Yeah they were fundamental to the tuning of radio at all come to think of it. Formant filter synths were available far earlier. And even earlier than that wah-

Yeah they were fundamental to the tuning of radio at all come to think of it. Formant filter synths were available far earlier. And even earlier than that wah-wah mutes on trumpets were commonplace in the 20s which were a physical manifestation of tunable peak low pass filters: https://en.wikipedia.org/wiki/Wah-wah_(music) https://en.wikipedia.org/wiki/Wah-wah_(music)