Noise-Induced Hearing Loss
Conditions
Keywords
Noise, Hearing Loss, Tinnitus, Antioxidant, Vasodilator, Beta-Carotene, Vitamin C, Vitamin E, Magnesium
Brief summary
Noise-induced hearing loss (NIHL) is a significant clinical, social, and economic issue. Studies in animals have allowed us to identify mechanisms contributing to NIHL, including direct mechanical trauma, free radicals formed in association with metabolic stress, and reduced blood flow. A combination of antioxidant vitamins (beta-carotene, and vitamins C and E) and the mineral magnesium (which acts in part as a vasodilator but also as an antioxidant) is highly effective in preventing NIHL in animals. These studies evaluate efficacy of this intervention in humans. Hypothesis: Treatment with these micronutrients provides safe, effective attenuation of acute hearing changes induced by exposure to real-world sounds producing temporary (non-permanent) or permanent hearing changes induced by exposure to real-world sounds. Experiment 1: Digital Audio Player studies (University of Florida, Gainesville). Prevention of \*temporary\* elevations in hearing thresholds, induced by exposure to moderately loud music, will be measured. Subjects will be 70 young adults with equal numbers of male and female participants.
Detailed description
This study assessed the potential for prevention of the temporary changes in hearing that can occur after use of a music player device for 4 hours. All participants listened to one of two playlists (pop or rock) set at the same volumes to provide equivalent and consistent exposures across participants. Participants received either a dietary supplement or a placebo once/daily for three days prior to the day of music exposure, and also on the day of music exposure. The fourth and final dose was consumed immediately prior to music listening and consumption was observed by a member of the study team. Changes in hearing were assessed 15-min post-music, and then 1, 2, and 3 hours later, as well as the following day and 1 week later.
Interventions
DRUGbeta-carotene, vitamins C and E, magnesium
6 mint-flavored tablets per day, taken once daily total daily dose label claim: micronutrient combination of 500 mg vitamin C (magnesium ascorbate), 315 mg magnesium (magnesium citrate, magnesium ascorbate, magnesium stearate), 267 mg vitamin E (d-α-tocopherol acetate), and 18 mg beta carotene.
OTHERPlacebo
6 mint-flavored tablets per day, containing inactive substances including mannitol, peppermint flavor, sucralose, color prep, iron oxide yellow synthetic, stearic acid (vegetable grade), and silicon dioxide colloidal.
Sponsors
National Institute on Deafness and Other Communication Disorders (NIDCD)
University of Florida
Southern Illinois University
Hearing Health Science, Inc.
University of Michigan
Study design
Allocation
RANDOMIZED
Intervention model
PARALLEL
Primary purpose
PREVENTION
Masking
QUADRUPLE (Subject, Caregiver, Investigator, Outcomes Assessor)
Eligibility
Sex/Gender
ALL
Age
18 Years to 35 Years
Healthy volunteers
Yes
Inclusion criteria
Hearing inclusion criteria are as follows for all studies: * subjects must have a normal audiologic assessment at baseline consisting of: 1. symmetric hearing with air conduction thresholds no worse than 25 dB HL at tested frequencies between .25 - 8 kHz; 2. no significant threshold asymmetry (i.e., greater than 15 dB) between the ears at any test frequency; 3. no significant air-bone gaps (i.e., greater than 10 dB); and 4. Type A tympanograms bilaterally, defined as a range of -140 to +40 daPa based on the 90% range for adults (Margolis & Hunter 2000). Additional criteria are as follows: * No history of ear disease, able to provide informed consent, agree to follow study procedures, normal health screening at study entry
Exclusion criteria
* Pregnant or trying to become pregnant within study period (females) * subjects belonging to vulnerable populations * subjects with any history of chronic disease * hearing loss that exceeds limits specified above * inability or failure to provide informed consent * medical conditions that require treatment with drugs including anticoagulants * diuretics * digoxin * aspirin/salicylate * barbiturates * minocycline
