Posts tagged #Voice Analysis

Diagnoses Are Changed...There Must Be Something in the Water

It's Research Tuesday again! There may be "Something in the Water" for Carrie Underwood for her to be changed, and the same is true for the diagnosis of many voice disorders following videostroboscopic evaluation. In this recent article in the Laryngoscope, Seth Cohen (no not the one from the OC), Nelson Roy, Mark Courey and others take a look at how important Videolaryngostroboscopy (VLS) is as an evaluation tool. They did this retrospectively for patients from 2004-2008, who had been evaluated by an otolaryngologist and then had a specialty voice evaluation with a VLS component within 90 days. Findings? Half of the patients had a change in diagnosis following a VLS. HALF! That's insane. I love examining vocal folds with my strobe light and rigid endoscope, and now I love it even more. If this examination can correctly identify disorders that would have been misdiagnosed otherwise, I'll shout it from the mountain tops! Strobes matter!

Think about the otolaryngologist. He sees 20-30 patients per day, and voice complaints usually result in a quick look with a flexible endoscope through the nose. This is to determine if there is something scary or not, and to determine the depth of evaluation necessity. The ENT will then usually refer the patient to a voice specialist for a videostroboscopic examination, or do it himself if he has the training, technology and time. He makes the best call he can for the technology and time he has, and when he knows the patient will benefit from further analysis, he refers. This is efficient.

What makes a videostroboscopy so much more comprehensive?

  1. It can be recorded and reviewed multiple times to educate the patient and to share with other care providers.
  2. It is magnified greater than a flexible endoscope, so you see the laryngeal vestibule in greater detail.
  3. The strobe light allows the vocal folds to be seen in motion. This helps us evaluate the vocal folds in five ways, as well as for color and structure.

This saves us money, it saves the patient money, and it saves insurance companies money. In this study, 83% of 125 individuals who had the diagnosis of acute laryngitis had their diagnosis changed to something different. This was not the only initial diagnosis, but it showed the biggest change. Difference in diagnosis means that there were differences in treatment patterns as well. This means that PPI's were only used when necessary, surgery wasn't performed if it wasn't necessary and voice therapy may have helped in many cases. I like the otolaryngologists I work closely with because they are very conservative when they treat. We provide voice therapy and wait and watch. Vocal folds are so delicate and unnecessary surgery could make a voice quality worse than what the person was complaining of. Each case is different, but many times voice therapy can make a huge difference and even help avoid surgery.

So what was being over diagnosed? Acute laryngitis and vocal fold paresis had a higher chance of being changed as a diagnosis than chronic laryngitis. Cancer and nonspecific dysphonia had less of a chance than chronic laryngitis. The article also states that ENT's are less comfortable with diagnosing specific voice disorders unless they are very visual in presentation, so even more reason for our specialty to shine. Get out there, stay educated on interpreting and strobe, people!

Source: Change in diagnosis and treatment following specialty voice evaluation: A national database analysis. Cohen, Seth; Kim, Jaewhan; Roy, Nelson; Wilk, Amber; Thomas, Steven, & Courey, Mark. Laryngoscope, 13 Feb 2015, doi: 10.1002/lary.25192

 

Kristie Knickerbocker, MS, CCC-SLP, is a speech-language pathologist and singing voice specialist in Fort Worth, Texas. She rehabilitates voice and swallowing at her private practice, a tempo Voice Center, and lectures on vocal health to area choirs and students. She also owns and runs a mobile videostroboscopy and FEES company, Voice Diagnostix. She is an affiliate of ASHA Special Interest Group 3, Voice and Voice Disorders, and a member of the National Association of Teachers of Singing and the Pan-American Vocology Association. Knickerbocker blogs on her website at  www.atempovoicecenter.com. She has developed a line of kid and adult-friendly therapy materials specifically for voice on TPT or her website. Follow her on Pinterest, on Twitter and Instagram or like her on Facebook.

 

Shine Bright Like a Voice Analysis

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. How do we prove this? There are perceptual scales, like the CAPE-V and the GRBAS, and I use the Vanderbilt FITQ scale. (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. Unfortunately, we can't just say someone sounds dysphonic and expect the service to be covered. Insurance companies tend to prefer hard numbers and measurable 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.

