Why Does a 3.5mm Jack Buzz? The Impact of Magnetic Field Interference on Audio Signals

When you touch a 3.5mm jack plugged into a speaker, you might experience a strange buzzing noise.

This phenomenon occurs due to your body acting like a radio antenna, conducting signals into the input of the amplifier.

Causes of the Buzzing Noises:

The most common local source of noise is the magnetic fields generated by the power grid.

These magnetic fields cause the buzzing noise, which is typically at a frequency of 50Hz or 60Hz, depending on the country.

Amplification of Magnetic Fields:

The conductive properties of the 3.5mm jack amplifies the magnetic fields when touched, resulting in the buzzing noise being conducted into the audio signal.

Human Body as an Antenna:

The human body, being conductive, enhances the reception of these magnetic fields and modulates the audio output.

Electronic Interference:

Electronic devices and appliances in the vicinity can also emit electromagnetic interference, which further exacerbates the phenomenon.

Potential Solutions:

To mitigate this issue, using shielded cables and connectors can minimize the reception of external electromagnetic fields.

Furthermore, grounding the audio equipment effectively can reduce unwanted noise.

Ensuring that cables are kept away from sources of electromagnetic interference and are properly shielded can also help reduce buzzing

noises.