Signal Analysis, Modelling, and Interpretation

Department of Circuit Theory, Technická 2, 166 27 Prague 6
Tel: +420 224 352 236
Fax: +420 233 339 805

Who we are

doc. Ing. Roman Čmejla, CSc.
head of the group

Ing. Jan Rusz
speech pathology

Ing. Petr Ježdík, PhD.
intracranial EEG

Ing. Radek Janča
intracranial EEG

Ing. Jiří Balach
intracranial EEG

Ing. Lukáš Bauer
physiological signals

Ing. Tomáš Havel
intracranial EEG

Ing. Jan Hlavnička
speech pathology

Ing. Tomáš Lustyk
speech pathology

Ing. Martina Nejepsová
speech pathology

Ing. Michal Novotný
speech pathology

Ing. Jan Sedlák
physiological signals

Ing. Daniel Špulák
physiological signals

Ing. Tereza Tykalová
speech pathology


Research description

Research group is focused on fundamental and applied research in biomedical engineering.

Our main scope of is aimed at the speech, biological signals, digital signal processing and machine learning with background in neurology, phoniatrics, speech therapy, and physiology.

What is it good for

The findings lead to a deeper understanding of physiological mechanism and can be helpful in the diagnosis and evaluation of efficacy.

Research projects

Analyses of speech for early diagnosis of Parkinson's disease

Speech is an important indicator of motor function and coordination and is extremely sensitive to the damage of the central nervous system. Parkinson's disease is chronic neurodegenerative disorder directly related to the loss of dopamine-generating cells in the part of the brain called Substantia nigra with a prevalence of 1-2% of people over the age of 60. The first motor symptoms, i.e. tremor, rigidity and slowness of movements, occur after the death of 60-70% of dopaminergic neurons. From this point of view, the early diagnosis is crucial for improving the quality of patient's life. Changes in speech, which can be characterized by monotony, imprecise articulation or inability to keep stable rhythm, can precede the development of motor symptoms by up to 10 years before the diagnosis. The research of our group is mainly focused on the development of new technologies based on digital signal processing methods for automatic evaluation of severity of speech disorders. These technologies represent an accurate, objective, non-invasive and inexpensive method that can serves as a useful tool for early diagnosis of CNS diseases. We further focused on research of rare hereditary disorder called Huntington's disease. This disorder is a suitable experimental model as it allows us to detect the presence of the affected gene in person and thus provide the opportunity to observe the development of disease from pre-clinical stages to onset of the first disease-related symptoms.

Analysis and processing of intracranial EEG

The epilepsy is a complex chronic neurological disorder characterized by seizures. Thirty percent of people suffering from epilepsy are pharmaco-resistant. Small number of these pharmaco-resistant patients has serious diagnosis that is in the life-threatening state or prevents the development of the children brains. Therefore, neurosurgeons resect a part of damaged brain in order to avoid patients' epileptic seizure. The exact localization of seizure onset zone is essential for successful treatment with minimal or without permanent damage of brain functions. For precise localization of this zone, the methods for analyses of intracranial EEG are used. The aim of the research is to find significant artifact in interictal, ictal and postictal state in time and frequencies domain.

Differential diagnosis in neurologic diseases based on speech

Speech disorders called dysarthria may substantially differ with respect to various neurological diseases. Type of dysarthria is closely related to position of the lesion in the brain, and therefore speech can be valuable marker for neurological localization and may be diagnostically helpful in a number of neurological disorders. For example, speech of patients with Parkinson's disease typically displays monotone intonation whereas patients with stroke are likely to exhibit contradictory speech pattern of excess pitch variation. The research of our group is mainly focused on the development of new technologies based on digital signal processing methods for identification of deviant speech dimensions such as monopitch, harshness, rapid speech, imprecise articulation and many others. We aimed at differentiation between speech of atypical parkinsonian syndromes such as progressive supranuclear palsy or multiple system atrophy. In clinical practice, the majority of patients with atypical parkinsonian syndromes develop clinical features that overlap those of Parkinson's disease, and the correct diagnosis may only became clear as disease progresses. Nevertheless, accurate and early diagnosis is essential for making decision regarding management of treatment, assessing prognosis, but also for understanding pathophysiology of underlying disease and developing possible new treatment strategies.

