Voice Disorders in Parkinson’s Disease: Mechanisms, Early Detection and Pathways to Improvement

Many studies show that nearly 90 percent of people with Parkinson’s disease develop speech or voice difficulties at some point during the course of the illness. This article examines the complexity of the mechanisms that allow the body to produce audible language, as well as the discomfort that arises when these mechanisms become fragile.

We will also look at how the voice reflects essential aspects of our identity and why certain vocal alterations are now considered early indicators of the disease.

Finally, we will discuss different approaches that can progressively restore more stable vocal abilities, in order to facilitate communication in daily life and to regain a clearer and more confident way of speaking.

1) How do we produce an articulated sound, and what happens when it no longer works as it used to?

Producing a sound is not a simple act. It is the result of finely tuned coordination between several systems in the body.
The lungs send air, the vocal folds in the larynx transform it into sound vibration, and the muscles of the face, tongue and lips shape this sound to turn it into speech.

This complex process requires constant adjustment of the strength, rhythm and precision of movements. This regulation is largely mediated by two chemical messengers in the brain: dopamine and noradrenaline.

If we think about it carefully, we can see that a child begins by producing simple sounds, such as crying or screaming to signal hunger, for example. Over the months, the child gradually learns to articulate words, which then evolve into increasingly complex sentences over the years.

In Parkinson’s disease or during ageing, this process often reverses. Over time, different dysfunctions appear, which science has classified into various speech disorders, briefly described below:

Phonation:
The process of producing the voice through the vibration of the vocal folds in the larynx, powered by air expelled from the lungs. In Parkinson’s disease, weakness or rigidity can reduce the power and clarity of the voice.

Hypokinetic dysarthria:
A speech disorder that is characteristic of Parkinson’s disease, caused by reduced movement (hypokinesia) of the muscles involved (larynx, tongue, lips). It manifests as a weak voice (hypophonia), a monotonous tone and imprecise articulation.

Hypophonia:
A decrease in voice volume, often observed in Parkinson’s disease. It is linked to weakness of the respiratory and laryngeal muscles and is amplified by the loss of noradrenaline and dopamine.

Articulation:
The ability to coordinate movements of the tongue, lips and jaw to form clear sounds. In Parkinson’s disease, rigidity and bradykinesia interfere with this coordination and lead to slurred or blurred speech.

Vocal monotony:
The absence of intonational variation in the voice, frequently seen in Parkinson’s disease. It is due to alterations in the neural circuits that control emotional expression and is influenced by noradrenaline.

Over time, the combination of these disorders can turn everyday life into a real ordeal when trying to be understood.

Imagine a lively conversation around a table, perhaps in a restaurant with background noise that makes listening more difficult. A sentence has to be repeated three times before the person next to you nods, perhaps out of politeness, without having really understood. This situation can become unbearable and lead to social withdrawal. It is frustrating and embarrassing both for the person who struggles to make themselves heard and for the person who struggles to understand and has to keep asking for repetitions.

Even in everyday life, a spouse has to concentrate hard to follow what is being said, the shop assistant does not quite grasp what the person wants to buy, and on the phone, communication remains difficult.

The voice loses energy and becomes weaker, more monotonous, sometimes accompanied by a slight tremor or a jerky rhythm. People often describe the impression of speaking “too softly” or “having trouble being heard”, and some are not always aware of it because the brain poorly perceives the difference between the intended loudness and the actual volume produced. This can add an extra layer of frustration, with the feeling that “no one listens” to what they have to say.

Another problem, closely linked to noradrenaline, concerns speech planning. Words come more slowly, while the person takes time to organize their thoughts. Often, the ideal moment to participate in a conversation passes before they have been able to express an opinion or contribute. Under stress, this can even lead to a freezing of speech, a sort of temporary block where no words come out. This phenomenon is sometimes associated with cognitive freezing, where one suddenly forgets what one wanted to say.

Many AtremoPlus users report a marked improvement in mental clarity, and the average increase in noradrenaline (around 26 percent) observed in studies probably plays a key role in the progress seen in speech fluency.

2) The voice as a deep reflection of our personality and emotions

The voice is one of the most direct means by which we express our emotions.

In people with Parkinson’s disease, this ability to “convey” emotion through speech gradually deteriorates. Many describe the feeling of “no longer having any tone”, as if their words had been emptied of their warmth or emotional color. This phenomenon, known in science as hypoprosody, corresponds to a reduction in the melodic and rhythmic variations that convey the emotional state of the speaker.

