AI voice detector

How voice-clone scams work

A scammer finds a few seconds of someone’s voice — a social media video, a voicemail greeting, a podcast — and feeds it to a cloning tool. The tool generates new speech in that voice from typed text. The call or voice note is designed to rush you: an accident, an arrest, a kidnapping, a boss who needs an urgent transfer before a deadline. The voice is often slightly muffled or emotional, which hides imperfections, and the request comes with a reason not to call back.

The same technology impersonates executives in “CEO fraud”, politicians in robocalls before elections, and customers when calling banks that use voice verification.

What the detector checks in a voice recording

• The format. Mono WAV files at 16, 22.05 or 24 kHz are the default output of many speech engines. Messaging-app formats are recognised and handled separately.
• A bandwidth ceiling. Speech synthesised at a low internal rate and saved into a higher-rate file shows an abrupt cut-off in the spectrum at 8, 11 or 12 kHz. Telephone bandwidth (around 3.4–4 kHz) is recognised as a different, innocent cause.
• Perfect silence. Pauses that are exact digital zero, rather than quiet room noise, are common in synthetic speech and rare in real recordings.
• Noise floor. How loud the quietest moments are. Real phones pick up hiss, traffic, wind and breath.
• Pitch smoothness and evenness. Natural voices waver from one moment to the next; many synthetic voices are smoother and hold a more even loudness.

The result lists which of these fired and in which direction. The spectrogram above the player lets you see the cut-off and the silences for yourself: a real recording usually shows a hazy floor of noise in every gap, while synthetic speech often shows pure black between words.

Better than any detector: a callback

For a suspected scam call, detection is the second line of defence. The first is verification through a channel the scammer doesn’t control: call the person back on a saved number, message them on a different app, or ask a question only they could answer. Many families now agree a code word for emergencies. Banks and employers increasingly require a second confirmation for any transfer requested by phone — insist on it.