audio frequency that is higher than the traditional intermediate frequency (10 kHz ) and lower than the traditional high frequency (100 kHz ), for this purpose is frequency at 15 kHz to 35 kHz, sagedus, mis on kõrgem kui vahesagedus (10 kHz) ja madalam kui kõrgsagedus (100 kHz), ehk sagedus vahemikus 15 kHz kuni 35 kHz