Many clinicians utilize acoustic measures like Jitter and Shimmer, as well as noise-to-harmonic ratio when they gather data. Jitter is displacement in frequency periods or pitch variations, and shimmer is changes in intensity or amplitude. 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. 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. There are reasons for this: 1) Adductor spasmodic dysphonia sounds relatively normal during a sustained "ahh" but is very apparent during connected speech. 2) Sustained vowels are not as multidimensional as speech. Speech contains rapid voice onsets, offsets, inflections, stress, pauses, voiced and non voiced sounds.

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. 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. If these are unfamiliar terms, that's okay. 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. 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. 

Cepstral peak prominence is an emerging measure for acoustic analysis. (Cepstrum is spectrum with the letters rearranged, but it the calculations to find it are a bit more involved.) The more periodic a sound signal is, the more you will see a prominent cepstral peak, so we are looking for a low number to represent a dysphonic voice. The great thing about cepstral peak is that it is the only acoustic metric that shows dysphonia in sustained vowel productions and connected speech. Jitter, Shimmer and NHR are limited to the former.

Simply by using PRAAT, a free program, you can easily obtain data in a non-invasive way. Maryn et al 2010 says that there are other similar models of voice data analysis, but none utilize continuous speech and sustained vowels to determine how severe a person's dysphonia is. Maryn and team cross-validated the AVQI in 2009 with 251 subjects. This 2010 study looked at 72 voice samples, as well as 33 other samples to determine the AVQI's responsiveness to change. Acoustic measures were taken using James Hillenbrand's "SpeechTool" (another free program) and PRAAT.

AVQI was developed specifically to be widely available to those providing voice therapy with limited budgets. It's super nice to have CSL software from Kay Pentax, but for the vast majority of clinicians in hospitals, private practices, schools and clinics, budgets are tight. PRAAT can be downloaded on Mac or PC, so it is easily accessible. If you were like me, you might have been collecting data with PRAAT and SpeechTool, but with this measure you can streamline your data collection and use only one program. This saves you time and money, as well as provides you with better data. Excellent... The script necessary to complete calculations can be found in the appendix data for Maryn 2014.

So why the AVQI? Maryn and Weenink found that listeners rate sustained vowels more severely than connected speech when there is dysphonia present. I can vouch for this because my patients usually can only hear a target production in isolated sustained vowels, not in connected speech when I demonstrate both. The AVQI has also been tested across multiple languages, like Dutch and German. Studies have found that despite language differences, the measure remains reliable and valid.

The 2014 article cautions for clinicians to make sure they are accounting for environmental noise in the room as well as mobile phone interference. Recommendations are for a head-mounted condenser microphone with XLR connection as well as an external mixer soundcard to improve the quality of the audio signal and to keep it the same across patients. Remember to tilt the microphone away from the mouth and record voice sounds with a sampling frequency of at least 26kHz.

Using the AVQI has allowed me to streamline my evaluations by a few minutes, as well as show a picture representation of the voice to my patients. Visual is always good. Minutes of each day all are precious because they add up, so I hope you will read up on this available and easy-to-use option for acoustic measurements.

-ATVC

Resources: The Acoustic Voice Quality Index: Toward improved treatment outcomes assessment in voice disorders Youri Maryn, Marc De Bodt, Nelson Roy. Journal of Communication Disorders 43 (2010) 161–174

Objective Dysphonia Measures in the Program Praat: Smoothed Cepstral Peak Prominence and Acoustic Voice Quality Index. Marin, Youri & Weenink, David. J Voice. 2015 Jan;29(1):35-43. doi: 10.1016/j.jvoice.2014.06.015. Epub 2014 Dec 9.

 

Kristie Knickerbocker, MS, CCC-SLP, is a speech-language pathologist and singing voice specialist in Fort Worth, Texas. She rehabilitates voice and swallowing at her private practice, a tempo Voice Center, and lectures on vocal health to area choirs and students. She also owns and runs a mobile videostroboscopy and FEES company, Voice Diagnostix. She is an affiliate of ASHA Special Interest Group 3, Voice and Voice Disorders, and a member of the National Association of Teachers of Singing and the Pan-American Vocology Association. Knickerbocker blogs on her website at  www.atempovoicecenter.com. She has developed a line of kid and adult-friendly therapy materials specifically for voice on TPT or her website. Follow her on Pinterest, on Twitter and Instagram or like her on Facebook.