Table 5 Correlation analysis between the age and the numerical predictors in the study group

Fundamental frequency

Controls

− 0.47

0.0092

Significant inverse correlation

Cases

− 0.24

0.1958

Insignificant correlation

Whole sample

− 0.39

0.0021

Significant inverse correlation

Mean fundamental frequency

Controls

− 0.46

0.0105

Significant inverse correlation

Cases

− 0.18

0.3438

Insignificant correlation

Whole sample

− 0.34

0.007

Significant inverse correlation

Jitter

Controls

0.46^a

0.0112^a

Significant direct correlation

Cases

0.4

0.0292

Significant direct correlation

Whole sample

0.32

0.0128

Significant direct correlation

Shimmer

Controls

− 0.04

0.8335

Insignificant correlation

Cases

0.19^a

0.3089^a

Insignificant correlation

Whole sample

0.12

0.3777

Insignificant correlation

Noise to harmonic ratio

Controls

0.33

0.0749

Insignificant correlation

Cases

− 0.23

0.2148

Insignificant correlation

Whole sample

− 0.01

0.9201

Insignificant correlation