Effect of Different Viscous Foods and Liquids on Swallowing Sounds
Condition: Deglutition Disorder
MeSH terms: Deglutition Disorders
Study type: Observational

Summary: 
      This study is aimed to establish and identify the normal pattern of swallowing sounds and
      analyze swallowing sounds of different textured foods and viscous liquids in healthy subjects
      to provide clinical evidence to update dysphagia patients' food.
    

Detailed description: 
      Upon accepted and consented, the investigators will measure the neck circumference, height
      and weight of all participants. Then, a sound detection device (iASUS NT3-R Throat Mic
      Headset, CA, USA) will be attached on the participant's neck. This non-invasive and
      lightweight (2.3oz) device will record sound vibration signals using a pair of 20mm-diameter
      sound sensors. The device will record three times of swallowing sounds at three placements
      (Apleft, Apright, B) separately with participants' head-trunk in neutral position and also
      record sounds in the neck such as breathing sound, throat clearing and cough sounds. (Apleft,
      Apright) is the intersection of lateral border of trapezius muscle and intermediate line
      between the third and fourth cervical vertebrae in the posterior neck region. B is at the
      lateral cricoid cartilage in the anterolateral neck. Participants will use 5ml spoon to
      intake foods or liquids at room temperature.

      Healthy subjects will conduct the research in the Student Living Center Room 1036/1041 at
      UNMC. Healthy subjects will be required to swallow different consistency liquids and foods
      with their head-trunk in neutral position. Participants will also perform one of the
      following randomly after swallowing foods or liquids: throat clearing after coughing or cough
      after throat clearing. Before subjects start swallowing test, subjects can try several times
      if subjects want.There will be 2 sections to complete the whole process. Each section will
      take 2 hours.The device will record three times of swallowing sounds of each foods and
      liquids at three placements (Apleft, Apright, B) separately with participants' head-trunk in
      neutral position.The foods and liquids preparation are also listed at the end of this
      section.The PI and faculty advisor of the research team will be present during recording
      swallowing session.

      The sound detection device will record sounds which occur in the neck such as swallowing
      sounds, breathing sound, talking sounds, throat clearing and cough sounds when dysphagia
      patients intake foods and drinks. The conversation will also be recorded using a Sony
      recorder (ICD-SX713) in each data collection session.The voice recording will not be
      analyzed, which only provides the additional information about which foods or liquids
      subjects swallow or at which placement sensor records swallowing sounds. Recordings will be
      saved as digital sound wave files and segmented into individual anonymized clips for data
      analysis. The digital sound wave files will be achieved in the secured server at UNMC until
      completion of the data analysis, and then removed from the server.

      Aim1: Investigators will record the swallowing sound vibrations at the anterior and posterior
      neck in healthy subjects, and analyze the duration, amplitude, mean frequency and power
      spectrum of swallowing sounds generated by various viscous foods and liquids through the
      pharynx.

      Aim2: Investigators will compare the differences in sound duration, mean frequency and power
      spectrum of swallowing sounds between throat clearing and coughing in healthy subjects.

      *** *** *** *** ***

      Foods and Liquids Prepared for Healthy Subjects:

      Foods and liquids respectively are divided into 5 levels in the International Dysphagia Diet
      Standardization Initiative (IDDSI) and level 3, 4 are two overlapping levels in foods and
      drinks Level 0 (Thin liquid) All liquid can flow through syringe Level 1 (Slightly thick
      liquid) There is between 1 and 4 ml remaining Level 2 (Mildly thick liquid) There is between
      4 and 8 ml remaining Level 3 (Moderately thick liquid/ Liquidize) There is more than 8 ml
      remaining, but some liquid still flows through Level 4 (Extremely thick liquid/ Pureed) If no
      liquid flows at all Level 5 (Minced & Moist) Pressed with a fork the particles should easily
      be separated between and come through the prongs of a fork Level 6 (Soft) Sample squashes and
      does not return to its original shape when pressure is released.

      Level 7 (Regular) No texture restrictions

      Liquid Samples Preparation:

      According to drink details provided in the IDDSI, investigators will choose a food
      polysaccharide thickener xanthan gum (UPC784672647311, Anthony's, Gluten-Free, USA) to
      prepare different viscous solutions. Firstly, dispersing xanthan gum in de-ionized water at
      185 F for 10 min then carrying out solution in a 1.5 liter plastic beaker at 2000 rpm with a
      four-blade propeller (60 mm in diameter) using a 6-Speed blender (XJ-14402C, Mainstays,
      Walmart Inc., Bentonville, AR 72716) to ensure no lumping. After that, cool the solution to
      room temperature.

      Flow testing: Before flow testing, we will use 10ml water flows completely through the
      syringe (A 10 ml slip tip syringe international standards (ISO 7886-1)) within 10 seconds to
      check whether the nozzle is clear and free from any plastic residue or manufacturing defects
      that vary occasionally occur. After checking, firstly, get a stopwatch and 2 of 10ml slip-tip
      syringes. Secondly, remove the plunge from one of the syringes (Syringe A). Thirdly, cover
      the nozzle of the syringe A with finger which makes a seal. Then using another syringe B to
      add the syringe A up to the 10 ml line with fluid.

      According to gravity flowing test, we select the following drinks. Level 0 is de-ionized
      water Level 1 is xanthan gum: de-ionized water = 1oz: 5000ml Level 2 is xanthan gum:
      de-ionized water = 1oz: 4000ml Level 3 is xanthan gum: de-ionized water = 1oz: 3000ml Level 4
      is xanthan gum: de-ionized water = 1oz: 1000ml

      Food Samples Preparation:

      Fork Testing: The slots/gaps between prongs of a standard metal fork are typically in 4 mm.
      Pressure applied to the food sample is quantified by assessment of the pressure needed to
      make the thumb nail blanch noticeably to white color.

      According to food details provided in IDDSI, we will use IDDSI Flow Test (Syringe Test), Fork
      (The slots/gaps between the tines/prongs of a standard metal fork typically measure 4 mm)
      Drip Test and Fork Pressure Test selects food as follows:

      Level 5 (Minced & Moist) cereal: de-ionized water = 2:1 Dispersing xanthan gum in de-ionized
      water at 185 F for 10 min then carrying out solution in a 1.5-liter plastic beaker at 2000
      rpm with a four-blade propeller (60 mm in diameter) using a 6-Speed blender to ensure cereal
      is fully moist & minced and less than 1.5cm*1.5cm. After that, cool the solution to room
      temperature.

      Level 6 (Soft) Banana Level 7 (Regular) White bread
    

Observational model: Other
Time perspective: Cross-Sectional
Sampling method: Probability Sample
Study population: 
        The participants are between 19-60 years old and able to sign the informed consent.
        According to self-reporting no history of swallowing disorders, neurological deficits
        and/or cancer of the mouth, neck or brain, or head or neck surgery, they will be able to
        sit upright with or without back support of chair. They have no poor dentition and
        neurological conditions. They don't have other diseases like cervical spondylosis, having
        pain when swallowing like tonsil inflammation, peritonsillar abscess, retropharyngeal
        abscess, pharyngeal tumor, epiglottis abscess and other diseases of the throat. They have
        no esophageal diseases such as esophageal cancers, esophageal foreign body feelings,
        esophagitis or neuromuscular disorders such as esophageal spasm.
      
Keywords: Dysphagia; Swallowing Sound; Acoustic Analysis