetic transcription skills is essential to the deaf communication disorders specialist. This paper addresses phonetics curriculum development and implementation concerns in conjunction with educational instruction of deaf university students. Five areas of curriculum design and the implementation necessary for learning phonetics as a deaf university student are outlined and discussed. 1. Programmed workbook materials which are organized to incrementally increased levels of difficulty must be available to each deaf student. Keys to workbook exercises should be contained within the workbooks or accompany the workbooks so that students can check their own work. Such curriculum provisions will allow students to be self-paced in the course. Carefully designed graded practice materials are particularly important to deaf students because such students cannot avail themselves of opportunities, indeed required experiences, to listen to phonetics audio tapes which are traditional modes of learning for phonetics transcription training involving sound identification. The deaf enrollee in a phonetics class will need to work from the printed page to supplied transcription sheets. A great variety of activities can be designed to introduce International Phonetic Alphabet (IPA) symbols and to encourage abundant practice in IPA tranThe author is the Clinic Coordinator, Department of Communicative Disorders at San Diego State University. scription. Not only will variety allow for graded levels of difficulty, but it will ensure maintenance of student interest. Types of workbook assignments might encompass a wide range of tasks, a few of which are suggested here. How many sounds in the words? Find words with high front vowels; Find words with low front vowels; Find words with mid front vowels; Find words with high back vowels; Find words with low back vowels; Find words with mid back vowels; Find words with central vowels; Find words with fricative sounds; Find words with plosive sounds; Find words with affricate sounds; Find words with nasal sounds; Write orthographically represented words from IPA; Find the errors; Write in IPA from orthographies; IPA sentences; IPA paragraphs; and IPA crossword puzzles. It is obvious that the deaf student cannot be expected to transcribe conversational speech. Although he/she needs to learn about regional dialects and foreign accents, theoretical knowledge will be derived regarding the nature of speech production variations rather than from direct listening experiences. 2. Technological instrumentation providing visual speech displays and tactile speech feedback is directly instructive to the deaf phonetics students. Visual and tactile modalities offer identification and verification information about human speech. Distinctive feature information can be illustrated via sonograms, speech oscilographs , video-tape, tactile phonation instruments , articulation film, cineflourographic studies , visual vocal pitch display instruments, speech analyzers of various kinds, sound level meters, oral manometers, etc. Speech sound transition information derived from spectographic analysis will impart information about rapid sequencing of articulatory movements which will be A.A.D. /August 1982 447 Phonetics Curriculum Development learned to the greatest extent through the auditory modality by the hearing student. 3. It is particularly important for a comprehensive clinical phonetics textbook to be an integral part of the course. The deaf student will probably more completely rely upon the text for scholarly input than will hearing students in the same class, even though deaf students may glean information from class lectures via speech reading , sign from an interpreter, or an official note taker. Supplementarily, rather thorough bibliographic resource materials must be accessible to the deaf student. 4. Multi-media materials such as illustrated phonovisual charts which show tongue, lip, jaw, velar, and laryngeal action for sound production will be referred to time and time again by the deaf student. Drawings, molds, simulated articulatory structures...

A variable frame rate LPC vocoder using normalized ladder-forms

We present a variable frame rate LPC (Linear Predictive Coding) vocoder based on a normalized exact-least squares ladder-form analysis algorithm by Lee and Morf. This algorithm works on a sample by sample basis, hence no a priori frame rate has to be preselected. As a byproduct of this algorithm a log-likelihood variable is computed that can be used to detect discontinuities in the speech signal such as plosive sounds, pitch pulses, glottal stops and other underlying transitions. Based on this algorithm a complete design of a vocoder is presented, that allows variable frame rates, pitch synchronous speech analysis/synthesis. Such vocoders are of interest in digital communication systems, especially packet oriented systems, or digitally stored speech based systems. Computer simulations of this vocoder using a digitized speech data base are presented, and several alternative implementations are discussed.