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Average Threshold Shift at 4 kHz in Both Ears | 15 min, 1 hr intervals for 3 hours to measure temporary changes; additional tests at 1 day and 1 week post-exposure. | The study measures the quietest decibel level the participants can hear before the 4 hour music exposure The first post-music test to measure shift is 15 minutes after the music exposure is completed and again at 1 hour intervals. The shift represents the mean change in quietest decibel volume detected between baseline (pre-music) and post music. |
Secondary
| Measure | Time frame | Description |
|---|---|---|
| Threshold Shift at Individual Frequencies, Including 0.25, 0.5, 1, 2, 3, 6, and 8 kHz, 15 Min Post-music | 15 min | The study measures the quietest decibel level the participants can hear before the 4 hour music exposure The first post-music test to measure shift is 15 minutes after the music exposure is completed and again at 1 hour intervals. The shift represents the mean change in quietest decibel volume detected between baseline (pre-music) and post music. |
| Tinnitus | immediate, repeated measures at 1 hr intervals for 3 hours to measure temporary changes; additional tests at 1 day and 1 week post-exposure. | Presence of tinnitus was assessed using yes/no question. If tinnitus was reported, perception was assessed using survey. |
Other
| Measure | Time frame | Description |
|---|---|---|
| Distortion Product Otoacoustic Emission (DPOAE) Amplitude - f1+3328 HZ, F2+ 3984 Hz; 30 Minutes | 15 min | DPOAE amplitude was measured following the audiometric testing completion at approximately 30 minutes post music. Test time was approximate as DPOAE tests began as soon as threshold testing was completed. F1 and F2 frequency pairs included 3328 and 3984 Hz, F1 sound levels started at 65 dB SPL at each frequency, and decreased in 5 dB steps to a level of 25 dB SPL. F2 levels were 10 dB lower than F1 levels. Threshold tests began precisely at 15 min, 1 hr 15 min, 2 hr 15 min, 3 hr 15 min. Threshold tests take approximately 15 min, but the exact duration of testing varies from subject to subject. The OAE testing began as soon as threshold testing completed. Thus, OAE tests began approx. 30 min, 1 hr 30 min, 2 hr 30 min, and 3 hr 30 min post music, but for some it may have been a little bit earlier or a little bit later (i.e., the test may have begun as early as 25 min or as late as 35 min post music, depending on how quickly the subject completed threshold testing). |
| Distortion Product Otoacoustic Emission (DPOAE) Amplitude - Additional Pairs | 15 minutes | Distortion Product Otoacoustic Emission (DPOAE) Amplitude was measured following the audiometric testing completion at approximately 30 minutes post music. F1 and F2 frequency pairs included 6656 and 8015 Hz, 5016 and 6000 Hz, 2484 and 3000 Hz, and 1687 and 2015 Hz. F1 sound levels started at 65 dB SPL at each frequency, and decreased in 5 dB steps to a level of 25 dB SPL. F2 levels were 10dB lower than F1 Levels. Threshold tests began precisely at 15 min, 1 hr 15 min, 2 hr 15 min, 3 hr 15 min. The OAE testing began as soon as threshold testing completed. Threshold tests take approximately 15 min, but the exact duration of testing varies among subjects. Thus, OAE tests began approx. 30 min, 1 hr 30 min, 2 hr 30 min, and 3 hr 30 min post music, but for some it may have been a little bit earlier than for others (i.e., the test may have begun as early as 25 min or as late as 35 min post music, depending on how quickly the subject completed threshold testing). |
| Threshold Shift at Individual Frequencies, Including 0.25, 0.5, 1, 2, 3, 6, 8, kHz | repeated measures at 1 hr intervals for 3 hours to measure temporary changes; additional tests at 1 day and 1 week post-exposure. | — |
| Distortion Product Otoacoustic Emission (DPOAE) Amplitude - Additional Time Measures | repeated measures at 1 hr intervals for 3 hours to measure temporary changes; additional tests at 1 day and 1 week post-exposure. | DPOAE amplitude was measured following the audiometric testing completion at each of the post-music test times. F1 and F2 frequency pairs included 6656 and 8015 Hz, 5016 and 6000 Hz, 3328 and 3984 Hz, 2484 and 3000 Hz, and 1687 and 2015 Hz. F1 sound levels started at 65 dB SPL at each frequency, and decreased in 5 dB steps to a level of 25 dB SPL. F2 levels were 10 dB lower than F1 levels. |
Countries
United States
Participant flow
Participants by arm
| Arm | Count |
|---|---|
| Nutrients Dietary Supplement. Subjects in University of Florida music player study who are assigned to active agent treatment group. Nutrient tablet treatments are consumed for 4 days.
