Multimedia Forensics: Voice Analysis and Vocal Apparatus Basics

UGC-NET Forensic Science Unit VIII drill on voice analysis and the vocal apparatus. Covers the anatomy of speech production from the lungs and trachea through the larynx, vocal folds, pharynx, oral cavity, and nasal cavity, the source-filter theory of phonation (Fant, 1960), fundamental frequency (F0) and its gender-typical ranges (male 85-180 Hz, female 165-255 Hz), and the formant structure (F1 through F4) that encodes vowel identity and speaker characteristics. The voice spectrogram (sonogram) is examined including the Bell Labs sonograph introduced by Potter, Kopp, and Green in 1947 through "Visible Speech", and the contrast between wide-band and narrow-band display modes and what each reveals about time detail versus harmonic structure.

The forensic phonetics module covers phoneme inventory variation across Indian languages including Hindi, Tamil, and Bengali, prosodic features such as pitch, stress, rhythm, and duration, inter-speaker versus intra-speaker variation, and recording standards for casework (minimum 8 kHz sample rate, 16-bit depth). Indian institutional context includes the audio-forensics units of the Central Forensic Science Laboratories at Hyderabad, Chandigarh, and Kolkata, and the professional guidelines of the International Association for Forensic Phonetics and Acoustics (IAFPA) and the European Network of Forensic Science Institutes (ENFSI).

Topics covered:

• Vocal apparatus anatomy: lungs, trachea, larynx, vocal folds, pharynx, oral and nasal cavities
• Source-filter theory: phonation source and vocal-tract resonance filter
• Fundamental frequency (F0) and gender-typical pitch ranges
• Formants F1 through F4 and their role in vowel and speaker identification
• Voice spectrogram (sonogram): axes, wide-band vs narrow-band, forensic "voice print"
• Bell Labs sonograph (Potter, Kopp, Green 1947) and "Visible Speech"
• Phonemes, prosody, inter-speaker and intra-speaker variation
• CFSL audio units; IAFPA and ENFSI guidelines; forensic recording standards

Calibrated for first-pass UGC-NET Forensic Science Paper II preparation and NFSU MSc Forensic Science entrance revision. Allow 30 minutes.