Theses of the PhD Dissertation

EÖTVÖS LORAND UNIVERSITY OF SCIENCES FACULTY OF HUMANITIES

Doctoral School of Linguistics

Head: Prof. Dr. Janusz Bańczerowski DSc, university professor

Doctoral Programme of Hungarian Linguistics Head: Prof. Dr. Jenő Kiss, Member of the Academy

THE ROLE OF VOICE ANALYSIS IN THE RECOVERY

PROCESS OF CERTAIN OTO-RHINO-LARYNGOLOGICAL

DISEASES

Dr Zoltán Fent

Consultant: Prof. Dr. Mária Gósy DSc, university professor

Budapest 2010

1. Introduction

The most important means of human communication is speech.

In recent years quality of life has become an ever more important factor

during individual oncological interventions, thus during the treatment of

head-and neck tumors, as well.

In Hungary the number of malignant head-and-neck tumors, including

hypopharyngeal and laryngeal tumors has increased significantly. A portion

of recognized tumors can only be treated with total laryngeal extirpation.

Recently, with developing surgical techniques, the approach of functional

preservation has come to the foreground: more and more patients undergo

only partial laryngectomy, and these patients would have previously

undergone total laryngeal extirpation.

We cannot be satisfied by curing the disease, and removing the tumor in

itself: the quality of verbal communication crucially affects the patient’s

quality of life as well as his/her readaptation to civil life. If this is not

successful – considering the tight relationship between physical and mental

processes – then frustration deteriorates the recovery and survival potential

of the patient.

Facial nerve paresis – due to its obvious nature – severely damages

interpersonal relations. Starting the adequate treatment as soon as possible

depending on the etiology is extremely important with regards to recovery.

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Objectives of the dissertation:

1) To study the effect of surgical interventions performed as the

treatment for malignant laryngeal tumors on the quality of voice and

quality of life,

2) To establish the relationship between the self-assessment of speech

of partial- and total laryngeal extirpated patients and the

assessment of the listeners

3) To study the significant alterations in the quality of voice after

supracricoid horizontal laryngeal surgical intervention

4) To study the limitations of voice analysis in patients who underwent

laryngeal operations; can the self-assessment of patients’ speech

based on the quality of life test be matched with the value obtained

during their voice analysis? 

5) Will articulation change during peripheral facial nerve paresis?

6) Is there any relationship between the temporal changes of paralyzed

facial nerve excitability, and the change in results obtained during

voice analysis?

7) Which parameter(s) tested during voice analysis of which vowels are

most suitable to monitor the recovery process of facial nerve paresis?

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2. Structure of the dissertation

The dissertation consists of 14 chapters.

Chapter 1, the introduction describes the subject and its actuality, as well as

the general aim of the research.

Chapter 2 is an anatomical overview. It outlines the knowledge that is

indispensable to interpret the research summarized in the dissertation. The

first subchapter details the structure of organs involved in voice formation,

while the second subchapter discusses the facial nerve.

Chapter 3 summarizes the physiology of voice formation, as well as the

acoustic and phonetic characteristics of human voice and speech.

The first subchapter of Chapter 4 introduces everyday and experimental

testing methods of organs of speech. The second subchapter discusses the

testing methods of the facial nerve and the reasons of peripheral facial

nerve paresis, as well as the most frequent associated clinical pictures.

Chapter 5 overviews laryngeal- and hypopharyngeal surgical treatment

options. Consequences of total laryngectomy and the method of voice

rehabilitation are detailed. It also outlines laryngeal operations performed

as part of my research later presented in the dissertation.

Chapter 6 provides a literature review of the effect of partial laryngeal

operations on voice formation and speech.

Chapter 7 examines parameters influencing quality of life in patients who

underwent surgical intervention due to a laryngeal or pharyngeal tumor.

Chapter 8 describes comparative testing of the speech of patients who

underwent a partial laryngeal operation. It compares and discusses the

opinion of the listeners of the perception test and the patients’ self-

assessment grouped according to the type of surgical intervention.

Chapter 9 demonstrates the acoustic analysis of the speech sound developed

after supracricoid horizontal laryngeal resection. It investigates the reasons

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of significantly different speech production of the two types of

reconstructional options after surgery.

