Which type of filter is used to delete specific frequencies by specifying channels for elimination?

The band reject filter, also known as a band-stop filter, is specifically designed to eliminate a range of frequencies while allowing frequencies outside that range to pass through unaffected. This filter is particularly useful in scenarios where you want to remove specific unwanted frequencies from a signal.

For instance, if there is a known interference at a certain range of frequencies, a band reject filter will effectively suppress those frequencies, leaving the rest of the signal intact. This capability makes it advantageous in various applications, such as audio processing and telecommunications, where minimizing specific noise frequencies is essential.

While high-pass filters allow frequencies above a certain cutoff to pass and attenuate lower frequencies, and low-pass filters do the opposite by allowing lower frequencies to pass while attenuating higher ones, the band reject filter uniquely targets a precise range of frequencies for elimination, making it the correct choice for this question. The notch filter is similar but is typically utilized for removing a very narrow band of frequencies rather than broader ranges, thus providing a more focused approach to frequency elimination.