Load data on Icelandic:

phono <- read.csv("http://math-info.hse.ru/f/2018-19/ling-data/icelandic.csv")

Look at groups of consonants:

table(phono$cons1)
## 
##  asp  fri nasp   no  vls  voi 
##  304   15  133   94  142  118

Create a boxplot for vowel duration for each group of consonants:

boxplot(phono$vowel.dur ~ phono$cons1)

Perform ANOVA:

res <- aov(phono$vowel.dur ~ phono$cons1)
res
## Call:
##    aov(formula = phono$vowel.dur ~ phono$cons1)
## 
## Terms:
##                 phono$cons1 Residuals
## Sum of Squares      96776.3  404073.9
## Deg. of Freedom           5       800
## 
## Residual standard error: 22.47426
## Estimated effects may be unbalanced

More informative summary:

# H0: there are no difference in population means by groups
summary(res)
##              Df Sum Sq Mean Sq F value Pr(>F)    
## phono$cons1   5  96776   19355   38.32 <2e-16 ***
## Residuals   800 404074     505                   
## ---
## Signif. codes:  0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1

Question: judging by the output above, can we conclude that average vowel duration differ significantly in different groups of consonants?