Chapter 10 provides a comparison of the speech of patients who underwent

laryngeal operations both on objective and subjective bases. It also

elucidates the potentials and limitations of voice analysis.

Chapter 11 details the perception tests of patients after total laryngectomy.

The self-assessment of patients communicating with esophageal speech and

of those using electrolarynx is compared with the impression of the

listeners.

Chapter 12 details the monitoring of recovery processes of facial pareses

using voice analysis. Results obtained during voice analysis are compared

with results of the widely used NET test.

Chapter 13 summarizes the results.

Chapter 14 lists the references used.

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3. Materials, methods, research subjects

In the dissertation – first in Hungary – we applied the QLQ-C30 quality of

life test of the European Organization for Research on Treatment of Cancer

(EORTC), as well as the head-and-neck-tumor specific H&N35 quality of life

test.

Statistical analyses were performed with SPSS version 13.0 and 15.0

software.

Voice analysis was performed using Praat software version 4.3, 4.4, and 4.5.

Research subjects were selected from patients treated at the Department of

Oto-Rhino-Laryngology and Head-and Neck Surgery.

4. Testing quality of life in patients who underwent a laryngeal

operation

The study included 54 patients who had undergone hemilaryngectomy,

supraglottic horizontal-, supracricoid horizontal, or supracricoid lateral

laryngeal resection or total laryngectomy, with or without voice-prosthesis

implantation.

Our objective was to establish: which parameters influence mostly general

quality of life and subjective health status in the period after the surgical

intervention.

Statistical analysis of data was performed using discriminant analysis („canonical variate analysis” = CVA). Results are represented on a biplot that

graphically illustrates the relationship of the variables and the axis (Figure 1).

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Axis 120151050-5-10-15-20-25-30-35

Axi

s 2

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TL4TL6TL3

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TL5TL2

SCL6SCL1

TLV2

SCL2SCL3SCL4SCL9SCL8

SCL5

SCL10SCL7

TLV1

TLV4

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HL3HL2HL1

SCH1HL5HL4SCH3SCH2SCH4SCH8

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SGH3SGH1SGH2SGH5SGH4

HNSE

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HNPK HNTE

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PA

DYHNFI

CO

RF2

EF

HNSO

AP

HNSW

CF

HNCO

HNWL

HNSX

HNWG

HNNU

SF

Figure 1. Discriminant analysis of parameters determining quality of life and of the type of surgical intervention in patients with pharyngeal and laryngeal tumors. Signs: parameters determining quality of life: PF2: physical functions, RF2: performing activities, EF: Emotional functions, CF: cognitive functions, SF: social functions, FA: fatigability, NV: nausea, vomiting, PA: pain, DY: dyspnoe, SL: sleeplessness, AP: anorexia, CO: constipation, DI: diarrhea, FI: financial difficulties, HNPA: pain, HNSW: swallowing, HNSE: sensory organs, HNSP: speech, HNSO: social eating, HNSC: social contacts, HNSX: sex, HNTE: teeth, HNOM: opening the mouth, HNDR: dry mouth, HNSS: sticky saliva, HNCO: coughing, HNFI: sense of disease, HNPK: pain killers, HNNU: dietary supplements, HNFE: nutrition probe, HNWL: weight loss, HNWG: weight gain; type of surgery. HL: hemilaryngectomy, SGH: supraglottic horizontal-, SCH: supracricoid horizontal-, SCL: supracricoid lateral laryngeal resection, TL: laryngectomy, TLV: voice-prosthesis implantation, the numbers indicated next to the type of surgery indicate the number of specific patients.

General health- and quality of life values correlate with the extent of

intervention. The subjective health state and quality of life of subjects

eligible for voice-prosthesis implantation is significantly higher than that of

those living without a voice-prosthesis.

After surgery, on the long run communication skills significantly influence

the patient’s quality of life. Recidivation- and metastasis free survival can

be evaluated only together with quality of life, this latter can only be

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improved by bringing organ- and function preserving oncological treatment

methods into the foreground.