Speech development and maxillary growth in relation to technique and timing of palatoplasty

Summary The dependability of speech development and maxillary growth on the technique and timing of palatoplasty has been re-evaluated on the basis of surgical closure of 2,022 cases of primary cleft palate operated in the Westdeutsche Kieferklinik from 1943–1971. The data gained on 1,033 patients (51.1%) were electronically analysed. The results could be summarised as follows: 1. The later result of plosive sounds is dependent on the operative procedure chosen under consideration of the morphological initial condition. 2. A direct linear relationship is existent between age at operation and speech result. 3. The measure of iatrogenic disturbance in maxillary growth depends on the technique applied in palatoplasty. 4. Without any vital damage to maxillary growth, a relatively early, but “atraumatic” palatoplasty at the age of 2–3 years can be achieved. In concluding, suggestions for surgical closure of various forms of cleft have been offered.

Studies on the Air Pressure in the Vocal Tract during Phonation

The intra-nasal, intra-oral and subglottic air pressures were measured during production of various Japanese speech sounds, andd these values of pressure were compared with the sonagrams of each sound in degree as well as in time relation.A new electromanometer, in which the mechanical pressure is changed to the electrical energy with strain guage, was used in order to record delicate changes of the pressure corresponding to each component of speech sounds.Both speech sound and air pressure were traced on the electrical oscillograph and simultaneously the former recorded with a tape-recorder to be analysed on the sonagram.The results obtained are as follows.[I] On the intra-nasal air pressure1. The intra-nasal air pressure does not rise so markedly except during production of nasal syllables. The pressure begins to rise ca. 35-50msec. prior to the phonation and reaches its maximum value 7-13mm H2O at the end of the nasal consonant and then it drops rapidly at the following vowel.2. During phonation of some vowels such as “i” or “u”, a slight rise of the intranasal air pressure is occasionally observed.[II] On the intra-oral air pressure1. The intra-oral air pressure is not observed to rise during phonation vowels or nasal syllables.2. The intra-oral air pressure begins to rise almost simultaneously with the utterance of voiced consonant syllables, i. e. with its proceeding wave. The maximum value (5-7mm H2O) of the pressure is observed at the end of the voiced consonant wave in the fricative sounds and at the beginning in the plosive sounds.3. The intra-oral air pressure begins to rise 60-80msec. prior to the phonation of the voiceless fricative consonant syllables and 170-210msec. prior to the plosives. The maximum value (7-9mm H2O) of the pressure is observed at the point of 1/4 or 1/5 of the consonant wave in the fricative sounds and at the end in the plosive sounds.4. The pressure drops rapidly at the following vowels in the both voiceless and voiced consonant syllables.[III] On the subglottic air pressure1. The subglottic air pressure rises during phonation of all speech sounds, and its maximum value is almost the same, showing the height of 30-50mm H2O.2. The subglottic air pressure begins to rise prior to the production of every speech sound. This phenomenons considered to show the “Kaiser's Effect”, and the latent period between onset of subglottic pressure and voice production varies according to speech sounds, i. e. it shows 170-190msec. in voiced vowels, 80-90msec. in nasals, 90-110msec. in voiced fricatives, 80-120 msec. in voiced plosives, 80-100msec. in voiceless fricatives and 160-190 msec.in voiceless plosive, sounds.3. There is also a difference in the way of elevation of the subglottic air pressure among speech sounds. During phonation of vowels and voiced plosive consonant syllables, the curve of ascending subglottic pressure to be traced on oscillograph is more convex, on the contrary, is more concave in nasals and voiced fricative consonants. During phonation of voiceless consonant syllables the subglottic air pressure continues to rise to the production of following vowels, but in the course a transient slight drop is always observed. This drop of air pressure corresponds to production of the transitional part of consonant syllables and follows to the time when the intra-oral air pressure shows its maximum value.