Acoustic phonetics
Encyclopedia
Acoustic phonetics is a subfield of phonetics
which deals with acoustic
aspects of speech
sounds. Acoustic phonetics investigates properties like the mean squared amplitude
of a waveform
, its duration, its fundamental frequency
, or other properties of its frequency spectrum
, and the relationship of these properties to other branches of phonetics (e.g. articulatory
or auditory phonetics
), and to abstract linguistic concepts like phones, phrases, or utterances.
The study of acoustic phonetics was greatly enhanced in the late 19th century by the invention of the Edison
phonograph
. The phonograph allowed the speech signal to be recorded and then later processed and analyzed. By replaying the same speech signal from the phonograph several times, filtering it each time with a different band-pass filter
, a spectrogram
of the speech utterance could be built up. A series of papers by Ludimar Hermann
published in Pflügers Archiv in the last two decades of the 19th century investigated the spectral properties of vowels and consonants using the Edison phonograph, and it was in these papers that the term formant
was first introduced. Hermann also played back vowel recordings made with the Edison phonograph at different speeds to distinguish between Willis' and Wheatstone's theories of vowel production.
Further advances in acoustic phonetics were made possible by the development of the telephone
industry. (Incidentally, Alexander Graham Bell
's father, Alexander Melville Bell
, was a phonetician.) During World War II
, work at the Bell Telephone Laboratories
(which invented the spectrograph
) greatly facilitated the systematic study of the spectral properties of periodic
and aperiodic speech sounds, vocal tract resonance
s and vowel formant
s, voice quality, prosody
, etc.
On a theoretical level, acoustic phonetics really took off when it became clear that speech acoustic could be modeled in a way analogous to electrical circuits. Lord Rayleigh
was among the first to recognize that the new electric theory could be used in acoustics, but it was not until 1941 that the circuit model was effectively used, in a book by Chiba and Kajiyama called "The Vowel: Its Nature and Structure". (Interestingly, this book by Japanese authors working in Japan was published in English at the height of World War II.) In 1952, Roman Jakobson
, Gunnar Fant
, and Morris Halle
wrote "Preliminaries to Speech Analysis", a seminal work tying acoustic phonetics and phonological theory together. This little book was followed in 1960 by Fant "Acoustic Theory of Speech Production", which has remained the major theoretical foundation for speech acoustic research in both the academy and industry. (Fant was himself very involved in the telephone industry.) Other important framers of the field include Kenneth N. Stevens
, Osamu Fujimura
, and Peter Ladefoged
.
Phonetics
Phonetics is a branch of linguistics that comprises the study of the sounds of human speech, or—in the case of sign languages—the equivalent aspects of sign. It is concerned with the physical properties of speech sounds or signs : their physiological production, acoustic properties, auditory...
which deals with acoustic
Acoustics
Acoustics is the interdisciplinary science that deals with the study of all mechanical waves in gases, liquids, and solids including vibration, sound, ultrasound and infrasound. A scientist who works in the field of acoustics is an acoustician while someone working in the field of acoustics...
aspects of speech
Manner of articulation
In linguistics, manner of articulation describes how the tongue, lips, jaw, and other speech organs are involved in making a sound. Often the concept is only used for the production of consonants, even though the movement of the articulars will also greatly alter the resonant properties of the...
sounds. Acoustic phonetics investigates properties like the mean squared amplitude
Amplitude
Amplitude is the magnitude of change in the oscillating variable with each oscillation within an oscillating system. For example, sound waves in air are oscillations in atmospheric pressure and their amplitudes are proportional to the change in pressure during one oscillation...
of a waveform
Waveform
Waveform means the shape and form of a signal such as a wave moving in a physical medium or an abstract representation.In many cases the medium in which the wave is being propagated does not permit a direct visual image of the form. In these cases, the term 'waveform' refers to the shape of a graph...
, its duration, its fundamental frequency
Fundamental frequency
The fundamental frequency, often referred to simply as the fundamental and abbreviated f0, is defined as the lowest frequency of a periodic waveform. In terms of a superposition of sinusoids The fundamental frequency, often referred to simply as the fundamental and abbreviated f0, is defined as the...