Dietary supplement consisting of beta-carotene, vitamins C and E, magnesium: 6 mint-flavored tablets per day, taken once daily
total daily dose label claim: micronutrient combination of 500 mg vitamin C (magnesium ascorbate), 315 mg magnesium (magnesium citrate, magnesium ascorbate, magnesium stearate), 267 mg vitamin E (d-α-tocopherol acetate), and 18 mg beta carotene. | 37 |
| Placebo for Nutrients Subjects in University of Florida music player study who are assigned to control (placebo) condition. Placebo tablets are consumed for 4 days.
Placebo Control: 6 mint-flavored tablets per day, containing inactive substances including mannitol, peppermint flavor, sucralose, color prep, iron oxide yellow synthetic, stearic acid (vegetable grade), and silicon dioxide colloidal. | 35 |
| Total | 72 |
Baseline characteristics
| Characteristic | Nutrients | Total | Placebo for Nutrients |
|---|---|---|---|
| Age, Continuous | 22.0 years STANDARD_DEVIATION 2.4 | 21.6 years STANDARD_DEVIATION 2.4 | 21.3 years STANDARD_DEVIATION 2.4 |
| Ethnicity (NIH/OMB) Hispanic or Latino | 10 Participants | 20 Participants | 10 Participants |
| Ethnicity (NIH/OMB) Not Hispanic or Latino | 26 Participants | 51 Participants | 25 Participants |
| Ethnicity (NIH/OMB) Unknown or Not Reported | 1 Participants | 1 Participants | 0 Participants |
| Race (NIH/OMB) American Indian or Alaska Native | 0 Participants | 0 Participants | 0 Participants |
| Race (NIH/OMB) Asian | 4 Participants | 7 Participants | 3 Participants |
| Race (NIH/OMB) Black or African American | 2 Participants | 4 Participants | 2 Participants |
| Race (NIH/OMB) More than one race | 3 Participants | 7 Participants | 4 Participants |
| Race (NIH/OMB) Native Hawaiian or Other Pacific Islander | 0 Participants | 0 Participants | 0 Participants |
| Race (NIH/OMB) Unknown or Not Reported | 3 Participants | 3 Participants | 0 Participants |
| Race (NIH/OMB) White | 25 Participants | 51 Participants | 26 Participants |
| Region of Enrollment United States | 37 participants | 72 participants | 35 participants |
| Sex: Female, Male Female | 17 Participants | 32 Participants | 15 Participants |
| Sex: Female, Male Male | 20 Participants | 40 Participants | 20 Participants |
Adverse events
| Event type | EG000 affected / at risk | EG001 affected / at risk |
|---|---|---|
| deaths Total, all-cause mortality | — / — | — / — |
| other Total, other adverse events | 2 / 37 | 5 / 35 |
| serious Total, serious adverse events | 0 / 37 | 0 / 35 |
Outcome results
Primary
Average Threshold Shift at 4 kHz in Both Ears
The study measures the quietest decibel level the participants can hear before the 4 hour music exposure The first post-music test to measure shift is 15 minutes after the music exposure is completed and again at 1 hour intervals. The shift represents the mean change in quietest decibel volume detected between baseline (pre-music) and post music.