5. Comparative test of speech intelligibility of patients who

underwent partial laryngeal operation using perception test

During this study we analyzed the relationship between the listeners’

opinion and self-assessment indexes for speech of quality of life tests

according to groups of the type of surgery performed. Individuals

(participants) between the age of 18 and 25 with normal hearing listened to

the voice recording containing spontaneous speech of patients. Afterwards

they evaluated the quality and the intelligibility of the speech of patients by

answering the questions of the perception test. From among the

standardized quality of life tests completed by the patients (EORTC QLQ-

C30, Head and Neck 35) we highlighted the responses that were given to the

communication skills.

The results are shown in Figure 2.

0

0,5

1

1,5

2

2,5

3

3,5

4

HL SGH SCL SCH

beszédminőségbeszédérthetőségHNSP/25

Figure 2. Listeners' evaluation and patients' self-assessment for each type of surgery (HNSP/25) HL-hemilaryngectomy, SGH-supraglottic horizontal laryngeal resection, SCL-supracricoid lateral laryngeal resection, SCH-supracricoid horizontal laryngeal resection. (beszédminőség = quality of speech; beszédérthetőség= intelligibility of speech)

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The comparisons reveal that qualification by patients and by participants do

not correlate for each type of surgery; one possible explanation is different

expectation by patients with regards to post-surgery quality of voice.

Self-assessment of speech function is influenced by the type of laryngeal

operation performed. The larger the extent of residual defect in the larynx

is, the worse the value of their evaluation is.

The results obtained demonstrate that patients who underwent partial

laryngeal operation communicate well in everyday life, and this is not only

based on self-assessment, but also on the opinion of their environment.

6. “Zönge” (tone produced by the vibration of the vocal cords) voice

formation potentials after supracricoid horizontal laryngeal

resection

Significant differences can be observed in the quality of voice of patients

who underwent supracricoid horizontal resection. Some patients are only

able to form a weak, whispering-type voice, while others produce a voice of

satisfactory volume, but hoarse. Based on our investigations performed on

the group of 11 patients, differences of the place for forming the "zönge"

voice (tone produced by the vibration of the vocal cords) constitute the

background of voice quality differences. If the epiglottis can be preserved

(CHEP), the place for forming the “zönge” voice will be between the edge of

the epiglottis and the posterior pharyngeal wall (Figure 3). If the arytenoid

region is preserved, the place of “zönge” voice formation will be between the

arytenoid region and the epiglottis (Figure 4). After a reconstruction with

epiglottis removal (CHP), in certain cases no “zönge” voice is formed at all;

air flows unarrested through the glottis (Figure 5). During their speech

these patients try to use the “friction” of the air passing through the

strictures of the hypopharynx as primary voice. In other cases of

reconstruction with epiglottis removal the place for “zönge” voice formation

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is the substitute vocal cord formed between the preserved arytenoid region

and the root of the tongue.

Figure 3. The place of “zönge” voice formation is between the epiglottis and the posterior

pharyngeal wall

Figure 4. The place of “zönge” voice formation is between the epiglottis and the arytenoid

region

Figure 5. The place for forming “zönge” voice is missing

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During the acoustic analysis of patients’ voice recordings, we established the

basic frequency, and during the examination of a sustained vowel we

measured the extent of frequency- an amplitude fluctuation, as well as the

signal/noise ratio. By comparing the results obtained with those obtained for

a voice formed with a normal larynx, we established that the harsh tone of

the voice formed with the epiglottis is explained by a higher than normal

fluctuation of frequency- and amplitude, as well as by the deterioration of

the signal/noise ratio.

7. Relationships of objective and subjective assessments of speech

in patients who underwent a laryngeal operation

In our study we examined the acoustic parameters of the speech of 95

patients operated for laryngeal- or hypopharyngeal tumors, and compared

them with answers related to quality of life of EORTC questionnaires. 10

adult males with normal larynx served as the control group.

We aimed to establish in patients who underwent various types of partial

laryngectomy or total laryngectomy due to a malignant tumor and

rehabilitated using various methods, to what extent can communication

abilities experienced by the patients be objectivized with acoustic

parameters measured during their voice analysis.

From among the responses given to the questions we pay special attention

to those that were provided related to general health state, quality of life, as

well as speech, social contacts and social functions.

From among the acoustic parameters we analyzed the phonation time,

speech rate, articulation speed, fundamental frequency, number of

detectable formants, the rate of frequency and intensity fluctuation, as well

as the signal/noise ratio. The results are shown in Table 1 and 2.

