A subsequent Rule Making procedure, instituted at the request of the AAIRO, resulted in the loosening of the audio frequency limit from 3 kHz to 5 kHz, after it was determined that the improved frequency response would increase intelligibility without increasing interference to stations operating on adjacent frequencies. Although the original proposal suggested completely eliminating the filtering, the 5 kHz standard was adopted as a compromise after the National Association of Broadcasters noted that "full-power AM radio stations routinely use 5 kHz filters to address and prevent interference among AM stations, with few significant problems".