Time frame: 15 min, 1 hr intervals for 3 hours to measure temporary changes; additional tests at 1 day and 1 week post-exposure.
Population: All subjects that completed music exposure were analyzed; two subjects withdrew from study prior to music exposure.
| Arm | Measure | Group | Value (MEAN) | Dispersion |
|---|---|---|---|---|
| Nutrients | Average Threshold Shift at 4 kHz in Both Ears | 15 minutes post exposure | 3.94 decibels | Standard Deviation 4.39 |
| Nutrients | Average Threshold Shift at 4 kHz in Both Ears | 1 hour and 15 minutes after exposure | 2.77 decibels | Standard Deviation 4 |
| Nutrients | Average Threshold Shift at 4 kHz in Both Ears | 2 hours and 15 minutes after exposure | 2.27 decibels | Standard Deviation 3.81 |
| Nutrients | Average Threshold Shift at 4 kHz in Both Ears | 3 hours and 15 minutes after exposure | 1.51 decibels | Standard Deviation 3.18 |
| Nutrients | Average Threshold Shift at 4 kHz in Both Ears | 1 day after exposure | .09 decibels | Standard Deviation 1.91 |
| Nutrients | Average Threshold Shift at 4 kHz in Both Ears | 1 week after exposure | -.57 decibels | Standard Deviation 2.25 |
| Placebo for Nutrients | Average Threshold Shift at 4 kHz in Both Ears | 1 day after exposure | .00 decibels | Standard Deviation 1.91 |
| Placebo for Nutrients | Average Threshold Shift at 4 kHz in Both Ears | 15 minutes post exposure | 3.4 decibels | Standard Deviation 3.81 |
| Placebo for Nutrients | Average Threshold Shift at 4 kHz in Both Ears | 3 hours and 15 minutes after exposure | .88 decibels | Standard Deviation 2.48 |
| Placebo for Nutrients | Average Threshold Shift at 4 kHz in Both Ears | 1 hour and 15 minutes after exposure | 2.03 decibels | Standard Deviation 3.12 |
| Placebo for Nutrients | Average Threshold Shift at 4 kHz in Both Ears | 1 week after exposure | .11 decibels | Standard Deviation 2.25 |
| Placebo for Nutrients | Average Threshold Shift at 4 kHz in Both Ears | 2 hours and 15 minutes after exposure | 2.03 decibels | Standard Deviation 3.12 |
Comparison: 15 minutes after exposurep-value: 0.58t-test, 2 sided
Comparison: 1 hour and 15 minutes after exposurep-value: 0.39t-test, 2 sided
Comparison: 2 Hours 15 minutes after exposurep-value: 0.51t-test, 2 sided
Comparison: 3 hours, 15 minutes after exposurep-value: 0.36t-test, 2 sided
Comparison: 1 day after exposurep-value: 0.86t-test, 2 sided
Comparison: 1 week after exposurep-value: 0.24t-test, 2 sided
Secondary
Threshold Shift at Individual Frequencies, Including 0.25, 0.5, 1, 2, 3, 6, and 8 kHz, 15 Min Post-music
The study measures the quietest decibel level the participants can hear before the 4 hour music exposure The first post-music test to measure shift is 15 minutes after the music exposure is completed and again at 1 hour intervals. The shift represents the mean change in quietest decibel volume detected between baseline (pre-music) and post music.