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HL SGH SCH-CHEP SCH-CHP SCL TLO TLV

„substitute vocal

cord” „friction”

General health/QOL 62 61 53 45 57 43 65

Social functions 97 94 77 67 95 64 96

Speech 29 15 49 56 32 50 39 Social

contacts 3 2 20 27 3 12 12

Table 1. Responses given to selected functions of quality of life tests. (TLO – total laryngectomy, esophageal speech or electrolarynx)

normal larynx HL SGH

SCH-CHEP SCL TLO TLV

SCH-CHP

f0 (Hz) 114 123 120,5 157 115 144 130 - jitter (%) 1,04 1,8 1,09 2,6 1,95 3,09 2,8 -

shimmer (dB) 0,28 0,78 0,36 1,36 1,13 1,2 0,78 - signal/noise

(dB) [a:] 23 16 23,4 9,6 14,4 5,4 10,4 - phonation time

(s) 17 13 16,5 12,5 12 6,25 11,5 6,5 speech rate

(vowel/s) 12,89 10,56 10,6 9,06 9,7 7,5 9,2 7,8 articulation

speed vowel/s) 13,89 12,17 11,3 10,5 11,01 9,1 10,3 10,5 Table 2. Results of voice analysis according to types of surgical intervention

There is positive correlation between the subjective self-assessment of post-

surgery voice and speech by patients and the general status of health and

quality of life.

After surgery, on the long run communication skills significantly influence

the patient’s quality of life.

The quality of speech and communication abilities of patients who

underwent laryngeal operations can be objectivized by measuring - from

among the studied acoustic parameters - the jitter, the shimmer, the

maximal phonation time and signal/noise ratio, thus the successfulness of

the various operational techniques and voice rehabilitation methods are

more easily compared (Figure 6).

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ép gé

ge HLSGH

SCH-CHEP(C

HP)

SCLTLO TLV

SCH-CHP

Általános eg./QOL

szociális funkciók

jitter (%) x10

shimmer (dB) x10

Figure 6. The relation ship of jitter and shimmer to social functions and quality of life

The rate of frequency and amplitude fluctuations is inversely proportional to the subjective quality of life: QOL/jitter - [r= -0,68, p<0,05] QOL/shimmer - [r= -0,76, p<0,05] („általános eg” = general health, „szociális funkciók” = social functions)

8. Studying esophageal speech and fundamental frequency formed

with an electric artificial larynx after total laryngectomy

During the perception test performed with the inclusion of 11 patients we

compare the impressions of the listeners of speech quality and intelligibility

with the self assessment of speech provided by total laryngeal extirpated

patients. Objectives:

To establish if there is any relationship between the assessment of the

speaker and that of the conversation partner. Are there any differences in

this respect between those using an electric larynx and those with

esophageal speech?

Based on the self-assessment of speakers, those using an electric larynx are

more satisfied with their speech and communication efficiency than those

applying esophageal speech. However, according to the assessment provided

by the listeners, esophageal speech proved to be significantly better both

with respect to speech quality and speech intelligibility. The results show

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that esophageal speech allows for a more successful communication, thus for

a more efficient re-adaptation to society.

9. Monitoring of recovery processes of facial pareses using voice

analysis

In our study we compared NET (nerve excitability testing) test results of

patients suffering from peripheral facial nerve paresis with the results of

their voice analysis, by which we monitor their voice formation.

Our objective was to establish:

• Will articulation change during peripheral facial nerve paresis?

• Is there any relationship between the results of the NET test

(excitability of the paralyzed facial nerve) and the results of voice

analysis?

• Which parameter(s) tested during voice analysis of which vowels are

most suitable to monitor the recovery process of facial nerve paresis?

• In case of the 3 examined branches (temporal, zygomatic, and

marginal mandibular) which, to what extent and in case of which

vowels show a significant relationship with the changes of NET

values?  

We asked the 30 study participant patients to repeat 1-2-syllable,

vocabulary form words containing mostly front-formed, labial articulation

vowels and sentences after hearing them read out. We randomly selected 3-

3 identical vowel from the voice recorded during patient visits. We analyzed

the 8 tested vowels from the voice record, taking care to analyze the vowel

coming from the same word or sentence when the specific patient performs

his/her next visit.

