![]() The testers in this article are making sure that if a voice quality sounds disordered, the numbers consistently reflect this when compared with numbers from a normal sounding voice.Ĭepstral peak prominence is an emerging measure for acoustic analysis. Just know that the sound signal is being analyzed in different ways and tested to determine if the numbers accurately reflect what is heard perceptually. If these are unfamiliar terms, that’s okay. It takes into consideration 6 parameters: shimmer local, shimmer local dB, harmonics-to-noise ratio, general slope of spectrum, tilt of regression line through the spectrum and smoothed cepstral peak prominence. What if we could somehow combine how we measure both connected speech and prolonged vowels? Youri Maryn, Marc De Bodt and Nelson Roy developed a protocol that is multifaceted, like a diamond. The voice has many layers and dimensions, so shouldn’t it be analyzed the same way? It’s called the Acoustic Voice Quality Index. Speech contains rapid voice onsets, offsets, inflections, stress, pauses, voiced and non voiced sounds. 2) Sustained vowels are not as multidimensional as speech. There are reasons for this: 1) Adductor spasmodic dysphonia sounds relatively normal during a sustained “ahh” but is very apparent during connected speech. These measures are limited because they require the person to sustain a vowel to capture data, and that can be difficult for some voice patients. While it is important to measure sustained vowel productions, but it is vital to measure the voice in connected speech as well. Noise-to-harmonic ratio is simply comparing the relationship of good sounds to bad ones, and if the noise outweighs the harmonies, then there is dysphonia. Jitter is displacement in frequency periods or pitch variations, and shimmer is changes in intensity or amplitude. Many clinicians utilize acoustic measures like Jitter and Shimmer, as well as noise-to-harmonic ratio when they gather data. The perceptual scales are measurable, however they are subject to intra and inter rater reliability issues because on any given day each of us hears things differently. Insurance companies tend to prefer hard numbers and measurable data. Unfortunately, we can’t just say someone sounds dysphonic and expect the service to be covered. (It’s a rating scale for Frequency, Intensity, Timing and Quality on a 0-3 rating.) There are self-perception measures like the Vocal Handicap Index and the Reflux Symptom Index. ![]() How do we prove this? There are perceptual scales, like the CAPE-V and the GRBAS, and I use the Vanderbilt FITQ scale. Why does a voice sound disordered? Does it sound harsh? Does it sound breathy? Does it sound too high pitched? We can hear a voice and perceptually tell that it sounds unnatural.
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