Spectral Fingerprint
Definition
The characteristic frequency response profile of a recording device, including roll-off curves, resonance peaks, and self-noise level. Comparing a recording's spectral fingerprint against reference databases can link it to a device class.
- Field
- Audio forensics, device identification
- Components
- Roll-off curves, resonance peaks, self-noise level
- Use
- Linking a recording to a device class
- Compared against
- Reference recording device databases
Common questions
Can a spectral fingerprint identify one exact microphone unit?+
Generally not on its own. It typically narrows the recording to a device class or model family, since manufacturing tolerances within a model line produce similar but not always distinguishable spectral profiles.
What can distort a spectral fingerprint and mislead the comparison?+
Post-processing such as compression, equalisation, or a lossy codec reshapes the frequency response, so an examiner must confirm the recording chain before treating the spectral profile as representative of the original device.
Related terms
- Double Compression
- The condition in which a video has been encoded at least twice through a lossy codec. The term is also used loosely...
- MEMS Microphone
- A Micro-Electro-Mechanical Systems microphone: the capsule type used in virtually all modern smartphones and tablets. MEMS microphones have a characteristically flat midrange...
- Psychoacoustic Masking Model
- The perceptual model used by lossy codecs such as MP3 and AAC to decide which frequency components can be discarded or coarsely...
- Quantisation Noise
- The distortion introduced when a continuous audio signal is rounded to discrete digital values. Lossy codecs concentrate quantisation noise at predictable frequency...
- Self-Noise (Noise Floor)
- The electrical noise inherent in a microphone circuit and capsule, measured in dB(A) equivalent input noise. Different microphone types have characteristic noise...