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We compared the results of the voice analysis of the voice record (F0, jitter,

shimmer, signal/noise ratio) with the NET results.

In order to show correlation when comparing the mean of the NET values

and of acoustic measurements we calculated Pearson’s correlation

coefficient. The results are shown in Table 3.

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NET value temp.

NET value zyg.

NET value marg.

NET value temp.

NET value zyg.

NET value marg.

fundamental frequency

fundamental frequency

jitter % jitter %

jitter (µs) jitter (µs)

shimmer % shimmer %

shimmer (dB) shimmer (dB)

i

signal/noise ratio (dB)

y

signal/noise ratio (dB)

NET value temp.

NET value zyg.

NET value marg.

NET value temp.

NET value zyg.

NET value marg.

fundamental frequency

fundamental frequency

jitter % jitter %

jitter (µs) jitter (µs)

shimmer % shimmer %

shimmer (dB) shimmer (dB)

i:

signal/noise ratio (dB)

y:

signal/noise ratio (dB)

NET value temp.

NET value zyg.

NET value marg.

NET value temp.

NET value zyg.

NET value marg.

fundamental frequency

fundamental frequency

jitter % jitter %

jitter (µs) jitter (µs)

shimmer % shimmer %

shimmer (dB) shimmer (dB)

ɛ

signal/noise ratio (dB)

ø

signal/noise ratio (dB)

NET value temp.

NET value zyg.

NET value marg.

NET value temp.

NET value zyg.

NET value marg.

fundamental frequency

fundamental frequency

jitter % jitter %

jitter (µs) jitter (µs)

shimmer % shimmer %

shimmer (dB) shimmer (dB)

e:

signal/noise ratio (dB)

ø:

signal/noise ratio (dB)

Table 3. Correlations of front formed, rounded vowels. A yellow field indicates which acoustic parameter change of the specific vowel correlates with NET value changes

measured on the defined facial nerve branches

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Based on the results we can establish that during facial nerve paresis

articulation changes can be observed in each case.

From among the tested parameters of voice analysis, NET test results show

correlation with fundamental frequency (F0), jitter, shimmer and the

signal/noise ratio.

From the three facial nerve branches tested by us in the majority of cases

we observed a correlation with regards to articulation change on the

zygomatic branch and on the marginal mandibular branch.

We could reveal most correlations in case of these 2 branches and for the

front formed long vowels.

For each tested vowel F0 change correlates with NET values in case of the

zygomatic branch and marginal brand.

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10. Results and Conclusions

1. In Hungary we were the first to perform a comprehensive quality of

life testing according to international standards in 2 periods on a

total number of 149 patients who underwent total- and partial

laryngectomy by using the QLQ-C30 quality of life test of the

European Organization for Research on Treatment of Cancer

(EORTC), as well as the head-and-neck-tumor specific H&N35

quality of life test. We established that on the long run

communication skills are decisive with regards to patients’ quality of

life.

2. By using the perception test we established that the larger the extent

of the defect remaining after the surgery in the larynx, the worse is

the listeners’ assessment for speech quality and speech intelligibility.

Patients who underwent partial laryngeal operation communicate

well in everyday life, and this is not only based on self-assessment,

but also on the opinion of their environment.

3. By testing the reasons of significant voice quality alterations

observed after supracricoid horizontal laryngeal operations, we

revealed potential ways of primary voice formation and their acoustic

consequences.  

4. We established that after total- or partial laryngectomy, there is a

positive correlation between the subjective assessment of post-

surgery voice and speech by patients and general status of health,

and quality of life. The quality of speech and communication abilities

of patients who underwent laryngeal operations can be objectivized

by measuring - from among the acoustic parameters - the jitter, the

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shimmer, the maximal phonation time and signal/noise ratio, thus

the successfulness of the various operational techniques and voice

rehabilitation methods are more easily compared.  

5. Even internationally we were the first to test the effect of facial

nerve paresis on articulation using the method of voice analysis.

From among the tested parameters of voice analysis, NET test

results show correlation with fundamental frequency (F0), jitter,

shimmer and the signal/noise ratio. We could reveal most

correlations in case of the front formed, long vowels.   

