How to Use Spectrograms to Analyse EVP Recordings

# How to Use Spectrograms to Analyse EVP Recordings

What the spectrogram tells you

Recognising voice patterns makes it easier to find potential EVP material buried in noise. Speech often appears as clustered bands in the lower-to-mid frequency range with intermittent higher-frequency elements. With practice you will spot speech-like shapes amid other sounds.

Common noise types and how they look

• White noise: appears as a uniform spread across the entire frequency range and time. It lacks distinct bands and looks like a constant smear.
• High-frequency hiss: shows as lighter areas concentrated at the top of the spectrogram.
• Low-frequency rumble: appears as energy concentrated toward the bottom.
• Pure tones: show up as narrow, continuous bands at a single frequency, for example a 7 kHz tone or a 400 Hz tone used in demonstrations.

Seeing these shapes helps you choose edits that remove unwanted frequencies while preserving voice bands.

How to isolate and clean voices

Open your recording in an audio editor that offers a spectrogram view (free options like Audacity or paid options like Adobe Audition were mentioned). Use the spectral display to:

• Identify the vertical placement of the voice and the noisy bands you want to remove.
• Highlight the specific frequency range and the time interval where the noise occurs.
• Delete or cut that selection, or reduce its volume to zero.

For narrow problems like clicks or short noises you can use targeted tools (the article mentions a 'spot healing brush' in editors that offer it) to blend edits so they sound less obvious.

• A speech example concentrated under 500 Hz but with elements up to 6 kHz shows how voices occupy multiple bands.

• Single-frequency tones (e.g. 7 kHz or 400 Hz) produce clear horizontal bands that you can remove without affecting other ranges.

Workflow tips

Repeated practice reading spectrogram patterns will make it faster to spot real speech versus random noise. The spectrogram does not prove a voice is paranormal, but it helps you isolate and clarify sounds for closer evaluation.