question: Why is hearing diminished during a yawn and enhanced right after?
comment: Here’s what the google man said It is related to Eustachian tube. It links the back of throat and the middle ear and allows air pressure to equalize in the middle ear. When you yawn air pressure goes up in this and it bends the ear drum and causes impair hearing (notice, just impair and not stop). Yawning also helps to open Eustachian tube
passages: BULLET::::- The acoustic reflex is also invoked when a person vocalizes. In humans, the vocalization-induced stapedius reflex reduces sound intensities reaching the inner ear by approximately 20 decibels. The reflex is triggered in anticipation of the onset of vocalization. While the vocalization-induced stapedius reflex in humans results in an approximate 20 dB reduction in transduction to the inner ear, birds have a stronger stapedius reflex that is invoked just before the bird tweets.
  
  Section::::Protection role.
   A similar hypothesis suggests yawning is used for regulation of body temperature. Similarly, Guttmann and Dopart (2011) found, that, when a subject wearing earplugs yawned, a breeze is heard, caused by the flux of the air moving between the subject's ear and the environment. Guttmann and Dopart determined that a yawn causes one of three possible situations to occur: the brain cools down due to an influx or outflux of oxygen, the pressure in the brain is reduced by an outflux of oxygen, or the pressure of the brain is increased by an influx of air caused by increased cranial space.
   Budzynski, Stoyva, Adler, and Mullaney (1973) reported that auditory frontalis EMG biofeedback combined with home relaxation practice lowered tension headache frequency and frontalis EMG levels. A control group that received noncontingent (false) auditory feedback did not improve. This study helped make the frontalis muscle the placement-of-choice in EMG assessment and treatment of headache and other psychophysiological disorders.
  
  Section::::Applications.:Pain.:Migraine.
   BULLET::::- full recovery from TTS can be achieved in approximately two minutes
  
  BULLET::::- the TTS is relatively independent of exposure duration
  
  BULLET::::- TTS is maximal at the exposure frequency of the sound
  
  Long-term fatigue
  
  BULLET::::- recovery requires a minimum of several minutes but can take up to several days
  
  BULLET::::- dependent on exposure duration and noise level
  
  Section::::Physiology.
  
  Section::::Physiology.:Affected anatomy.
  
  Note: "The complete anatomy of the human ear is extensive, and can be divided into the inner ear and outer ear. The remainder of this article mainly references the cochlea, outer hair cells, and organ of Corti."
   A person with normal hearing can experience this by sticking their fingers into their ears and talking. Otherwise, this effect is often experienced by hearing aid users who only have a mild to moderate high-frequency hearing loss, but use hearing aids which block the entire ear canal.
   Section::::Factors.:Hearing impairment.
  
  People with mild and moderate hearing loss were tested for the effectiveness of phonemic restoration. Those with mild hearing loss performed at the same level of a normal listener. Those with moderate hearing loss had almost no perception and failed to identify the missing phonemes. This research is also dependent on the amount of words the observer is comfortable understanding because of the nature of top-down processing.
  
  Section::::Factors.:Cochlear implants.
   If this fails, then the Valsalva maneuver may be used. This maneuver, when used as a tool to equalize middle ear pressure, carries with it the risk of auditory damage from over pressurization of the middle ear. It is safer, if time permits, to attempt to open the Eustachian tubes by swallowing a few times, or yawning, or by using the Valsalva technique of breathing a very small amount of air gently into nostrils held closed by the fingers as soon as mild pressure is felt, before it increases to the point that its release would be painful. The effectiveness of the "yawning" method can be improved with practice; some people are able to achieve release or opening by moving their jaw forward or forward and down, rather than straight down as in a classical yawn, and some can do so without moving their jaw at all by activating the tensor tympani muscle, which is heard by the individual as a deep, rumbling sound. Opening can often be clearly heard by the practitioner, thus providing feedback that the maneuver was successful.
   A speaker can regulate their vocalizations, particularly their amplitude relative to background noise, with reflexive auditory feedback. Such auditory feedback is known to maintain the production of vocalization since deafness affects the vocal acoustics of both humans and songbirds Changing the auditory feedback also changes vocalization in human speech or bird song. Neural circuits have been found in the brainstem that enable such reflex adjustment.
  
  Section::::Mechanisms.:Public loop.
   BULLET::::- no control of compression setting
  
  BULLET::::- no frequency-specific compensation of hearing impairment
  
  Section::::Cochlear implantation and central auditory development.
   For people with cochlear implants, acoustic simulations of the implant indicated the importance of spectral resolution. When the brain is using top-down processing, it uses as much information as it can to make a decision on if the filler signal in the gap belongs to the speech, and with lower resolution, there is less information to make a correct guess. A study with actual cochlear implant users indicated that some implant users can benefit from phonemic restoration, but again they seem to need more speech information (longer duty cycle in this case) to achieve this.
  
  Section::::Factors.:Age.
   Section::::Physiology.:Affected mechanisms.:Traveling wave theory.:Classical passive system.
  
  There are two different systems associated with the mechanics of the cochlea: the classical passive system and an active process. The passive system works to stimulate the inner hair cells directly and works at levels above 40 dB. At stimulation levels that prevent the excitation of the passive system, prolonged noise exposure results in a decrease in the loudness heard over time, even when the actual intensity of the noise has not changed. This is caused by the exhaustion of the active process.
  
