The Indo-European voiced aspirates "bʰ, dʰ, gʰ, gʷʰ", which were probably breathy voiced stops, first devoiced in initial position (fortition), then fricatized in all positions, producing pairs of voiceless/voiced fricatives in Proto-Italic: "f" ~ "β", ' ~ "ð", ' ~ ', ' ~ "" respectively. The fricatives were voiceless in initial position. However, between vowels and other voiced sounds, there are indications—in particular, their evolution in Latin—that the sounds were actually voiced. Likewise, Proto-Italic /s/ apparently had a voiced allophone in the same position.