MDVP (Multidimensional Voice Program) has several parameters that can assess voice quality objectively, including Base Frequency (F0), Jitter, Shimmer, NHR (Noise to Harmonic Ratio), VTI (Voice Turbulence Index), and ATRI (Amplitude Tremor Intensity Index). MDVP may provide an objective yet non-invasive and comfortable alternative to assess voice quality - and to some extent, diagnose voice-related abnormalities. The utilization of MDVP in clinical settings is quite common but using it concerning occupational health is rare, especially in Indonesia. No study had reported usage of MDVP to assess voice quality in any occupational voice user group or reported a thorough comparison of MDVP parameters between occupational and non-occupational voice users. With an increase in the realization that voice can be an essential occupational modality, MDVP may become a practical alternative modality in assessing voice quality and occupational-related voice injury in clinical settings. This study will determine any association between occupational voice users and their MDVP parameters from medical records and the MDVP database in Dr Cipto Mangunkusumo Hospital, Jakarta. The study also tries to see whether there is any value in using MDVP to assess voice quality in workers.

Data will be extracted from the MDVP database and hospital medical records. The MDVP database consists of patients examined with MDVP in the Department of ORL-HNS' Larynx-Pharynx clinic of Dr. Cipto Mangunkusumo Hospital, Jakarta.

Voice evaluation for all patients in Dr. Cipto Mangunkusuomo Hospital was done using the Multidimensional Voice Program (MDVP) 4500 produced by Kay Elemetrics Corp installed on a personal computer. The patients were asked to emit vocal sounds /" a "/ using the tone and intensity of everyday speech. The physicians are obliged to give an example first. The patient's voice was then recorded using a microphone connected to a computer with the MDVP program. Sounds were recorded in a quiet room for at least 3 seconds with the microphone 10 cm from the patient's mouth. The MDVP program will directly analyze the recorded sound. Sound recording is done 3 - 5 times, and the best sound acoustic analysis results are used as the final result. The results are then kept in the program's database inside the computer.

Patients who attend the Larynx-Pharynx clinic for MDVP evaluations are usually those who comes for post-treatment monitoring (e.g., post-laryngoplasty), had been diagnosed with a voice disorders, and or by personal or physicians' request. There are various reasons why patients are being assigned to MDVP evaluations - and all of this information will be gathered and used as a consideration during data analysis. For the sake of practicality, the researcher will only extract MDVP data from the past five years. Other considerations will be made to ensure that the data extracted will represent a reliable comparison between occupation status and how it affects MDVP parameters (see more in "Criteria for subjects"). The study will use total sampling, where all available data that fits the inclusion criteria will be used for analysis.

Inclusion criteria

• Patients had their medical records and MDVP data available in dr. Cipto Mangunkusumo Hospital, Jakarta
• Patients are active workers in Indonesia on the time of MDVP evaluation
• Patients are above the age of 18
• Patients can be either an occupational or non-occupational voice users Exclusion criteria
• Patients with incomplete occupational data
• Patient with incomplete MDVP results

Data obtained from the database will be evaluated in SPSS v20 software and analysed to produce descriptive and inferential statistics. The inferential statistics will consist of univariate analysis and bivariate analysis (between two variables). All numeric data will be tested for normal distribution using Kolmogorov-Smirnov.

Univariate analysis will be done to see the average, distribution, and frequency of all variables/outcomes which include the participants' demographic information and MDVP parameters. MDVP parameters will be presented as mean score with its standard deviation (or median with range). Bivariate analysis will be done to evaluate the significance between occupational or non-occupational users to their MDVP parameters. Differences between groups will be assessed using independent samples t-test (parametric) or Mann-Whitney (non-parametric). If possible, multivariate analysis will also be conducted using Chi-Square or Fischer test depending on the data distributions.

Inclusion Criteria:

• Patients had their medical records and MDVP data available in dr. Cipto Mangunkusumo Hospital, Jakarta
• Patients are active workers in Indonesia on the time of MDVP evaluation
• Patients are above the age of 18
• Patients can be either an occupational or non-occupational voice users

Exclusion Criteria:

• Patients with incomplete occupational data
• Patient with incomplete MDVP results

Data will be extracted from the MDVP database and hospital medical records. The MDVP database consists of patients examined with MDVP in the Department of ORL-HNS' Larynx-Pharynx clinic of Dr. Cipto Mangunkusumo Hospital, Jakarta.

Individual Participant Data will be kept in Cipto Mangunkusumo General Hospital and will only be shared upon official request to the hospital.