  Section::::Physiology.:Affected mechanisms.:Traveling wave theory.:Active process.
   There are many procedures followed during chamber training for aircrew. Usually new aircrew will undergo a familiarization profile, where the chamber ascends to an altitude of 10,000 ft. During the ascent they are instructed on the proper procedure to clear the ears. During ascent, students are asked to yawn and on descent they need to perform the valsalva maneuver. If they perform the valsalva during ascent, they risk suffering barotrauma of the ear. This is because the ears are susceptible to Boyle's Law.
   In addition, these extra vibrations can cause the formation of free radicals known as reactive oxygen species or ROS. Elevated levels of ROS continue to increase the metabolic demands of the system. These increasing demands fatigue the system and eventually lead to structural damages to the Organ of Corti.
  
  Section::::Physiology.:Affected mechanisms.:Recovery.
   The protection of the organ of Corti, provided by the acoustic reflex against excessive stimulation (especially that of the lower frequencies) has been demonstrated both in man and animals. But this protection effect is limited.
  
  According to the article "Significance of the stapedius reflex for the understanding of speech", the latency of contraction is only about 10ms, but maximum tension may not be reached for 100 ms or more.
   In his initial experiments, Warren provided the sentence shown and first replaced the first 's' phoneme in legislatures with extraneous noise, in the form of a cough. In a small group of 20 subjects, 19 did not notice a missing phoneme and one person misidentified the missing phoneme. This indicated that in the absence of a phoneme, the brain filled in the missing phoneme, through top-down processing. This was a phenomenon that was somewhat known at the time, but no one was able to pinpoint why it was occurring or had labeled it. He again did the same experiment with the sentence:
   BULLET::::- The effects of the pharmaceutical drug Tanakan were observed when treating tympanophonia in elderly women. Tanakan was found to decrease the intensity of tympanitis and improve speech and hearing in aged patients, giving rise to the idea of recommending treatment with it to elderly patients with presbycusis or normal tonal hearing.
   According to the article "Le traumatisme acoustique", the latency of contraction is 150 ms with noise stimulus which SPL is at the threshold (ATR), and 25-35 ms at high sound pressure levels. Indeed, the amplitude of the contraction grows with the sound pressure level stimulus.
  
  Because of this latency, the acoustic reflex cannot protect against sudden intense noises. However, when several sudden intense noises are presented at a pace higher than 2–3 seconds of interval, the acoustic reflex is able to play a role against auditory fatigue.
   When a word with the segment 's' is removed and replaced by silence and a comparable noise segment were presented dichotically. Simply put, one ear was hearing the full sentence without phoneme excision and the other ear was hearing a sentence with a 's' sound removed. This version of the phonemic restoration effect was particularly strong because the brain was doing much less guess work with the sentence, because the information was given to the observer. Observers reported hearing exactly the same sentence in both ears, regardless of one of their ears missing a phoneme.
  
  Section::::Factors.:Language.
   After any PVC there is a pause that can lead to the development of bigeminy. A PVC wavefront often encounters a refractory AV node that does not conduct the wavefront retrograde. Thus the atrium is not depolarized and the sinus node is not reset. Since the sinus p wave to PVC interval is less than the normal P-P interval, the interval between the PVC and the next p wave is prolonged to equal the normal time elapsed during two P-P intervals. This is called a "compensatory" pause. The pause after the PVC leads to a longer recovery time which is associated with a higher likelihood of myocardium being in different stages of repolarization. This then allows for re-entrant circuits and sets up the ventricle for another PVC after the next sinus beat. The constant interval between the sinus beat and PVC suggests a reentrant etiology rather than spontaneous automaticity of the ventricle.
   The active process is also known as the cochlear amplifier. This amplification increases vibrations of the basilar membrane through energy obtained from the Organ of Corti. As the stimulation increases, it is assumed that basilar membrane displacement, caused by the traveling wave, becomes continually more basal in regards to the cochlea. A sustained low-level stimulus can cause an energetic exhaustion of the active system which in turn prevents the passive system from activating.
  
  Section::::Physiology.:Affected mechanisms.:Excessive vibrations.
   Section::::Effects of age and hearing loss on TFS processing.:Psychoacoustical aspects.
   The AHAAH’s improvements in accuracy are often attributed to its sensitivity to the flexing of the middle ear muscle (MEM) and annular ligament of the stapes. When someone is forewarned of a sound, the MEM flexes, which is associated with reduced ability of the sound waves to reverberate. When an impulse sound is produced, the stapes’s annular ligament flexes and strongly clips the sound’s oscillation peak.
   BULLET::::- Plosive versus nasal. If the passage between your mouth and nose is opened by even 1mm during the /b/ closure of "bug," the word becomes "mug." Further opening of the soft palate (2mm, 5mm, even 20mm) has almost no effect on the acoustics; most languages distinguish /b/ from /m/, but few (if any?) distinguish different degrees of soft palate opening.
   The effect reverses in a reverberation room, which echoes real life more so than the typical quiet rooms used for experimentation. This allows for echoes of the spoken phonemes to act as the replacement noise for the missing phonemes. The additional produced white noise that replaces the phoneme adds its own echo and causes listeners to not perform as well.
  
  Section::::Factors.:Rate.
   A full cycle of a sound wave will be described in each example which consists of initial normal conditions (no fluctuations in atmospheric pressure), an increase of air pressure, a subsequent decrease in air pressure which brings it back to normal, a decrease in air pressure (less pressure than initial conditions), and lastly, an increase which brings atmospheric pressure back to normal again. Therefore, the final conditions are the same as the initial, at-rest conditions. 
  