The Effect of Sound Stimulation on Pure-tone Hearing Threshold

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.

Study Overview

• Status: Completed
• Conditions: Sensorineural Hearing Loss
• Intervention / Treatment: Behavioral: Sound stimulation

• Study Type: Interventional
• Enrollment (Anticipated): 30
• Phase: Not Applicable

Contacts and Locations

Study Locations

• United States
  • California
    • Los Angeles, California, United States, 90005
      • Earlogic Corporation

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 16 years to 68 years (Adult, Older Adult)
• Accepts Healthy Volunteers: No
• Genders Eligible for Study: All

Description

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

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: Non-Randomized
• Interventional Model: Single Group Assignment
• Masking: None (Open Label)

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Time Frame
Changes of pure-tone hearing thresholds after sound stimulation	4-6 weeks

Collaborators and Investigators

• Sponsor: Earlogic Korea, Inc.
• Investigators: Principal Investigator: Eunyee Kwak, Ph.D., Earlogic Auditory Research Institute

Publications and helpful links

General Publications

• 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.
• 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.
• 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.
• 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.
• 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.
• 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.

Study record dates

Study Major Dates

• Study Start: May 1, 2010
• Primary Completion (Actual): December 1, 2010
• Study Completion (Actual): January 1, 2011

Study Registration Dates

• First Submitted: August 16, 2010
• First Submitted That Met QC Criteria: August 17, 2010
• First Posted (Estimate): August 18, 2010

Study Record Updates

• Last Update Posted (Estimate): September 8, 2011
• Last Update Submitted That Met QC Criteria: September 7, 2011
• Last Verified: September 1, 2011

More Information

Terms related to this study

• Additional Relevant MeSH Terms: Nervous System Diseases; Neurologic Manifestations; Otorhinolaryngologic Diseases; Ear Diseases; Sensation Disorders; Hearing Disorders; Hearing Loss; Hearing Loss, Sensorineural
• Other Study ID Numbers: IEK14152010