6. Based on the results of this research the effect of paresis severity on

articulation would worth to be investigated further with a modified

set of words. Based on the results of these studies, voice analysis

could be used in a new, practical way in the future.

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Presentations related to the dissertation Speech after total laryngectomy: the oesophageal and voice prosthesis sound Fent Z., Kiefer G., Répássy G. 4th European Congress of Oto-Rhino-Laryngology Head and Neck Surgery Berlin, 2000. Tapasztalataink a percutan endoscopos gastrostoma alkalmazásával előrehaladott fej-nyaki tumoros betegeken Lőrincz T., Fent Z., Szirmai Á., Répássy G. Fül-orr-gégegyógyászat 2003/2.109-113. Az életminőséget meghatározó paraméterek garat és gégerákos betegeknél Fent Z., Kiefer G., Jósa V., Répássy G. MFOE 39. Kongresszusa, 2004. május 26-29., Sopron A supracricoid horisontalis gégeresectio utáni beszédhang akusztikai analízise Kiefer G., Fent Z., Répássy G.: MFOE 39. Kongresszusa, 2004. május 26-29., Sopron Supracricoid lateralis gégeresectio után képzett hang akusztikai analízise Kiefer Gábor dr., Fent Zoltán dr., Bajnóczyné Szucsák Klára, Répássy Gábor dr. MFFLT és a MAGYE Kongresszusa, 2004. június 24-26., Pécs A hangrehabilitáció eredményeinek összehasonlító fonetikai vizsgálata Kiefer G., Fent Z.,Gósy M. VII. Nemzetközi Magyar Nyelvtudományi Kongresszus, 2004. augusztus 29-31. MTA, Budapest Factors Defining Quality of Life in Patients with Pharyngeal and Laryngeal Cancer (poster) Fent, Zoltan; Kiefer, Gabor; Josa, Valeria; Repassy, Gabor; 5th European Congress of Oto-Rhino-Laryngology Head and Neck Surgery, Rhodos, 2004.

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Comparative Acoustic Analysis of the Voice Rehabilitation After Partial and Total Laryngectomy Kiefer, Gabor; Fent, Zoltan; Repassy, Gabor; 5th European Congress of Oto-Rhino-Laryngology Head and Neck Surgery, Rhodos, 2004. A beszéd objektív és szubjektív minősítésének összefüggései gégeműtötteknél Fent Zoltán – Kiefer Gábor – Gósy Mária XV. Magyar Alkalmazott Nyelvészeti Kongresszus Miskolc, 2005. április 7-9. Részleges- és teljes gégeeltávolításon átesett betegek beszédakusztikai paraméterei, szubjektív beszédminősége Fent Zoltán – Kiefer Gábor – Gósy Mária MFFLT és a MAGYE Kongresszusa, 2005. június 16-18., Kőszeg A gége betegségei és a zöngeképzés Fent Zoltán PhD kurzus előadás, 2005.november 17., ELTE BTK Fonetika Tanszék Részleges gégeműtéten átesett betegek nyelési funkciója Fent Zoltán dr, Bajnócziné Szucsák Klára, Tóth Krisztina dr., Szabó Balázs dr., Répássy Gábor dr. MFFLT és a MAGYE Kongresszusa, 2006. június 22-24., Hódmezővásárhely Részleges gégeműtéten átesett betegek nyelés rehabilitációja Bajnócziné Szucsák Klára, Fent Zoltán dr., Halmos György dr., Répássy Gábor dr. MFFLT és a MAGYE Kongresszusa, 2006. június 22-24., Hódmezővásárhely Eltérő fonációjú beszédmódok percepciós vizsgálata Markó Alexandra, Gráczi Tekla Etelka, Fent Zoltán dr. MFFLT és a MAGYE Kongresszusa, 2006. június 22-24., Hódmezővásárhely Supracricoid horisontális gégeresectio 1997 és 2006 között. Retrospektív elemzés Szabó B., Fent Z., Halmos Gy., Kiefer G., Tóth K., Répássy G. Magyar Fül-orr-gégeorvosok Egyesülete 39. Nemzeti Kongresszusa 2006. szeptember 6-9., Debrecen Parciális gégeműtétek rövid- és hosszútávú eredményeinek értékelése Tóth K., Halmos Gy., Fent Z., Szabó B., Bódis F., Répássy G. Magyar Fül-orr-gégeorvosok Egyesülete 39. Nemzeti Kongresszusa 2006. szeptember 6-9., Debrecen

