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Spectral Voice Analysis

LTAS, Alpha Ratio & CSID Assessment

What This Tool Measures

LTAS (Long-Term Average Spectrum)

Averaged spectrum over the entire recording showing your voice's spectral "fingerprint." Helps visualize hyperfunctional patterns (elevated high frequencies).

Alpha Ratio (Spectral Tilt)

Ratio of energy below vs above 1000 Hz. Indicates pressed (more negative) vs breathy (more positive) phonation.

  • > 0 dB: Breathy / Hypofunctional
  • -5 to 0 dB: Normal
  • -10 to -5 dB: Slightly pressed
  • < -10 dB: Pressed / Hyperfunctional

CSID (Cepstral/Spectral Index of Dysphonia)

Multiparametric index using CPP and L/H spectral ratio (Awan et al., 2010). For connected speech, variability measures (σCPP, σL/H) are included.

  • < 10: Normal
  • 10-30: Mild dysphonia
  • 30-50: Moderate dysphonia
  • > 50: Severe dysphonia

Recording Guidelines

Best: Connected Speech (20-30 seconds)

  • • Reading passage (e.g., "Rainbow Passage")
  • • Counting from 1 to 30
  • • Natural conversation sample
  • • Enables full CSID formula with variability

Also Accepted: Sustained Vowel (3-10 seconds)

  • • Sustained /a/ at comfortable pitch
  • • Uses simplified CSID formula
  • • Good for quick screening

Drop your voice recording here

or click to browse

Supports: WAV, MP3, M4A and many more • Max: 50MB