Evaluation of surgical and pharmacological interventions effects on speech

Although, for most of the neurodegenerative diseases, there is currently no available treatment that could stop or even slow death of the brain cells, the modern medicine offers many approaches that can alleviate the various symptoms of the diseases. These approaches include a variety of drugs, speech and rehabilitative therapy, or even surgical intervention. It is possible to effectively relieve the main motor symptoms of Parkinson's disease, i.e. tremor, rigidity and slowness of movements, using administration of the drug known as levodopa, which causes stabilization of dopamine in the brain. Most patients show a positive response to treatment allowing them to return to normal life. Another treatment option covers deep brain stimulation, a surgical intervention, whose principle is electrical stimulation of the affected part of the brain. Our research group participates in project that focused on assessment of the effect of stimulation parameters reconfiguration, including frequency and amplitude, on walking and speech. We further investigate the effects of levodopa on speech in Parkinson's disease and antipsychotics in Huntington's disease, as well as physiotherapy effectiveness concerning improvement of trunk stability and related speech alterations in patients with spinocerebellar ataxia. In the future, we would also like to aim at assessment of speech therapy, since the acoustic analysis can be consider as a valuable tool for motivation and feedback during speech therapy.

Fluency disorders in people with stuttering

Stuttering is a speech disorder in which the flow of speech is disrupted by involuntary repetitions and prolongations of sound, syllables, word, phrases, and involuntary silent pauses or blocks in which the stutterer is unable to produce sound. Speech dysfluency associated with stuttering is a great social and medical problem. Stuttering is a poorly understood communication disorder with 1% global prevalence; the onset of childhood stuttering is most frequent between a child's second and fourth birthdays, before decreasing gradually and ultimately affecting nearly 5% of the population. It is widely believed that early identification and treatment of children's developmental disorders, including stuttering, is the most efficient and effective strategy for preventing such disorders from becoming chronic, long-term disabilities. The project aims is to find methods that would be based on the analysis of stutterers' audio recordings and would be able to objectively and automatically determine the degree of speech fluency disorders. These methods could be useful for phoniatrist experts in determining of stuttering severity.

Surface EMG Signal Analysis

This research is focused on the surface electromyographic (EMG) signal analysis and modeling. Our research is aimed for testing and design methods of EMG signal processing suitable to precise onset and cessation muscle activity detection. The signal recording and interpretation of analysis results runs in cooperation with experts from the Faculty of Physical Education and Sport at Charles University in Prague. We are also interested in objectivization of muscle coordination, neurological disease diagnostics and appropriate presentation form of results.

Speech in children with developmental dysphasia

Developmental dysphasia is one of the most common disorders in children's age, which manifests in different ways - in speech, motoric movement, perception and orientation. The speech development monitoring and subsequent subjective evaluation by pediatricians or phoniatrist is the one of the methods that are used nowadays. The project aims to create an automatic classifier . a software application that would be used to the developmental dysphasia diagnostic.

Age and gender dependence of children speech

An analysis of the relationship between acoustic-phonetic aspects of speech and the speaker's age may have numerous applications. This research has been motivated by practical experience in the field of phoniatry and logopaedia. When examining children's pathological speech, there is often an effort to answer the question .What age does particular speech corresponding to., and therefore for example to estimate at what age a child's speech development stopped. Chronological age is unambiguously given by date of birth. Logopaedic age is the age estimated on the basis of acoustic-phonetic aspects of human speech.