, or other properties of its frequency spectrum
Frequency spectrum
The frequency spectrum of a time-domain signal is a representation of that signal in the frequency domain. The frequency spectrum can be generated via a Fourier transform of the signal, and the resulting values are usually presented as amplitude and phase, both plotted versus frequency.Any signal...
, and the relationship of these properties to other branches of phonetics (e.g. articulatory
Articulatory phonetics
The field of articulatory phonetics is a subfield of phonetics. In studying articulation, phoneticians explain how humans produce speech sounds via the interaction of different physiological structures....
or auditory phonetics
Auditory phonetics
Auditory phonetics is a branch of phonetics concerned with the hearing of speech sounds and with speech perception.-See also:* Acoustic phonetics* Auditory illusion* Auditory processing disorder* Hearing * Motor theory of speech perception...
), and to abstract linguistic concepts like phones, phrases, or utterances.
The study of acoustic phonetics was greatly enhanced in the late 19th century by the invention of the Edison
Thomas Edison
Thomas Alva Edison was an American inventor and businessman. He developed many devices that greatly influenced life around the world, including the phonograph, the motion picture camera, and a long-lasting, practical electric light bulb. In addition, he created the world’s first industrial...
phonograph
Phonograph
The phonograph record player, or gramophone is a device introduced in 1877 that has had continued common use for reproducing sound recordings, although when first developed, the phonograph was used to both record and reproduce sounds...
. The phonograph allowed the speech signal to be recorded and then later processed and analyzed. By replaying the same speech signal from the phonograph several times, filtering it each time with a different band-pass filter
Band-pass filter
A band-pass filter is a device that passes frequencies within a certain range and rejects frequencies outside that range.Optical band-pass filters are of common usage....
, a spectrogram
Spectrogram
A spectrogram is a time-varying spectral representation that shows how the spectral density of a signal varies with time. Also known as spectral waterfalls, sonograms, voiceprints, or voicegrams, spectrograms are used to identify phonetic sounds, to analyse the cries of animals; they were also...
of the speech utterance could be built up. A series of papers by Ludimar Hermann
Ludimar Hermann
Ludimar Hermann was a German physiologist and speech scientist who used the Edison phonograph to test theories of vowel production, particularly those of Robert Willis and Charles Wheatstone. He coined the word formant, a term of importance in modern acoustic phonetics...
published in Pflügers Archiv in the last two decades of the 19th century investigated the spectral properties of vowels and consonants using the Edison phonograph, and it was in these papers that the term formant
Formant
Formants are defined by Gunnar Fant as 'the spectral peaks of the sound spectrum |P|' of the voice. In speech science and phonetics, formant is also used to mean an acoustic resonance of the human vocal tract...
was first introduced. Hermann also played back vowel recordings made with the Edison phonograph at different speeds to distinguish between Willis' and Wheatstone's theories of vowel production.
Further advances in acoustic phonetics were made possible by the development of the telephone
Telephone
The telephone , colloquially referred to as a phone, is a telecommunications device that transmits and receives sounds, usually the human voice. Telephones are a point-to-point communication system whose most basic function is to allow two people separated by large distances to talk to each other...
industry. (Incidentally, Alexander Graham Bell
Alexander Graham Bell
Alexander Graham Bell was an eminent scientist, inventor, engineer and innovator who is credited with inventing the first practical telephone....
's father, Alexander Melville Bell
Alexander Melville Bell
Alexander Melville Bell was a teacher and researcher of physiological phonetics and was the author of numerous works on orthoepy and elocution....
, was a phonetician.) During World War II
World War II
World War II, or the Second World War , was a global conflict lasting from 1939 to 1945, involving most of the world's nations—including all of the great powers—eventually forming two opposing military alliances: the Allies and the Axis...
