The Voice Aerobics Hi-VOLT® voice-activated bracelet was created in 2015, with the goal of providing a simple external feedback tool for Parkinson’s patients (e.g. “speak loud enough to see the light”) with resulting increase in vocal intensity. The Hi-VOLT can also serve as a feedback tool for targeted training during independent home practice, helping individuals perform vocal function exercises at a high enough level of effort to obtain some strengthening effect.

Why an External Cue?

It is well established that people with Parkinson’s disease (PWP)disease have difficulty performing skilled movement when forced to rely on internal cues versus responses guided by external stimuli. This discrepancy has been attributed to the dysfunctional basal ganglia lacking an adequate, internally generated model causing persons with PD to become overly reliant on external cues to guide skilled movement.

Hypophonia (reduced volume) is a problem for nearly 90% of PWP, and while most patients don’t accurately perceive the volume deficit that exists in their day-to-day conversational speech, most can respond to external cues with an increase in loudness. In doing so,however, they will often report: “this feels really loud, I feel like I’m shouting,” “I can’t talk like this,”  comments which illustrate the sensori-perceptual deficit that PD has caused.

During one:one speech therapy, the therapist is often providing verbal cues to the patient and depending on the approach might be saying such things as: “do it again, speak louder,” “more intent”). And while verbal cues work well in therapy, patients often leave treatment with the intent to practice at home, but in the absence of an external cue, in this case, the therapist’s feedback, they may not perform at a similarly high level of effort.

How Can Hi-VOLT® Voice-on-Light Help?

In 2015, shortly after I developed the Hi-VOLTR® light, I began to incorporate it into my initial assessments of PD patients. Around 2017, I began to record acoustic data collected at the time of the initial assessment as well as some post treatment data incorporating the Hi-VOLT light. 

I began recording the data with a few assumptions based on my experience and review of the speech literature that included:

  • Most patients with PD can be louder in response to an external cue.
  • A simple, calibrated feedback tool used during the time of the initial assessment can demonstrate a patient’s stimulability for loudness, a perceptual judgement of whether an increase in loudness yield better speech clarity, and candidacy for speech treatment.
  • A vowel duration task is a measure that appears to elicit the greatest gains as a stimulability measure but may not be the best measure indicating generalization of loudness to everyday conversational speech.
  • Improvements in vocal intensity may be task specific (i.e., reading aloud v/s sustained vowel or conversational speech, which is probably the true post tx. measure.

Method of Data Collection

  • Acoustic data was collected using LSVT Companion softwear with the microphone positioned 30cm from the patient’s body. Baseline date was collected while the patient performed 3 speech tasks: a sustained “ah”; read aloud 10 sentences (CAPE-V +4);and oral reading of the Rainbow passage.
  • Acoustic data was collected a second time with the Hi-Volt positioned 13″ from the patient’s body/mouth, and the only cue given to the patient when the task was performed: “speak loud enough to activate the light.” 
  • Audio recordings were collected while the patient read the first paragraph of the Rainbow passage, and these recording reviewed with the patient.

The Question/s:

Can external cueing using a calibrated feedback tool effectively assess stimulability for an increase in vocal intensity?

Question 1: is there a statistically significant difference in loudness (dB SPL) when the same person produces sustained phonation of a vowel (ah) without feedback compared to producing the same sustained phonation when provided with visual feedback using the Hi-VOLT® light?

Statistical analysis was performed:

Acoustic data for 98 PD patients was reviewed. The values that were measured during the two sustained phonation tasks were not normally distributed as determined by the Shapiro Wilk normality test. Subsequently, the parametric, paired-t test would not be appropriate because the values are not equally distributed about the mean. Therefore, the non-parametric equivalent to the t-test, the Wilcoxon signed rank test, was used to compare the median, or middle number of the data, when ranked in order.

Rounding up, the median loudness without feedback was 74.0 dB SPL, and the median loudness when using the Hi-VOLT was 80.0 dB SPL. The increase in loudness that occurred when the patients used the Hi-VOLT is greater than would be expected by chance, and is therefore, statistically significant. The p-value of <0.001 indicates that there is less than a tenth of a percent chance that this increase in loudness occurred by chance, meaning that the difference is highly likely to be the result of using the Hi-VOLT®

Conclusion: Statistical analysis of acoustic data appears to support what I have witnessed clinically for several years, and that is that a simple external cueing device incorporated into an initial speech/voice assessment of  individuals with Parkinson’s disease can quickly and easily demonstrate stimulability for an increase in vocal intensity and help with setting targets for treatment. Unlike verbal cues such as “speak twice as loud,” which patient’s sometimes resist, the Hi-VOLT has never been met with resistance, and a review of the audio recording by the patient helps in demonstrating what’s possible with treatment.

How Can You Use the Hi-VOLT® with Your Patients?

I typically provide patients with a Hi-VOLT® light during speech therapy treatment, regardless of the approach. I encourage patients to utilize the Hi-VOLT when performing the core exercises such as the sustained vowel task. Some patients will continue to use the Hi-VOLT during daily practice, while others will gradually titrate away from dependence on an external cue. I invite patients to take the bracelet out once a week just to re-calibrate to the level of loudness they need to be using when completing home practice.

Because the Hi-VOLT® light is housed within a bracelet, it can go with patients anywhere they go like physical therapy, boxing, or a ride in the car.

(Thank you to my friend and research colleague, Dr. Roxann Diez Gross, for her help in performing statistical analysis on collected data)


My Mission: To enlist individuals in their treatment, and help them express their personality & spirit through voice. To educate  and empower. Mary Spremulli, MA, CCC-SLP * FiTOUR® Group Exercise Instructor * Voice Aerobics® A Whole Body Approach to Voice Practice

Voice Aerobics the heART and Science of Voice Practice


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