Acoustic analysis of the effect of personal protective equipment on speech understanding: lessons for clinical environments.

OBJECTIVE: The use of various types of filtering facepiece class 3 (FFP3) mask have become commonplace since the Covid-19 outbreak. These have been evaluated in terms of efficacy regarding aerosol filtration but less emphasis has been placed on the acoustic effects of such masks and their consequences for clinical communication. DESIGN: A microphone 65 cm from a sound-producing Head and Torso Simulator (wearing the masks) was used to measure attenuation via a tone sweep. Predicted impact on speech reception in noise was assessed by weighting the attenuations of cochlear excitation patterns by the frequency importance function of the Speech Intelligibility Index. STUDY SAMPLE: We evaluated acoustic attenuation properties of seven FFP3 masks and a Type IIR surgical mask (as a comparator). RESULTS: The Type IIR mask had the smallest impact on SNR (2.6 dB with visor). Most FFP3s with an addition of a visor (if not already face covering) impacted SNR by approximately 6 dB. The 3 M 6000 was significantly worse (15.8 dB). CONCLUSIONS: Mouth-and-nose covering FFP3s masks had similar effects on SNR (≈6.2 dB with visor). The Tecmen TM-H2 had several advantages over other masks evaluated. It was reusable, allowed lipreading clues and the attenuation was similar to other FFP3s.

Unilateral crosstalk cancellation in normal hearing participants using bilateral bone transducers.

It is possible to psychophysically measure the phase and level of bone conducted sound at the cochleae using two bone transducers (BTs) [Mcleod and Culling (2019). J. Acoust Soc. Am. 146, 3295 - 3301]. The present work uses such measurements to improve masked thresholds by using the phase and level values to create a unilateral crosstalk cancellation system. To avoid changes in the coupling of the BT to the head, testing of tone and speech reception thresholds with and without crosstalk cancellation had to be performed immediately following the measurements without adjustment of the BT. To achieve this, a faster measurement method was created. Previously measured phase and level results were interpolated to predict likely results for new test frequencies. Testing time to collect the necessary phase and level values was reduced to approximately 15 min by exploiting listeners' previous measurements. The inter-cochlear phase difference and inter-cochlear level difference were consistent between experimental sittings in the same participant but different between participants. Addition of a crosstalk cancellation signal improved tone and speech reception thresholds for tones/speech presented with one BT and noise presented on the other by an average of 12.1 dB for tones and 13.67 dB for speech.

Psychoacoustic measurement of phase and level for cross-talk cancellation using bilateral bone transducers: Comparison of methods.

Two bone-conduction hearing aids (BCHAs) could deliver improved stereo separation using cross-talk cancellation. Sound vibrations from each BCHA would be cancelled at the contralateral cochlea by an out-of-phase signal of the same level from the ipsilateral BCHA. A method to measure the level and phase required for these cancellation signals was developed and cross-validated with an established technique that combines air- and bone-conducted sound. Three participants with normal hearing wore bone transducers (BTs) on each mastoid and insert earphones. Both BTs produced a pure tone and the level and phase were adjusted in the right BT in order to cancel all perceived sound at that ear. To cross-validate, one BT was stimulated with a pure tone and participants cancelled the resultant signal at both cochleae via adjustment of the phase and level of signals from the earphones. Participants achieved cancellation using both methods between 1.5 and 8 kHz. Levels measured with each method differed by <1 dB between 3 and 5 kHz. The phase results also corresponded well for the cancelled ear (11° mean difference) but poorly for the contralateral ear (38.4° mean difference). The first method is transferable to patients with middle-ear dysfunction, but covers a limited frequency range.

Neck Muscle Mass Index as a Predictor of Post-Laryngectomy Wound Complications.

OBJECTIVE: We investigated the relationship between paravertebral muscle cross-sectional area (PVM CSA) at the third vertebra (C3) level using computerized tomography (CT) neck images and its relationship with complications after total laryngectomy. DESIGN: Retrospective analysis of 60 advanced laryngeal cancer patients who underwent total laryngectomy was performed. The cross-sectional areas of paravertebral neck muscles using neck CT at C3 level images obtained preoperatively were analyzed. RESULTS: A significant difference in PVM CSA between complication and no complication groups, F(1, 53 = 4.319, P = .043), was identified by ANCOVA. There were no significant differences in between-subject effects: T-stage ( F = 1.652, P = .204), body mass index ( F = 0.889, P = .35), albumin ( F = .359, P = .552), age ( F = 1.623 P = .208), and smoking ( F = 4.319, P = .41). CONCLUSION: The PVM CSA measured at C3 level on pretreatment CT may help identify patients at higher risk of postoperative wound complications after total laryngectomy and who may particularly benefit from preoperative optimization of nutritional status.

Measurements of inter-cochlear level and phase differences of bone-conducted sound.

Bone-anchored hearing aids are a widely used method of treating conductive hearing loss, but the benefit of bilateral implantation is limited due to interaural cross-talk. The present study measured the phase and level of pure tones reaching each cochlea from a single, mastoid placed bone transducer on normal hearing participants. In principle, the technique could be used to implement a cross-talk cancellation system in those with bilateral bone conductors. The phase and level of probe tones over two insert earphones was adjusted until they canceled sound from a bone transducer (i.e., resulting in perceived silence). Testing was performed in 50-Hz steps between 0.25 and 8 kHz. Probe phase and level results were used to calculate inter-cochlear level and phase differences. The inter-cochlear phase differences of the bone-conducted sound were similar for all three participants showing a relatively linear increase between 4 and 8 kHz. The attenuation characteristics were highly variable over the frequency range as well as between participants. This variability was thought to be related to differences in skull dynamics across the ears. Repeated measurements of cancellation phase and level of the same frequency produced good consistency across sessions from the same participant.

Trismus following different treatment modalities for head and neck cancer: a systematic review of subjective measures.

The aim of this review was to compare systematically the subjective measure of trismus between different interventions to treat head and neck cancer, particularly those of the oropharynx. Using The Preferred Reporting Items for Systematic Review and Meta-Analyses (PRISMA) Guidelines, Six databases were searched for the text using various terms which include "oropharyngeal/head and neck cancer", "trismus/mouth opening" and the various treatment modalities. Included in the review were clinical studies (> or =10 patients). Three observers independently assessed the papers identified. Among the six studies reviewed, five showed a significantly worst outcome with regard to the quality-of-life questionnaire scores for a radiotherapy or surgery and radiotherapy (RT) ± chemotherapy or chemoradiotherapy when compared to surgery alone. Only one study showed no significant difference between surgery alone and other treatment modalities. Subjective quality-of-life measures are a concurrent part of modern surgical practice. Although subjective measures were utilised to measure post operative trismus successfully, there was no consensus as to which treatment modality had overall better outcomes, with conflicting studies in keeping with the current debate in this field. Larger and higher quality studies are needed to compare all three treatment modalities.