, work at the Bell Telephone Laboratories
Bell Labs
Bell Laboratories is the research and development subsidiary of the French-owned Alcatel-Lucent and previously of the American Telephone & Telegraph Company , half-owned through its Western Electric manufacturing subsidiary.Bell Laboratories operates its...
(which invented the spectrograph
Spectrograph
A spectrograph is an instrument that separates an incoming wave into a frequency spectrum. There are several kinds of machines referred to as spectrographs, depending on the precise nature of the waves...
) greatly facilitated the systematic study of the spectral properties of periodic
Frequency
Frequency is the number of occurrences of a repeating event per unit time. It is also referred to as temporal frequency.The period is the duration of one cycle in a repeating event, so the period is the reciprocal of the frequency...
and aperiodic speech sounds, vocal tract resonance
Resonance
In physics, resonance is the tendency of a system to oscillate at a greater amplitude at some frequencies than at others. These are known as the system's resonant frequencies...
s and vowel formant
Formant
Formants are defined by Gunnar Fant as 'the spectral peaks of the sound spectrum |P|' of the voice. In speech science and phonetics, formant is also used to mean an acoustic resonance of the human vocal tract...
s, voice quality, prosody
Prosody (linguistics)
In linguistics, prosody is the rhythm, stress, and intonation of speech. Prosody may reflect various features of the speaker or the utterance: the emotional state of the speaker; the form of the utterance ; the presence of irony or sarcasm; emphasis, contrast, and focus; or other elements of...
, etc.
On a theoretical level, acoustic phonetics really took off when it became clear that speech acoustic could be modeled in a way analogous to electrical circuits. Lord Rayleigh
John Strutt, 3rd Baron Rayleigh
John William Strutt, 3rd Baron Rayleigh, OM was an English physicist who, with William Ramsay, discovered the element argon, an achievement for which he earned the Nobel Prize for Physics in 1904...
was among the first to recognize that the new electric theory could be used in acoustics, but it was not until 1941 that the circuit model was effectively used, in a book by Chiba and Kajiyama called "The Vowel: Its Nature and Structure". (Interestingly, this book by Japanese authors working in Japan was published in English at the height of World War II.) In 1952, Roman Jakobson
Roman Jakobson
Roman Osipovich Jakobson was a Russian linguist and literary theorist.As a pioneer of the structural analysis of language, which became the dominant trend of twentieth-century linguistics, Jakobson was among the most influential linguists of the century...
, Gunnar Fant
Gunnar Fant
Carl Gunnar Michael Fant was professor emeritus at the Royal Institute of Technology in Stockholm. He was a first cousin of George Fant.Gunnar Fant received a Master of Science in Electrical Engineering in 1945...
, and Morris Halle
Morris Halle
Morris Halle , is a Latvian-American Jewish linguist and an Institute Professor and professor emeritus of linguistics at the Massachusetts Institute of Technology...
wrote "Preliminaries to Speech Analysis", a seminal work tying acoustic phonetics and phonological theory together. This little book was followed in 1960 by Fant "Acoustic Theory of Speech Production", which has remained the major theoretical foundation for speech acoustic research in both the academy and industry. (Fant was himself very involved in the telephone industry.) Other important framers of the field include Kenneth N. Stevens
Kenneth N. Stevens
Kenneth N. Stevens is Clarence J. LeBel Professor of Electrical Engineering and Computer Science, and Professor of Health Sciences and Technology at MIT. Stevens heads the Speech Communication Group in MIT's Research Laboratory of Electronics , and is one of the world's leading scientists in...
, Osamu Fujimura
Osamu Fujimura
is a Japanese politician of the Democratic Party of Japan, a member of the House of Representatives in the Diet . A native of Osaka, Osaka and graduate of Hiroshima University, he was elected to the House of Representatives for the first time in 1993 as a member of the Japan New Party. He lost in...
, and Peter Ladefoged
Peter Ladefoged
Peter Nielsen Ladefoged was an English-American linguist and phonetician who traveled the world to document the distinct sounds of endangered languages and pioneered ways to collect and study data . He was active at the universities of Edinburgh, Scotland and Ibadan, Nigeria 1953–61...
.