Databases, algorithms, tools, support for research, science and teaching

These projects encompass the design of novel tools, development of digital signal processing algorithms, creation of freely-accessible databases, real-time applications, educational materials, and among others support for the other projects. The number of signal processing algorithms has been developed in the course of research. These include techniques for speech feature extraction and selection, data visualisation, classification, and regression. The results of this research including novel measurements of articulation, real-time signal processing framework in C#.NET for assessment of speech pathology (automated assessment of /s/, voice field), atlas of voice pathology, collaboration in atlas of physiology and pathophysiology, and many others.

Financial support and contracts

Our research is currently supported by several grants:

  • Acoustic Voice and Speech Analysis in Patients with Central Nervous System Disorders, Czech Science Foundation GAČR 102/12/2230, R. Čmejla (2012 - 2015)
  • Large-scale dynamics and critical transitions in neuronal networks and their role in limbic seizure genesis, Czech Science Foundation GAČR 14-02634S, P. Jiruška, (2014-2017)
  • Understanding of functional organization of temporal lobe epilepsy neuronal networks. Czech Ministry of Health IGA MZ, NT14489/2013, P. Jiruška, (2013-2015)

and also several CTU grants and research projects.


We closely work with a number of experts from various institutions and disciplines, mainly the following:

Selected publications

We published several original contributions in the world's leading international scientific journals and presented their results at several international congresses and conferences.

Here is list of papers published in journals with Impact Factor during last five years:

