title: Does Cervical Muscular Contraction Affect the Measurement for Electroglottographic Perturbation Parameters?
abstract: OBJECTIVE
  The purpose was to assess whether cervical muscular contraction during phonation influences the period and amplitude perturbation quotients (PPQ and APQ, respectively) of electroglottographic (EGG) signals, and whether high-pass filtering can attenuate these effects.
  
  
  METHODS
  Prospective.
  
  
  METHODS
  We included 19 nondysphonic speakers and 21 patients with muscle tension dysphonia. During the recording of acoustic and EGG signals, each participant was instructed to naturally phonate sustained vowels /i:/ and /a:/ (NP tasks), and additionally, each nondysphonic participant was asked to phonate the same vowels in a nondysphonic voice quality while contracting the cervical muscles (muscular contracted phonation [MCP] tasks). To confirm the contraction, surface and needle electromyography (EMG) was performed. The EGG signals were high-pass filtered at different cutoff frequencies from 0 to 90 Hz and were subsequently analyzed for the PPQ and APQ.
  
  
  RESULTS
  Compared with the NP tasks, the MCP tasks enhanced the cervical EMG activities ranging from 0 to more than 1000 Hz, but conferred only low-frequency noise to the EGG signals under 50 Hz and increased the values for EGG-APQ, but not EGG-PPQ. These EGG-APQ values exhibited gradual decreases after high-pass filtering with an increase in the cutoff frequency ranging from 0 to 50 Hz in both groups, followed by plateaus during the MCP tasks in the nondysphonic group.
  
  
  CONCLUSIONS
  The present results demonstrate that cervical muscular contraction seriously affects the EGG-APQ values for unfiltered EGG signals independent of the EMG activities and that appropriate high-pass filtering over 50 Hz can attenuate these effects.
authors: Department of Otorhinolaryngology - Head and Neck Surgery, Osaka University Graduate School of Medicine, Suita, Japan.
authors: Kiyohito
authors: K
authors: Hosokawa
authors: Department of Otorhinolaryngology - Head and Neck Surgery, Osaka University Graduate School of Medicine, Suita, Japan. Electronic address: mogawa@ent.med.osaka-u.ac.jp.
authors: Makoto
authors: M
authors: Ogawa
authors: Department of Otorhinolaryngology - Head and Neck Surgery, Osaka University Graduate School of Medicine, Suita, Japan.
authors: Toshihiko
authors: T
authors: Iwahashi
authors: Department of Otorhinolaryngology, Kinki Central Hospital of Mutual Aid Association of Public School Teachers, Hyogo, Japan.
authors: Michiko
authors: M
authors: Hashimoto
authors: Department of Otorhinolaryngology - Head and Neck Surgery, Osaka University Graduate School of Medicine, Suita, Japan.
authors: Hidenori
authors: H
authors: Inohara
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D016022:Case-Control Studies; D055154:Dysphonia / Q000503:physiopathology*; D004568:Electrodiagnosis; D005931:Glottis / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009119:Muscle Contraction; D009334:Neck Muscles / Q000502:physiology*; D010699:Phonation; D011446:Prospective Studies; D055815:Young Adult
keywords: Cervical muscle; Electroglottography; Electromyography; Muscle tension dysphonia; Perturbation analysis