Hafsa Ouajdi, Oussama Hadder, Mathieu Lagrange, Laurie M. Heller
Contact: mathieu dot lagrange at ls2n dot fr

Abstract

With the ever-rising quality of deep generative models, it is increasingly important to be able to discern whether the audio data at hand has been recorded or synthesized. While the detection of fake speech signals has been studied extensively, this is not the case for the detection of fake environmental audio.
We propose a simple and efficient pipeline for detecting fake environmental sounds based on the CLAP audio embedding. We evaluate this detector by using audio data from the 2023 DCASE challenge task on Foley sound synthesis.
Our experiments show that fake sounds generated by 44 state- of-the-art synthesizers can be detected with 98% accuracy on average. We show that using an audio embedding learned on environmental audio is beneficial over a standard VGGish one as it provides a 10 % increase in detection performance. Informal listening to Incorrect Negative examples demonstrates audible features of fake sounds missed by the detector such as distortion and implausible background noise.

Detection of Deepfake Environmental Audio

Our proposed system for audio fake detection is based on a multilayer perceptron (MLP) model. Instead of feeding the audios directly to our detector, we use the embeddings generated by different systems. The figure below shows an overview of the pipeline used in the experiments for the Deepfake detection, with a representation of the MLP’s network architecture. The value of dim depends on the embedding method used.

Trulli

Experimental code is available at this github repo.

Sound examples

The following samples allow you to listen to incorrect positives (Nonfake sounds that the detector classifies as fake).

Sound cue Sound example Class sound
Wrong category sounds (sneeze with snore at end) Sneeze cough
Maybe it were foley recordings footstep
Mostly noise footstep
background noise that sounds whistly Dog bark
Repetitive sound footstep
Echoes that we know are real, but system thinks are fake Sneeze cough

The following samples allow you to listen to incorrect negatives (fake sounds that the detector classifies as nonfake)

Sound cue Sound example Class sound System
Wrong category, gunshot sounds like footstep footstep footstep TrackA system08
Single brief event keyboard TrackA system11
background noise that sounds unsual keyboard TrackB system27
Repetition of a section moving Motor TrackB system09
Overlapping Repetition is easy to hear footstep TrackB system24
Difficut to discern if unrealistic noise is frim saturation/clipping or fake moving Motor TrackB system30
Artificial coughts have no emotion, sound robotic sneeze cough TrackA system02

The following samples allow you to listen to distorted targets

Sound cue Sound example Class sound System
Distortion in the target sound sneeze cough Track A system03
Distorted sound keyboard Track B sys28
Bad temporal pattern for footsteps and unrealistic background noise footsteps Track B System24
Unrealistic foreground noise moving motor vehicle Track B System09
Strong artefacts leading to rain drops perceived as gunshots rain Task A System02
Unrealistic echoes gunshots Track A system08

Accuracy Matrices

The matrices below show the accuracy per class (the x-axis) and per system (the y-axis, Track-system) for several embeddings

VGGish

MS-CLAP

PANN 32k

PANN Wavegram-logmel