  • R. Janča, P. Ježdík, R. Čmejla, M. Tomasek, G.A. Worrell, M. Stead, J. Wagenaar, J.G.R. Jefferys, P. Kršek, V. Komárek, P. Jiruška, P. Marusič. (2014). "Detection of interictal epileptiform discharges using signal envelope distribution modelling: application to epileptic and non-epileptic intracranial recordings". Brain Topography.
  • J. Rusz, J. Klempíř, T. Tykalová, E. Baborová, R. Čmejla, E. Růžička, and J. Roth. (2014). "Characteristics and occurrence of speech impairment in Huntington's disease: possible influence of antipsychotic medication," Journal of Neural Transmission, 121(12 December): 655-664.
  • J. Rusz, C. Saft, U. Schlegel, R. Hoffman, S. Skodda. (2014). "Phonatory Dysfunction as a Preclinical Symptom of Huntington Disease," PLoS One, 9(11 November): e113412.
  • M. Novotný, J. Rusz, R. Čmejla, E. Růžička. (2014). Automatic evaluation of articulatory disorders in Parkinson's disease. IEEE/ACM Transactions on Audio, Speech, and Language Processing, 22(9 September): 1366-1378.
  • A. Stráník, R. Čmejla, and J. Vokřál. (2014). "Acoustic parameters for classification of breathiness in continuous speech according to the GRBAS scale," Journal of Voice, 28(5 September): 653.e9-653.e17.
  • C. Bonnet, J. Rusz, M. Megrelishvili, T. Sieger, O. Matoušková, M. Okujava, H. Brožová, T. Nikolai, J. Hanuška, M. Kapianidze, N. Mikeladze, N. Botchorishvili, I. Khatiashvili, M. Janelidze, T. Serranová, O. Fiala, J. Roth, J. Bergquist, R. Jech, S. Rivaud-Péchoux, B. Gaymard, E. Růžička. (2014). "Eye Movements in Ephedrone-induced Parkinsonism," PLoS One, 9(8 August): e104784.
  • J. Rusz, M. Megrelishvili, C. Bonnet, M. Okujava, H. Brožová, I. Khatiashvili, M. Sekhniashvili, M. Janelidze, E. Tolosa, E. Růžička. (2014). "A distinct variant of mixed dysarthria reflects parkinsonism and dystonia due to ephedrone abuse," Journal of Neural Transmission, 121(6 June): 655-664.
  • D. Špulák, R. Čmejla, R. Bačáková, B. Kračmar, L. Satrapová, P. Novotný. (2014). "Muscle Activity Detection in Electromyograms Recorded During Periodic Movements," Computers in Biology and Medicine, 47(1 April): 93-103.
  • T. Lustyk, P. Bergl, R. Čmejla. (2014). "Evaluation of disfluent speech by means of automatic acoustic measurements," Journal of the Acoustical Society of America, 135(3 March): 1457-1468.
  • T. Tykalová, J. Rusz, R. Čmejla, H. Růžičková, and E. Růžička. (2014). "Acoustic Investigation of Stress Patterns in Parkinson's Disease," Journal of Voice, 28(1 January): 129.e1-129.e8. 
  • C. Bonnet, J. Hanuška, J. Rusz, S. Rivaud-Péchoux, T. Sieger, V. Majerová, T. Serranová, B. Gaymard, and E. Růžička. (2013). "Horizontal and Vertical Eye Movement Metrics: What´s Important?" Clinical Neurophysiology, 124(11 Novemeber): 2216-2229.
  • J. Rusz, R. Čmejla, T. Tykalová, H. Ružičková, Jiří Klempíř, Veronika Majerová, Jana Picmausová, Jan Roth, and E. Růžička. (2013). "Imprecise vowel articulation as a potential early marker of Parkinson's disease: Effect of speaking task," Journal of the Acoustical Society of America, 134(3 October): 2171-2181.
  • J. Rusz, J. Klempíř, E. Baborová, T. Tykalová, V. Majerová, R. Čmejla, E. Růžička, and J. Roth. (2013). "Objective Acoustic Quantification of Phonatory Dysfunction in Huntington's Disease," PLoS One, 8(6 June): e65881.
  • J. Rusz, R. Čmejla, H. Ružičková, J. Klempíř, V. Majerová, J. Picmausová, J. Roth, and E. Růžička. (2013). "Evaluation of speech impairment in early stages of Parkinson's disease: a prospective study with the role of pharmacotherapy," Journal of Neural Transmission, 120(2 February): 319-329.
  • R. Čmejla, J. Rusz, P. Bergl, and J. Vokřál. (2013). Bayesian changepoint detection for the automatic assessment of fluency and articulatory disorders. Speech Communication, 55(1 January): 178-189.
  • J. Rusz, R. Čmejla, H. Ružičková, J. Klempíř, V. Majerová, J. Picmausová, J. Roth, and E. Růžička. (2011). "Acoustic assessment of voice and speech disorders in Parkinson's disease through quick vocal test," Movement Disorders, 26(10): 1951-1952.
  • J. Kofránek, S. Matoušek, J. Rusz, P. Stodůlka, P. Privitzer, M. Mateják, and M. Tribula. (2011). "The Atlas of Physiology and Pathophysiology: Web-Based Multimedia Enabled Interactive Simulations," Computer Methods and Programs in Biomedicine, 104(2): 143-153.
  • P. Jiruška, P. Marusič, J. G. Jefferys, P. Kršek, R. Čmejla, V. Sebronová, and V. Komárek. (2011). "Sturge-Weber syndrome: a favourable surgical outcome in a case with contralateral seizure onset and myoclonic-astatic seizures," Epileptic Disorders, 13(1): 76-81.
  • J. Rusz, R. Čmejla, H. Ružičková, and E. Růžička. (2011). "Quantitative acoustic measurements for characterization of speech and voice disorders in early untreated Parkinson's disease," Journal of the Acoustical Society of America, 129(1): 350-367.
  • J. Kofránek, and J. Rusz. (2010). "Restoration of Guyton´s Diagram for Regulation of the Circulation as a Basis for Quantitative Physiological Model Development," Physiological Research, 59(6): 897-908.
  • P. Jiruška, G. T. Finnerty, A. D. Powell, N. Lofti, R. Čmejla, and J. G. Jefferys. (2010). "Epileptic high-frequency network activity in a model of non-lesional temporal lobe epilepsy," Brain, 133(5): 1380-1390.

Responsible person: RNDr. Patrik Mottl, Ph.D.