Clinical trial NCT01184248: The Effect of Sound Stimulation on Pure-tone Hearing Threshold
Official title: The Effect of Sound Stimulation on Pure-tone Hearing Threshold
Study type: INTERVENTIONAL
Overall status: COMPLETED
Phase: NA
Conditions: Sensorineural Hearing Loss
Lead sponsor: Earlogic Korea, Inc.
Sponsor class: INDUSTRY
First posted: 2010-08-18
Enrollment: 30
Sex: ALL
Minimum age (years): 18
Maximum age (years): 70
Standard ages: ADULT
OLDER_ADULT
Accepts healthy volunteers: no
Allocation: NON_RANDOMIZED
Intervention model: SINGLE_GROUP
Primary purpose: TREATMENT

Brief summary: The purpose of this study is to investigate if sound stimulation could improve pure-tone hearing threshold.

In the late 1990s, researchers discovered that acoustic stimuli slow progressive sensorineural hearing loss and exposure to a moderately augmented acoustic environment can delay the loss of auditory function. In addition, prolonged exposure to an augmented acoustic environment could improve age-related auditory changes. These ameliorative effects were shown in several types of mouse strains, as long as the acoustic environment was provided prior to the occurrence of severe hearing loss.

In addition to delaying progressive hearing loss, acoustic stimuli could also protect hearing ability against damage by traumatic noise. In particular, a method called forward sound conditioning (i.e., prior exposure to moderate levels of sound) has been shown to reduce noise-induced hearing impairment in a number of mammalian species, including humans.

Interestingly, recent report has suggested that low-level sound conditioning also reduces free radical-induced damage to hair cells, increases antioxidant enzyme activity, and reduces Cox-2 expression in cochlea, and can enhance cochlear sensitivity. Specifically, increased cochlear sensitivity was observed when distortion product otoacoustic emissions (DPOAEs) and compound action potentials (CAPs) were measured.

In addition to forward sound conditioning, backward sound conditioning (i.e., the use of acoustic stimuli after exposure to a traumatic noise) has been shown to protect hearing ability against acoustic trauma and to prevent the cortical map reorganization induced by traumatic noise.

Based on the results of animal studies, the investigators conducted a human study in 2007 and observed that sound stimulation could improve hearing ability. On average, the pure-tone hearing threshold decreased by 8.91 dB after sound stimulation for 2 weeks. In that study, however, the investigators observed only the hearing threshold changes by sound stimulation.

To verify the previous ameliorative effect of sound stimulation, the investigators included a control period in this study.


Eligibility criteria: Inclusion Criteria:

* You are a male or female aged between 18 and 70 years
* You have 25\~70 dB HL hearing loss at any frequency above 1.5 kHz
* You are able to use an mp3 player
* You are able to read English

Exclusion Criteria:

* Under the medications that could cause hearing loss (such as gentamicin, aspirin, ibuprofen, or acetaminophen)
* Chronic disease that could affect hearing (such as diabetes or high blood pressure)
* Temporal hearing loss
* Hearing loss more than 75 dB HL at any frequency
* Ear infections, chronic middle ear disease or any abnormality of the ear canal or ear drum
* Hearing aid user
* Pregnant females

Primary outcomes:
measure: Changes of pure-tone hearing thresholds after sound stimulation
timeFrame: 4-6 weeks
Secondary outcomes:
Other outcomes:
Locations:
city: Los Angeles
country: United States
facility: Earlogic Corporation
state: California
Study officials:
affiliation: Earlogic Auditory Research Institute
name: Eunyee Kwak, Ph.D.
role: PRINCIPAL_INVESTIGATOR
References:
citation: Canlon B, Borg E, Flock A. Protection against noise trauma by pre-exposure to a low level acoustic stimulus. Hear Res. 1988 Jul 15;34(2):197-200. doi: 10.1016/0378-5955(88)90107-4.
citation: Miyakita T, Hellstrom PA, Frimanson E, Axelsson A. Effect of low level acoustic stimulation on temporary threshold shift in young humans. Hear Res. 1992 Jul;60(2):149-55. doi: 10.1016/0378-5955(92)90017-h.
citation: Harris KC, Bielefeld E, Hu BH, Henderson D. Increased resistance to free radical damage induced by low-level sound conditioning. Hear Res. 2006 Mar;213(1-2):118-29. doi: 10.1016/j.heares.2005.11.012. Epub 2006 Feb 8.
citation: Kujawa SG, Liberman MC. Long-term sound conditioning enhances cochlear sensitivity. J Neurophysiol. 1999 Aug;82(2):863-73. doi: 10.1152/jn.1999.82.2.863.
citation: Niu X, Tahera Y, Canlon B. Protection against acoustic trauma by forward and backward sound conditioning. Audiol Neurootol. 2004 Sep-Oct;9(5):265-73. doi: 10.1159/000080226. Epub 2004 Aug 13.
citation: Norena AJ, Eggermont JJ. Enriched acoustic environment after noise trauma reduces hearing loss and prevents cortical map reorganization. J Neurosci. 2005 Jan 19;25(3):699-705. doi: 10.1523/JNEUROSCI.2226-04.2005.