Background: Ideal voice assessments occur in low-noise, controlled environments, but this is not always feasible. Reliable, non-invasive tools are needed for voice assessment in noisier settings to improve patient outcomes and clinical research. Contact microphones capture vocal vibrations directly from the source, offering enhanced noise resistance for use in acoustically challenging settings. While they may reduce some spectral fidelity, their noise-minimizing capability makes them valuable in specific applications. This study evaluates the reliability of contact microphone-based voice assessments within simulated acoustic hospital environments.
Methods: To assess the validity of contact microphones compared to air microphones for voice assessments, vocal tasks (sustained vowel /a:/ and continuous speech) were recorded in simulated conditions, including multiple levels and types of hospital noise and reverberation. Acoustic metrics—including fundamental frequency, intensity, jitter, shimmer, harmonics-to-noise ratio, and cepstral peak prominence—were extracted from simultaneous recordings made with different types of microphones. This approach facilitated comparisons of waveform similarity and spectral fidelity. Additionally, the reliability of these acoustic parameters was assessed using Intraclass Correlation Coefficients and Pearson’s correlations.
Results: As expected, signals captured by contact microphones are less sensitive to changes in noise levels, particularly when it comes to preserving lower frequency fidelity in high-noise environments. However, due to contact microphones' characteristics, higher frequencies are not as well represented as standard acoustic microphones. Therefore, acoustic metrics based on fundamental frequency are likely most reliable even in uncontrolled conditions when recorded using a contact microphone.
Conclusion: As vocal health assessments are increasingly utilized in various settings, studies like these are essential for developing standardized protocols. The use of contact microphones in less controlled healthcare environments presents an opportunity for practical, accessible, and affordable clinical voice assessment. These microphones are particularly well-suited for high-noise environments, such as hospitals. The simplicity and noise-resistant features of contact microphones could enhance diagnostic accuracy, allowing for the timely detection of voice disorders in environments where traditional air microphones struggle. Future research may investigate the broader use of contact microphones among various patient groups, reinforcing their value as important tools in clinical voice assessment.