Time frame: 15 min
Population: all participants that completed music exposure were assessed; two participants withdrew prior to music exposure.
| Arm | Measure | Group | Value (MEAN) | Dispersion |
|---|---|---|---|---|
| Nutrients | Threshold Shift at Individual Frequencies, Including 0.25, 0.5, 1, 2, 3, 6, and 8 kHz, 15 Min Post-music | 1000 Hz | 1.6571 decibels | Standard Deviation 0.4119 |
| Nutrients | Threshold Shift at Individual Frequencies, Including 0.25, 0.5, 1, 2, 3, 6, and 8 kHz, 15 Min Post-music | 3000 Hz | 3.0286 decibels | Standard Deviation 0.7944 |
| Nutrients | Threshold Shift at Individual Frequencies, Including 0.25, 0.5, 1, 2, 3, 6, and 8 kHz, 15 Min Post-music | 500 Hz | 0.8 decibels | Standard Deviation 0.4177 |
| Nutrients | Threshold Shift at Individual Frequencies, Including 0.25, 0.5, 1, 2, 3, 6, and 8 kHz, 15 Min Post-music | 6000 Hz | 2.2286 decibels | Standard Deviation 0.4203 |
| Nutrients | Threshold Shift at Individual Frequencies, Including 0.25, 0.5, 1, 2, 3, 6, and 8 kHz, 15 Min Post-music | 2000 Hz | 1.9429 decibels | Standard Deviation 0.6403 |
| Nutrients | Threshold Shift at Individual Frequencies, Including 0.25, 0.5, 1, 2, 3, 6, and 8 kHz, 15 Min Post-music | 8000 Hz | 0.6286 decibels | Standard Deviation 0.4474 |
| Nutrients | Threshold Shift at Individual Frequencies, Including 0.25, 0.5, 1, 2, 3, 6, and 8 kHz, 15 Min Post-music | 250 Hz | 0.2571 decibels | Standard Deviation 0.3487 |
| Placebo for Nutrients | Threshold Shift at Individual Frequencies, Including 0.25, 0.5, 1, 2, 3, 6, and 8 kHz, 15 Min Post-music | 8000 Hz | 1.0000 decibels | Standard Deviation 0.5266 |
| Placebo for Nutrients | Threshold Shift at Individual Frequencies, Including 0.25, 0.5, 1, 2, 3, 6, and 8 kHz, 15 Min Post-music | 250 Hz | 1.2286 decibels | Standard Deviation 0.4921 |
| Placebo for Nutrients | Threshold Shift at Individual Frequencies, Including 0.25, 0.5, 1, 2, 3, 6, and 8 kHz, 15 Min Post-music | 500 Hz | 1.0000 decibels | Standard Deviation 0.3932 |
| Placebo for Nutrients | Threshold Shift at Individual Frequencies, Including 0.25, 0.5, 1, 2, 3, 6, and 8 kHz, 15 Min Post-music | 1000 Hz | 1.6857 decibels | Standard Deviation 0.4505 |
| Placebo for Nutrients | Threshold Shift at Individual Frequencies, Including 0.25, 0.5, 1, 2, 3, 6, and 8 kHz, 15 Min Post-music | 2000 Hz | 1.9143 decibels | Standard Deviation 0.4365 |
| Placebo for Nutrients | Threshold Shift at Individual Frequencies, Including 0.25, 0.5, 1, 2, 3, 6, and 8 kHz, 15 Min Post-music | 3000 Hz | 2.7714 decibels | Standard Deviation 0.5219 |
| Placebo for Nutrients | Threshold Shift at Individual Frequencies, Including 0.25, 0.5, 1, 2, 3, 6, and 8 kHz, 15 Min Post-music | 6000 Hz | 2.1143 decibels | Standard Deviation 0.4579 |
Secondary
Tinnitus
Presence of tinnitus was assessed using yes/no question. If tinnitus was reported, perception was assessed using survey.
Time frame: immediate, repeated measures at 1 hr intervals for 3 hours to measure temporary changes; additional tests at 1 day and 1 week post-exposure.
