Which frequency range is essential for commercial quality speech transmission?

The frequency range essential for commercial quality speech transmission primarily falls within the Medium Frequency (MF) category, which typically spans from 300 kHz to 3 MHz. This range includes the frequencies used for AM radio broadcasting, which are effective for transmitting voice and sound clearly over long distances.

Using frequencies within this range ensures that the distinct characteristics of speech, such as pitch, tone, and clarity, are preserved. This is critical for effective communication, especially in commercial applications where understanding and clarity are crucial. Frequencies in the super low, very low, and low frequency ranges do not adequately support the requisite fidelity and intelligibility for speech transmission, as they are more suitable for different types of communication or applications, such as submarine communication or broadcasting over large geographical areas with less emphasis on clarity.

Therefore, the answer highlighting the Medium Frequency range aligns with the requirements for high-quality speech transmission in commercial settings.