Short summary

The general subject of this PhD project is the phonetogram which records habitual voice intensity and fundamental frequency of the speaking voice, and overall capacity of the voice. Three parts are planned: Part 1 aims to validate reproducibility of the phonetogram recording procedure. Part 2 aims to establish an internationally applicable protocol for recording phonetograms. Part 3 aims to measure effects caused to the voice by non-malignant vocal cord lesions and to evaluate the consequences of a new treatment strategy including hydrodissection and cordectomy by transoral laser-assisted microsurgery. This part of the project is an integrated element of the national DANGLOT project. 

Rationale

The phonetogram is an objective assessment of voice capacity (1). It can provide essential knowledge about both healthy and pathological voices (2). Consequently this type of analysis can measure the effects and side effects of a given treatment of the voice and/or the vocal cords.

The phonetogram records and monitors a range of relevant and disease specific parameters relating to intensity, frequency, and overall capacity of the voice. The intensity and the frequency of the speaking voice are summarized in the Speech Range Profile (SRP). The overall voice capacity is expressed by the Voice Range Profile (VRP), and measures the maximal frequency and intensity ranges of the voice. The phonetogram is used internationally. However, knowledge about reliability and systematic variation is very limited and research including these aspects as well as natural changes in voice over time and observer variability is absolutely needed before the phonetogram can be fully accepted as an objective and trustable instrument for clinical use. Further, the comparison of phonetogram studies is almost impossible because consensus about "how to do the phonetogram" is missing and because uncertainties in the measurements has not been properly evaluated.

Also concerning normal values for the phonetogram examination literature is very sparse. Today the necessary software and machinery is available in the some larger voice clinics and establishment of age and gender specific control groups for VRP and SRP data has been made possible. However, only few normal materials are available in literature. Such data are urgently needed before correlations between normal and pathological voices can be done.

In Denmark a new treatment strategy including hydrodissection and cordectomy by transoral laser-assisted microsurgery (TLM) is at the present being implemented for the treatment of localized vocal cord lesions including non-neoplastic leukoplakias (NNL) and Laryngeal Intraepithelial Neoplasia (LIN). To adjust treatment intensity and indication, documentation on effects caused to the voice by the vocal cord lesions and by the TLM treatment is absolutely needed.

Objective and overall aim:

This PhD project is partly a national research project, the DANGLOT project. It has three parts. The aims are:

1. To evaluate reliability and validity of apparatus and examination procedure in "Recording a Phonetogram".
2. To establish a reliable internationally applicable protocol for recording phonetograms.
3. To measure:
1. Effects caused to the voice by non-malignant vocal cord lesions (NNL and LIN)
2. The consequences of hydrodissection and cordectomy (TLM)

Clarification of the above-mentioned elements will strengthen the quality of present clinical appliance and evidence-base. Also recording the phonetogram will be applicable for research to much greater extent.

Description of the cohort

Part 1 and 2:

We collect data from approximately 35 subjects for each of seven separate groups. There will be some reuse of data, and therefore the overall sample size is reduced.

Inclusion criteria: Healthy voice, age 18 years or older. Exclusion criteria: Former surgery or therapy relating to voice, moderate or more severe hearing loss, professional or trained singers and/or voice users, phonation time less than 5 sec, intubated within a month before the exercise, lung diseases, medicine intake or condition known to potentially affect the voice, dysphonic voice on day of recording, psychosocial conditions likely to affect adherence of the protocol. In all sub studies significance level 5 % is used for calculation of number of subjects.

Initial investigations to exclude dysphonic and/or pathological voices: Stroboscopic evaluation of the vocal folds, and recordings of reading the text "The Wind and the Sun" for randomised blinded listening by experienced Speech Language Pathologists.

Part 3.1:

Building normative reference material and comparing normal voices to the voice of patients suffering from NNL and LIN: Participants, reference data group: 80 subjects matched in age to the patient group (based on own clinical data): 20 males (40-59 years), 20 females (40-59 years),

20 males (60-80 years), and 20 females (60-80 years).

Inclusion criteria: questionnaire to ensure voice is representative for the given age. Use of tobacco must be stated.

Part 3.2:

Analysis of the voice of patients suffering from NNL and LIN, before and after TLM:

Cohort-study. Every voice in the cohort is used as its own reference and shares similarities with quasi-experiments: The post-surgery voice is compared to the pre-surgery voice.

Participants, NNL, and LIN group: 80 patients in each group. These are part of the national DANGLOT database. Histology after TLM divides the patients in different groups, among these the NNL and LIN, which can then be retrieved from the database. Follow ups are made 1 year postoperatively.

Data analyses: VRP, SRP, MDVP, VHIs, phonation quotient (phonation time and lung capacity) are analysed.

Data and biological material

Part 1 and 2:

Part 1: Initial investigations to exclude dysphonic and/or pathological voices: Stroboscopic evaluation of the vocal folds, and recordings of reading the text "The Wind and the Sun" for randomised blinded listening by experienced Speech Language Pathologists.

Specifically Part 1.1: Phonetogram: Frequency in hertz (Hz) and intensity in dB at 10 measuring points within the human voice range and limits of the technical set-up. Sound input for the experiment will be selected tones extracted from a pre-recorded voice.

Part 1.2 and 1.3: Softest and highest intensity, number of cells inside (registrations of the voice on the two axes in the phonetogram).

Part 3:

Voice analysis: The DANGLOT protocol is followed. VRP and SRP are recorded once.

Data analyses: VRP, SRP, MDVP, VHI, phonation quotient (phonation time and lung capacity) and hearing are analyzed and compared.

Collaborating researchers and departments

Department of Otolaryngology, Odense University Hospital

Institute of Clinical Research, Denmark

• Consultant and Clinical associate professor ågot Møller Grøntved
• Professor and Head of Research Christian Godballe, PhD
• PhD-student Jesper Roed Sørensen

Maersk Mc-Kinney Moller Institute, University of Southern Denmark

• Associate professor Peter Møller Juhl, MSc EE, PhD
• PhD-student and Research assistant Ellen Raben Pedersen, MSc EE