Population: all participants completing music exposure completed tinnitus surveys.
| Arm | Measure | Value (NUMBER) |
|---|---|---|
| Nutrients | Tinnitus | 11 participants |
| Placebo for Nutrients | Tinnitus | 6 participants |
Other Pre-specified
Distortion Product Otoacoustic Emission (DPOAE) Amplitude - Additional Pairs
Distortion Product Otoacoustic Emission (DPOAE) Amplitude was measured following the audiometric testing completion at approximately 30 minutes post music. F1 and F2 frequency pairs included 6656 and 8015 Hz, 5016 and 6000 Hz, 2484 and 3000 Hz, and 1687 and 2015 Hz. F1 sound levels started at 65 dB SPL at each frequency, and decreased in 5 dB steps to a level of 25 dB SPL. F2 levels were 10dB lower than F1 Levels. Threshold tests began precisely at 15 min, 1 hr 15 min, 2 hr 15 min, 3 hr 15 min. The OAE testing began as soon as threshold testing completed. Threshold tests take approximately 15 min, but the exact duration of testing varies among subjects. Thus, OAE tests began approx. 30 min, 1 hr 30 min, 2 hr 30 min, and 3 hr 30 min post music, but for some it may have been a little bit earlier than for others (i.e., the test may have begun as early as 25 min or as late as 35 min post music, depending on how quickly the subject completed threshold testing).
Time frame: 15 minutes
Other Pre-specified
Distortion Product Otoacoustic Emission (DPOAE) Amplitude - Additional Time Measures
DPOAE amplitude was measured following the audiometric testing completion at each of the post-music test times. F1 and F2 frequency pairs included 6656 and 8015 Hz, 5016 and 6000 Hz, 3328 and 3984 Hz, 2484 and 3000 Hz, and 1687 and 2015 Hz. F1 sound levels started at 65 dB SPL at each frequency, and decreased in 5 dB steps to a level of 25 dB SPL. F2 levels were 10 dB lower than F1 levels.
Time frame: repeated measures at 1 hr intervals for 3 hours to measure temporary changes; additional tests at 1 day and 1 week post-exposure.
Other Pre-specified
Distortion Product Otoacoustic Emission (DPOAE) Amplitude - f1+3328 HZ, F2+ 3984 Hz; 30 Minutes
DPOAE amplitude was measured following the audiometric testing completion at approximately 30 minutes post music. Test time was approximate as DPOAE tests began as soon as threshold testing was completed. F1 and F2 frequency pairs included 3328 and 3984 Hz, F1 sound levels started at 65 dB SPL at each frequency, and decreased in 5 dB steps to a level of 25 dB SPL. F2 levels were 10 dB lower than F1 levels. Threshold tests began precisely at 15 min, 1 hr 15 min, 2 hr 15 min, 3 hr 15 min. Threshold tests take approximately 15 min, but the exact duration of testing varies from subject to subject. The OAE testing began as soon as threshold testing completed. Thus, OAE tests began approx. 30 min, 1 hr 30 min, 2 hr 30 min, and 3 hr 30 min post music, but for some it may have been a little bit earlier or a little bit later (i.e., the test may have begun as early as 25 min or as late as 35 min post music, depending on how quickly the subject completed threshold testing).
Time frame: 15 min
Population: Data for one participant in the placebo group is incomplete.
