Evaluation of Swallowing Sound Using a Throat Microphone with an AE Sensor in Patients Wearing Palatal Augmentation Prosthesis

Abstract

An increase in the population of dysphagia patients due to an aging population has led to increased attention on examination methods based on swallowing sound as simple methods of screening aspiration. However, an issue with the conventional method of cervical auscultation is that its accuracy varies based on the examiner. Previous studies examined the use of throat microphones and acceleration sensors to examine the acoustic characteristics of swallowing sound. Nevertheless, extant studies to date did not reach a level of clinical application. This study focused on using a throat microphone that is conventionally used to measure swallowing sound and an AE sensor to measurement a high-frequency range equal to and exceeding 20 kHz (upper limit 2 MHz). The study involved measuring the sounds of swallowing water of healthy subjects and patients wearing palatal augmentation prosthesis who had done surgical operation to treat head and neck cancer with the objective of using swallowing sound for screening aspiration. Acoustic characteristics of measured swallowing sound were analyzed using probability distributions using Quantile-Quantile (Q-Q) plots and spectral analysis based on wavelet transform. The findings indicated that with respect to patients with PAP, the duration time of the swallowing sound and the Q-Q plot departure rate were both significantly higher when compared with those in healthy subjects. The analysis based on wavelet transform indicated that the AE sensor allowed measurements of waveforms at a higher frequency range when compared to those in the case of the throat microphone. Additionally, an increased frequency of higher-frequency signals was associated with patients with PAP when compared to healthy subjects. The results revealed that it is possible to measure waveforms in the high-frequency range by using the AE sensor. The findings suggested the validity of analysis of the swallowing sound based on probability distributions using the Q-Q plot to evaluate the swallowing sound.

Evaluation of swallowing ability using swallowing sounds in maxillectomy patients

“…However, 9 recordings could not be interpreted because of excessive noise, possibly caused by body movements during swallowing. To reduce noise, future studies should modify the recording method of swallowing sounds, such as the means of attaching the throat microphone or the type of microphone used …”

“…The test was performed 5 times for the healthy controls and 10 times for the maxillectomy patients (5 times with the obturator prosthesis placed and then 5 times without it). The microphone was connected to a high‐speed audio interface (Octa‐Capture; Roland Corp., Hamamatsu, Japan), and the acoustic signal was transmitted to a Computerized Speech Lab (CSL model 4500; Kay Elemetrics, Lincoln Park, NJ, USA) (Figure ) . The mono line in had a resolution of 16 bits at a sampling rate of 44.1 kHz.…”

“…However, the criteria used are based on subjective evaluation, and the examiner needs to be skilled in the procedure. More objective criteria for the detection of dysphagia have been established by utilising a microphone to investigate the acoustic characteristics of swallowing sounds . Takahashi et al investigated the optimal type of detection device for acoustic analysis of the pharyngeal swallow and the symmetry and reproducibility of swallowing sounds .…”

“…More objective criteria for the detection of dysphagia have been established by utilising a microphone to investigate the acoustic characteristics of swallowing sounds. [14][15][16][17][18][19][20][21][22][23][24] Takahashi et al investigated the optimal type of detection device for acoustic analysis of the pharyngeal swallow and the symmetry and reproducibility of swallowing sounds. 15,16 Hamlet et al 17 coupled acoustic recordings with simultaneous videofluoroscopy.…”

“…However, 9 recordings could not be interpreted because of excessive noise, possibly caused by body movements during swallowing. To reduce noise, future studies should modify the recording method of swallowing sounds, such as the means of attaching the throat microphone or the type of microphone used 20. Disadvantages of our evaluation method are needing a special device, which can constitute additional expense, and having knowledge of acoustic analyses as well as the time to conduct them.…”