We can recognize a person with our eyes closed through the timbre of their voice. Losing this form of self-expression goes far beyond a simple functional inconvenience. It represents a profound challenge and affects the expression of personality and emotional states, which are essential pillars of human identity.

A voice that once vibrated with joy, sadness or anger becomes weak (hypophonia), monotonous and hesitant (hypokinetic dysarthria), depriving individuals of a key tool to communicate who they are and how they feel.

Speech is therefore much more than a mechanism for being understood. It reflects personality. In a person with Parkinson’s disease, the gradual loss of vocal modulation progressively erases emotional nuances. A warm laugh may be reduced to a flat sound, and a complaint to an indistinct murmur. This vocal monotony contributes to social isolation, because relatives struggle to decode intentions or feelings. For example, a person with Parkinson’s may wish to express frustration, but their dull voice is perceived as indifference, which obscures their deeper identity.

This disconnect between inner experience and outer expression can weaken self-esteem and intensify the feeling of being “lost” in a body that no longer reflects who one is.

The situation is alarming. Many people with Parkinson’s end up speaking less and less in order to avoid effort and frustration.

This gradual reduction in communication exacerbates social isolation, a well-known aggravating factor for depression and cognitive decline. In professional life, loss of vocal ease can become a real handicap.

Several studies have shown a correlation between the severity of vocal disorders and depressive symptoms in people with Parkinson’s disease.

A study by Al Hanai and colleagues (2018) used voice recordings to detect signs of depression through acoustic parameters and demonstrated that speech alterations are closely linked to emotional state. Other work, such as that summarized in “Motor Speech Disorders” (Duffy, 2013), highlights that the loss of intonation and the difficulty communicating often lead to frustration and social isolation, two factors that worsen depressive symptoms. The voice thus becomes a reflection of emotional and cognitive vitality. When it fades, a part of human connection fades with it.

This is why restoring the voice is much more than recovering sound volume. It means relearning how to be heard, to feel, and to exist in relation to others.

3) AI-based voice analysis: a promising non-invasive and early biomarker for Parkinson’s disease

For all those who are familiar with the obstacle course that is the diagnosis of Parkinson’s disease, the desire for a reliable, rapid and affordable method has long been present in the community of people concerned.

A survey by Parkinson’s UK reports the following: in a study of more than 2,000 people, more than one quarter (26 percent) stated that they had initially received an incorrect diagnosis, with another condition being suggested before the correct diagnosis of Parkinson’s disease was made. Conversely, false diagnoses of Parkinson’s disease are a major problem, with rates ranging from 14.5 to 30 percent depending on the context (general practitioners versus specialists, early versus advanced stages). This often leads to inappropriate prescriptions.

Until now, in the field of biomarkers, research has mainly focused on identifying reliable markers through blood tests to detect Parkinson’s disease. Tools such as clinical questionnaires, particularly the UPDRS, and imaging examinations such as DaTSCAN are the current standard to assess the situation.

However, the rise of artificial intelligence is now opening new perspectives, with methods that are more accessible, less costly, non invasive and capable of intervening much earlier, without necessarily requiring very pronounced clinical signs.

Among these new approaches, voice stands out as a promising medium.

Vocal analysis could not only become a tool for early detection of Parkinson’s disease, but also a means of longitudinal monitoring, allowing the progression of neurodegeneration to be measured continuously, non invasively and objectively, even if it does not provide the same level of detailed assessment as the UPDRS.

The possibility of earlier intervention is particularly encouraging. It would offer the opportunity to act upstream, to implement strategies that may slow down or even modify the course of degeneration, before the appearance of marked motor and cognitive symptoms and before advanced destruction of dopaminergic neurons.

How does this work in practice? The human voice, that subtle flow of sounds shaped by our emotions and movements, carries within it secrets about our neurological health. In Parkinson’s disease, vocal disturbances such as a weak, monotone or hesitant voice can appear long before the classical clinical signs, sometimes up to ten years earlier.

Artificial intelligence transforms these signals into valuable biomarkers that allow early, non invasive and accessible detection. Through automated voice analysis, AI can extract patterns that are imperceptible to the human ear, such as very small variations in frequency, amplitude or rhythm, to predict Parkinson’s disease with an accuracy that often exceeds 85 to 90 percent.

Parkinson’s disease affects the neural circuits that control fine motor skills and emotional regulation, which in turn affects phonation and articulation, well before more obvious and visible symptoms appear. Studies show that these vocal changes are a reliable prodrome, or early problem. A meta analysis published in 2025 reports a prevalence of 89 percent for hypokinetic dysarthria, often detectable at early stages.

