electroglottograph The electroglottograph, or EGG, (also referred to as a laryngograph) is a device used for the noninvasive measurement of the degree of contact between the vibrating vocal folds during voice production. Though it is difficult to verify the assum ...

ic wavegram (short: EGG wavegram) is a tool for analyzing the

voice The human voice consists of sound made by a human being using the vocal tract, including talking, singing, laughing, crying, screaming, shouting, humming or yelling. The human voice frequency is specifically a part of human sound production in ...

source in

speech Speech is a human vocal communication using language. Each language uses Phonetics, phonetic combinations of vowel and consonant sounds that form the sound of its words (that is, all English words sound different from all French words, even if ...

and

singing Singing is the act of creating musical sounds with the voice. A person who sings is called a singer, artist or vocalist (in jazz and/or popular music). Singers perform music (arias, recitatives, songs, etc.) that can be sung with or without ...

, based on electroglottographic (EGG)

signals In signal processing, a signal is a function that conveys information about a phenomenon. Any quantity that can vary over space or time can be used as a signal to share messages between observers. The ''IEEE Transactions on Signal Processing'' ...

(and their first

derivative In mathematics, the derivative of a function of a real variable measures the sensitivity to change of the function value (output value) with respect to a change in its argument (input value). Derivatives are a fundamental tool of calculus. F ...

, DEGG).

Assessing the singing and speaking voice

The wavegram, invented by Christian T. Herbst, provides an intuitive means for quickly assessing

vocal fold The human voice consists of sound made by a human being Humans (''Homo sapiens'') are the most abundant and widespread species of primate, characterized by bipedality, bipedalism and exceptional cognitive skills due to a large and compl ...

contact phenomena and their variation over time. Vocal fold closings and openings appear here as a sequence of events rather than single incidents, taking place over a certain period of time, and changing with pitch,

loudness In acoustics, loudness is the subjectivity, subjective perception of sound pressure. More formally, it is defined as, "That attribute of auditory sensation in terms of which sounds can be ordered on a scale extending from quiet to loud". The rel ...

and

register Register or registration may refer to: Arts entertainment, and media Music * Register (music), the relative "height" or range of a note, melody, part, instrument, etc. * ''Register'', a 2017 album by Travis Miller * Registration (organ), th ...

. Wavegrams document systematic phenomena, indicating subtle changes of the vocal fold

oscillatory Oscillation is the repetitive or periodic variation, typically in time, of some measure about a central value (often a point of equilibrium) or between two or more different states. Familiar examples of oscillation include a swinging pendulum ...

regime. Electroglottographic wavegrams are created in 5 steps (see illustration): # extraction of consecutive glottal cycles from the EGG signal; # locally normalized data values are converted into

monochrome A monochrome or monochromatic image, object or palette is composed of one color (or values of one color). Images using only shades of grey are called grayscale (typically digital) or black-and-white (typically analog). In physics, monochrom ...

color information, and are plotted as a strip representing one glottal cycle each; # strips are rotated 90 degrees

counter-clockwise Two-dimensional rotation can occur in two possible directions. Clockwise motion (abbreviated CW) proceeds in the same direction as a clock's hands: from the top to the right, then down and then to the left, and back up to the top. The opposite ...

; # Glottal cycle duration is normalized by

scaling Scaling may refer to: Science and technology Mathematics and physics * Scaling (geometry), a linear transformation that enlarges or diminishes objects * Scale invariance, a feature of objects or laws that do not change if scales of length, energ ...

the individual glottal cycle plots to the same height; # the resulting graphs are combined to form the final display, the EGG wavegram. Wavegram data can be influenced by # the

anatomical Anatomy () is the branch of biology concerned with the study of the structure of organisms and their parts. Anatomy is a branch of natural science that deals with the structural organization of living things. It is an old science, having it ...

baseline of the individual; #

physiological Physiology (; ) is the scientific study of functions and mechanisms in a living system. As a sub-discipline of biology, physiology focuses on how organisms, organ systems, individual organs, cells, and biomolecules carry out the chemical ...

and habitual muscular patterns in

phonation The term phonation has slightly different meanings depending on the subfield of phonetics. Among some phoneticians, ''phonation'' is the process by which the vocal folds produce certain sounds through quasi-periodic vibration. This is the defini ...

, e.g. degree of vocal fold

adduction Motion, the process of movement, is described using specific anatomical terms. Motion includes movement of organs, joints, limbs, and specific sections of the body. The terminology used describes this motion according to its direction relative ...

, register in singing and speech; # organic

voice disorders Voice disordersTitze, I.R. (1994). Principles of Voice Production, Prentice Hall, . are medical conditions involving abnormal pitch, loudness or quality of the sound produced by the larynx and thereby affecting speech production. These include: * ...

, i.e.

pathological Pathology is the study of the causal, causes and effects of disease or injury. The word ''pathology'' also refers to the study of disease in general, incorporating a wide range of biology research fields and medical practices. However, when us ...

deviations from the norm. Wavegrams show a potential to be used in: * screenings for voice disorders (e.g. in schools); * (real-time) bio-feedback in

voice pedagogy Vocal pedagogy is the study of the art and science of voice instruction. It is used in the teaching of singing and assists in defining what singing is, how singing works, and how proper singing technique is accomplished. Vocal pedagogy covers a ...

and education; *

voice therapy Voice therapy consists of techniques and procedures that target vocal parameters, such as vocal fold closure, pitch, volume, and quality. This therapy is provided by speech-language pathologists and is primarily used to aid in the management of v ...

(functional voice disorders); * conservative and post-operative treatment of organic voice disorders; * voice recognition in forensics. To construct a wavegram, the time-varying

fundamental frequency The fundamental frequency, often referred to simply as the ''fundamental'', is defined as the lowest frequency of a periodic waveform. In music, the fundamental is the musical pitch of a note that is perceived as the lowest partial present. In ...

is calculated and consecutive individual glottal cycles are identified in the EGG or DEGG signal. Each cycle is locally normalized in duration and amplitude, the signal values are encoded by color intensity and the cycles are concatenated to display the entire phonation in a single image, much as in sound

spectrography Spectroscopy is the field of study that measures and interprets the electromagnetic spectra that result from the interaction between electromagnetic radiation and matter as a function of the wavelength or frequency of the radiation. Matter wa ...

. The idea of wavegrams can be extended to displaying other data, such as acoustic signals or high-speed video

endoscopic An endoscopy is a procedure used in medicine to look inside the body. The endoscopy procedure uses an endoscope to examine the interior of a hollow organ or cavity of the body. Unlike many other medical imaging techniques, endoscopes are insert ...

recordings of the vibrating vocal folds.Unger, J., Meyer, T., Herbst, C. T., Döllinger, M., and Lohscheller, J. (2011). "''PVG-Wavegramm: Dreidimensionale Visualisierung von Stimmlippendynamik''", in 28. Wissenschaftliche Jahrestagung der Deutschen Gesellschaft für Phoniatrie und Pädaudiologie e. V. (Zurich, Switzerland). - http://www.egms.de/static/en/meetings/dgpp2011/11dgpp40.shtml

References

{{reflist

External links

Proceedings of the 5th International Conference on the Physiology and Acoustics of Singing (PAS5), Stockholm, Sweden

The Voice Foundation's 40th Annual Symposium: Care of the Professional Voice, 2011, Philadelphia, PA

7th International Workshop on Models and Analysis of Vocal Emissions for Biomedical Applications (MAVEBA), August 2011, Firenze, Italy
Voice technology Human voice