The goal of this observational study is to describe speech and breathing patterns in adults after acquired brain injury (ABI) and understand how these patterns relate to the presence, severity, and type of dysarthria. The main questions it aims to answer are:

• What changes in voice and breathing are observed in adults with dysarthria after ABI?
• Can combining acoustic, respiratory, and clinical assessments help identify dysarthria severity and subtype?

Participants will:

• Have their speech recorded to measure voice and articulation features, such as pitch, clarity, and the ability to sustain sounds.
• Perform breathing tests using a spirometer to assess lung function.
• Complete the Frenchay Dysarthria Assessment-2 (FDA-2), adapted to Spanish, to classify dysarthria type and severity.

About 97 to 101 participants will take part. The results will help speech therapists better detect, evaluate, and treat dysarthria in adults after brain injury.

This cross-sectional observational study aims to characterise acoustic, respiratory, and clinical speech parameters in adults with acquired brain injury (ABI) and to examine their associations with the presence and severity of dysarthria. The study is limited to baseline assessment and does not include therapeutic intervention or longitudinal follow-up.

Participants complete a standardised evaluation protocol conducted in a controlled clinical setting. All assessments are performed within a short and predefined evaluation period to minimise fatigue and contextual variability. The protocol comprises three assessment sessions: (1) acoustic and aerodynamic speech evaluation based on sustained phonation vowels /a/, /i/, /u/, /o/ and connected speech tasks; (2) objective assessment of respiratory function using spirometry; and (3) clinical assessment of dysarthria using the Frenchay Dysarthria Assessment-2 (FDA-2).

Speech recordings are obtained under standardised conditions to ensure consistency across participants and reliable extraction of acoustic measures. Respiratory assessments are performed according to established international guidelines to ensure validity and reproducibility. Data from acoustic, respiratory, and clinical assessments are analysed jointly to explore associations between phonorespiratory function and dysarthria severity in adults with ABI.

Inclusion Criteria:

• Adults aged 18 years or older at the time of enrollment.

Diagnosed with acquired brain injury (ABI), including:

• Stroke
• Traumatic brain injury (TBI)
• Brain tumor
• Ability to provide written informed consent (or via a legally authorized representative if necessary).
• Cognitive function preserved, defined as a Mini-Mental State Examination (MMSE) score ≥ 24.

Exclusion Criteria:

• History of chronic respiratory diseases, such as chronic obstructive pulmonary disease (COPD) or asthma.
• History of hearing impairments that could affect speech evaluation.
• Presence of additional neurological or neurodegenerative disorders other than the acquired brain injury.
• History of voice disorders or dysphonia prior to the acquired brain injury.
• Presence of persistent pharyngeal symptoms, such as mucus, secretions, or foreign body sensation, which may interfere with speech assessment.
• Participants unable to comply with the assessment protocol or complete the required sessions.
• Presence of apahasia that prevents participation in speech tasks, such as reading, repetition, or spontaneous speech priduction.

The study population will include adult participants aged 18 years or older with a diagnosis of acquired brain injury (ABI), including stroke, traumatic brain injury, or brain tumor. Participants will be recruited from hospitals, clinics, and patient associations in Salamanca, Spain. Both individuals with and without dysarthria secondary to ABI will be included. All participants must have preserved cognitive function (Mini-Mental State Examination score ≥ 24) and be able to provide written informed consent or have a legally authorized representative provide consent if necessary.

Participants with chronic respiratory diseases, significant hearing impairments, additional neurological or neurodegenerative disorders, pre-existing voice disorders, severe aphasia, or persistent pharyngeal symptoms will be excluded.

The sample size is estimated to be between 97 and 150 participants, considering a dysarthria prevalence of 60% in the ABI population, a 95% confidence level, and a margin of err