Voice Spectrogram (Sonogram)
Definition
Time-frequency plot of speech. Wideband (about 300 Hz analysis bandwidth) shows formants; narrowband (about 45 Hz) shows harmonics.
- Plot type
- Time-frequency representation of speech
- Wideband analysis bandwidth
- About 300 Hz
- Wideband shows
- Formants
- Narrowband analysis bandwidth
- About 45 Hz
- Narrowband shows
- Harmonics
Common questions
Why would an examiner choose a narrowband spectrogram over a wideband one?+
Narrowband analysis resolves individual harmonics and is better for tracking fundamental frequency and pitch contour, while wideband analysis smears harmonics together but resolves formant bands more clearly, so the choice depends on whether the feature of interest is voice pitch or vowel resonance.
Is voice spectrogram comparison, popularly called voiceprint analysis, treated as reliable individual identification in court?+
Its scientific standing is contested. Formant and pitch patterns are influenced by microphone, channel, health, and emotional state as well as speaker identity, so many courts and forensic bodies require it be paired with auditory-phonetic analysis and treat conclusions cautiously rather than as a unique fingerprint match.
Related terms
- FASR
- Forensic Automatic Speaker Recognition. Likelihood-ratio framework using statistical speaker models (GMM, i-vectors, x-vectors).
- Formants (F1, F2, F3, F4)
- Resonant frequencies of the vocal tract that shape vowel quality. F1 and F2 together distinguish vowels (for example /i/ has low F1...
- Fundamental Frequency (F0)
- Rate of vocal-fold vibration during voiced speech, perceived as pitch. Typical adult male 80 to 180 Hz, adult female 165 to 255...
- Likelihood Ratio (LR)
- The ratio of two conditional probabilities: the probability of the observed evidence given the prosecution's hypothesis (same source), divided by the probability...
- MFCC
- Mel-Frequency Cepstral Coefficients. The dominant acoustic feature set for automatic speaker recognition.
- Source-Filter Model
- Standard model of voice production: the glottal source (vocal-fold vibration) is filtered by the vocal-tract cavity to produce the speech signal.
- Voiceprint
- Lawrence Kersta's 1962 term for the claim that the spectrographic pattern of an individual's speech is unique enough to serve as a...