AI is particularly effective here because it can analyze thousands of acoustic features (jitter, shimmer, harmonics-to-noise ratio and others) in seconds, compared with traditional clinical examinations that are more costly and more subjective. A systematic review of 127 studies (2025) reports a remarkable mean accuracy of 87.2 percent for AI-based voice analysis, versus 91.3 percent for imaging, but with dramatically lower cost and the possibility of access via smartphone.

Even though AI obviously cannot replace a clinical examination performed by a healthcare professional, it could play a valuable role as a pre-analysis tool, to be followed by a thorough clinical diagnosis for confirmation.

Hybrid perspectives are already being explored. Trials published in 2025 propose integrating AI-based voice analysis with the UPDRS, aiming for an accuracy rate above 95 percent by combining objectivity and comprehensiveness.

4) Rehabilitation and neuroplasticity: can we learn to speak again?

Despite the very high proportion of people with Parkinson’s disease who experience speech disorders at one time or another, nearly 90 percent according to studies, only 3 to 4 percent receive specific voice-focused treatment aimed at improving communication.

The good news is that the brain retains a remarkable capacity for adaptation, even in the face of dopaminergic neuron loss.

This capacity, known as neuroplasticity, refers to the ability of the nervous system to create new connections to compensate for deficient areas.

This is precisely the principle on which vocal rehabilitation programs such as LSVT LOUD or SPEAK OUT! are based. These programs are fortunately gaining traction worldwide to help people learn to speak again and be understood.

The central idea of these approaches is simple but powerful: to stimulate the voice intensively and consciously in order to reactivate the motor circuits of speech and strengthen the associated neural networks.

In practice, people train to speak louder, more slowly and with greater intention. This focused attention on vocal production increases brain activity in motor, sensory and auditory regions, as if the brain were relearning to “listen” to its own voice in order to control it better.

Neuroimaging research confirms that intensive vocal rehabilitation can indeed change brain activity.

A pioneering study by Narayana et al. (2010) showed that after several weeks of LSVT LOUD training, participants presented a measurable increase in activity in the motor and premotor cortex, as well as in auditory and emotional regions. These changes reflect functional reorganization of the brain and show that neuronal plasticity remains active even in Parkinson’s disease.

People can access these practices through speech and language therapists, who are experts in the rehabilitation of speech, voice, articulation and swallowing. They assess the situation and propose exercises such as LSVT LOUD (Lee Silverman Voice Treatment), which increases vocal volume and clarity in four weeks and has been found effective in about 80 percent of patients according to Cochrane data from 2025.

Complementary work by Li et al. (2021), published in Frontiers in Neuroscience, reported improved vocal quality associated with increased activation in frontal and temporal areas, suggesting better integration between auditory perception and motor control.

These findings highlight the brain’s capacity to relearn how to speak louder, more consciously and more expressively despite dopaminergic loss.

Some rehabilitation approaches now integrate additional dimensions:

• Diaphragmatic breathing, which improves control of air flow and relaxes muscles in the neck and chest.

• Therapeutic singing, which stimulates respiratory and emotional coordination while promoting the release of endorphins.

• Body-voice approaches, in which movement, rhythm and speech are trained together in order to restore overall fluidity of motor activity.

Other complementary approaches may also be used:

• Rhythmic exercises that stimulate motor and auditory circuits

• Technological aids such as voice amplifiers or applications that provide auditory feedback

Of course, one can also simply sing, in everyday life: in the shower, while walking, or facing the sea, as some orators did in antiquity. What matters most is allowing the voice to be expressed, speaking louder, training it regularly, or even joining a choir for the pleasure of shared singing or a theatre group.

With regard to the positive feedback on voice from AtremoPlus users who took part in the survey, we see two main explanations.

First, it is plausible that optimization of L dopa transport across the blood brain barrier plays a key role by improving neural signaling to the muscles involved in sound production and articulation.

However, another significant mechanism seems to emerge with the involvement of noradrenaline, whose levels increase on average by 26 percent after taking AtremoPlus. This increase, which is essential for motor coordination, could explain a substantial part of the positive reports, since the production of speech and of sentences depends strongly on this capacity.

As many users of our plant based L dopa and carbidopa preparation report, several functions improve progressively, often making it possible to resume activities that had been abandoned. It is striking that speech is frequently among these improvements.

In the end, the core message remains simple. What truly matters is that many people feel better, even if we do not yet fully understand the complexity of all the mechanisms involved.