Why Does FM Radio Sound Better Than AM?

Discover why FM radio offers better audio quality than AM, and the science behind it.

Why Does FM Radio Sound Better Than AM?
Photo by Timi David / Unsplash

If you've ever wondered why FM radio sounds better than AM, you're not alone.

The difference boils down to the way the two types of radio signals are transmitted and received.

Let's dig into the technical differences between FM and AM to understand why FM tends to provide better audio quality.

Frequency Modulation (FM) and Amplitude Modulation (AM)

FM and AM are two different methods of encoding information onto radio waves.

FM changes the frequency of the carrier wave according to the amplitude of the input signal, while AM modifies the amplitude or strength of the carrier wave.

These differences in modulation lead to distinct audio quality characteristics.

Signal Quality and Interference

FM radio generally offers higher sound quality than AM due to its resistance to electromagnetic interference.

In AM, variations in the amplitude of the signal can be more susceptible to interference from other electronic devices, such as power lines, fluorescent lights, and motors, which can introduce unwanted noise to the audio.

On the other hand, FM's frequency-based modulation allows it to deliver a cleaner sound by reducing the impact of such interference.

Bandwidth and Sound Fidelity

Another crucial factor is bandwidth.

FM radio generally has a wider bandwidth allocation than AM, allowing for a broader range of frequencies to be transmitted.

This wider bandwidth contributes to FM's ability to deliver higher-fidelity sound compared to the more limited bandwidth of AM.

Adaptability and Ranges

FM signals and receivers are generally more complex and costlier to produce but are compatible with stereo sound transmission, making them suitable for higher-quality audio.

In contrast, the simpler AM technology is more adaptable to long-range transmission, which is why it is often used for AM broadcast stations that cover large geographic areas.

Digital Advancements and Future Possibilities

With the advancement of digital technology, both FM and AM radio have undergone changes.

Digital FM radio has become increasingly common in some regions, offering even higher audio quality than traditional analog FM.

Similarly, digital AM broadcasting has been explored as a way to enhance audio fidelity and reduce signal interference.

While both FM and AM have their roles in broadcasting, FM's superior sound quality makes it the preferred choice for music and high-fidelity audio transmissions.