There could also be a cultural aspect of this. In English, the lower you speak, the more respectable you are. It is borderline ridiculous when you listen as a foreigner (when voices are cutting off or rattling), until I learnt how to use it myself ;) Anyway, I speak with much higher pitch in French, and perhaps the bass mic is important for English speakers, but wouldn’t have had such an effect on European radios, where, maybe in Spanish, high frequencies would be important because the faster you speak, the more interesting you are? Consonants are much more important in latin languages.