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Parciális gégeműtéten átesett betegek életminőségének vizsgálata Halmos Gy., Tóth K., Fent Z., Szabó B., Bajor B., Répássy G. Magyar Fül-orr-gégeorvosok Egyesülete 39. Nemzeti Kongresszusa 2006. szeptember 6-9., Debrecen Gége- és hypopharynxtumoros betegek életminőségének összevetése beszédakusztikai paramétereivel Fent Z., Szabó B., Tóth K., Halmos Gy., Kiefer G., Répássy G. Magyar Fül-orr-gégeorvosok Egyesülete 39. Nemzeti Kongresszusa 2006. szeptember 6-9., Debrecen Image guidance offers additional benefits in the endoscopic solution of extended cranio-facial malformations. A case report Andor Hirschberg, Zoltán Fent, Károly Hrabák, Ödön Rezek, Ron von Jako, Gábor Répássy International Journal of Pediatric Otorhinolaryngology Extra Volume 1, Issue 3, September 2006, Pages 181-184 Különleges zöngeképzési módok hatása az észlelésre Markó Alexandra PhD, Gráczi Tekla Etelka,dr. Fent Zoltán Magyar Tudomány 167. évfolyam 2007/3. szám A hangképzésben részt vevő szervek anatómiája Fent Z. Magyar Foniátriai, Fonetikai és Logopédiai Társaság Kongresszusa 2007. június 21-23., Eger A klinikánkon 2004-ben bevezetett, komplex foniátriai vizsgálati protokoll alkalmazásával szerzett tapasztalataink Kiefer G., Fent Z. Magyar Foniátriai, Fonetikai és Logopédiai Társaság Kongresszusa 2007. június 21-23., Eger Részleges gégeműtéten átesett betegek beszédének összehasonlító vizsgálata percepciós teszt segítségével Fent Z., Markó A., Gráczi T.E. Magyar Foniátriai, Fonetikai és Logopédiai Társaság Kongresszusa 2007. június 21-23., Eger Beszédészlelési és beszédmegértési zavarok az anyanyelv-elsajátításban Szerk.: Gósy Mária. Fent Z. A hallószerv, a hallás folyamata, zavarok Könyvfejezet, Nikol Kkt., 2007.

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Az arcidegbénulások gyógyulási folyamatának monitorozása hanganalízis segítségével Fent Z., Bencsik B., Répássy G. Magyar Fül-orr-gégeorvosok Egyesülete 40. Nemzeti Kongresszusa 2008. október 15-18. Az arcidegbénulások gyógyulási folyamatának monitorozása hanganalízis segítségével – esetismertetés Bencsik B., Fent Z., Szirmai Á. Magyar Fül-orr-gégeorvosok Egyesülete 40. Nemzeti Kongresszusa 2008. október 15-18. Reziduális epipharynx tumor endoszkópos eltávolítása és gamma terápiája Fent Z., Szabó B., Fedorcsák I., Nagy R., Noszek L., Répássy G. Magyar Fül-orr-gégeorvosok Egyesülete 41. Nemzeti Kongresszusa 2010. október 13-16. Az arcidegbénulások gyógyulási folyamatának monitorozása hanganalízis segítségével – újabb eredmények Bódis F., Fent Z., Bencsik B., Répássy G. Magyar Fül-orr-gégeorvosok Egyesülete 41. Nemzeti Kongresszusa 2010. október 13-16. A supracricoid horisontalis gégeresectio utáni beszédhang akusztikai analízise Kiefer Gábor dr., Fent Zoltán dr., Répássy Gábor dr. Fül-orr-gégegyógyászat, megjelenés alatt Az életminőséget meghatározó paraméterek garat- és gégerákos betegeknél Fent Zoltán dr., Kiefer Gábor dr., Jósa Valéria, Répássy Gábor dr. Magyar Onkológia, megjelenés alatt

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