| Arm | Measure | Group | Value (MEAN) | Dispersion |
|---|---|---|---|---|
| Nutrients | Distortion Product Otoacoustic Emission (DPOAE) Amplitude - f1+3328 HZ, F2+ 3984 Hz; 30 Minutes | f2=3984Hz,f1=55dB,left | -2.7 decibels (dB) | Standard Deviation 6.8 |
| Nutrients | Distortion Product Otoacoustic Emission (DPOAE) Amplitude - f1+3328 HZ, F2+ 3984 Hz; 30 Minutes | f2=3984Hz,f1=65dB,right | 3.9 decibels (dB) | Standard Deviation 9.3 |
| Nutrients | Distortion Product Otoacoustic Emission (DPOAE) Amplitude - f1+3328 HZ, F2+ 3984 Hz; 30 Minutes | f2=3984Hz,f1=60dB,right | 0.9 decibels (dB) | Standard Deviation 8.9 |
| Nutrients | Distortion Product Otoacoustic Emission (DPOAE) Amplitude - f1+3328 HZ, F2+ 3984 Hz; 30 Minutes | f2=3984Hz,f1=55dB,right | -3.3 decibels (dB) | Standard Deviation 8.8 |
| Nutrients | Distortion Product Otoacoustic Emission (DPOAE) Amplitude - f1+3328 HZ, F2+ 3984 Hz; 30 Minutes | f2=3984Hz,f1=50dB,right | -7.8 decibels (dB) | Standard Deviation 9.6 |
| Nutrients | Distortion Product Otoacoustic Emission (DPOAE) Amplitude - f1+3328 HZ, F2+ 3984 Hz; 30 Minutes | f2=3984Hz,f1=45dB,right | -13.9 decibels (dB) | Standard Deviation 9.8 |
| Nutrients | Distortion Product Otoacoustic Emission (DPOAE) Amplitude - f1+3328 HZ, F2+ 3984 Hz; 30 Minutes | f2=3984Hz,f1=40dB,right | -19.7 decibels (dB) | Standard Deviation 12.8 |
| Nutrients | Distortion Product Otoacoustic Emission (DPOAE) Amplitude - f1+3328 HZ, F2+ 3984 Hz; 30 Minutes | f2=3984Hz,f1=35dB,right | -23.8 decibels (dB) | Standard Deviation 8.3 |
| Nutrients | Distortion Product Otoacoustic Emission (DPOAE) Amplitude - f1+3328 HZ, F2+ 3984 Hz; 30 Minutes | f2=3984Hz,f1=30dB,right | -25.5 decibels (dB) | Standard Deviation 10.2 |
| Nutrients | Distortion Product Otoacoustic Emission (DPOAE) Amplitude - f1+3328 HZ, F2+ 3984 Hz; 30 Minutes | f2=3984Hz,f1=25dB,right | -26.4 decibels (dB) | Standard Deviation 10.6 |
| Nutrients | Distortion Product Otoacoustic Emission (DPOAE) Amplitude - f1+3328 HZ, F2+ 3984 Hz; 30 Minutes | f2=3984Hz,f1=65dB,left | 4.4 decibels (dB) | Standard Deviation 8.1 |
| Nutrients | Distortion Product Otoacoustic Emission (DPOAE) Amplitude - f1+3328 HZ, F2+ 3984 Hz; 30 Minutes | f2=3984Hz,f1=60dB,left | 1.8 decibels (dB) | Standard Deviation 6.5 |
| Nutrients | Distortion Product Otoacoustic Emission (DPOAE) Amplitude - f1+3328 HZ, F2+ 3984 Hz; 30 Minutes | f2=3984Hz,f1=50dB,left | -7.0 decibels (dB) | Standard Deviation 7.3 |
| Nutrients | Distortion Product Otoacoustic Emission (DPOAE) Amplitude - f1+3328 HZ, F2+ 3984 Hz; 30 Minutes | f2=3984Hz,f1=45dB,left | -13.6 decibels (dB) | Standard Deviation 7.6 |
| Nutrients | Distortion Product Otoacoustic Emission (DPOAE) Amplitude - f1+3328 HZ, F2+ 3984 Hz; 30 Minutes | f2=3984Hz,f1=40dB,left | -18.6 decibels (dB) | Standard Deviation 8.7 |
| Nutrients | Distortion Product Otoacoustic Emission (DPOAE) Amplitude - f1+3328 HZ, F2+ 3984 Hz; 30 Minutes | f2=3984Hz,f1=35dB,left | -22.1 decibels (dB) | Standard Deviation 12.8 |
| Nutrients | Distortion Product Otoacoustic Emission (DPOAE) Amplitude - f1+3328 HZ, F2+ 3984 Hz; 30 Minutes | f2=3984Hz,f1=30dB,left | -30.9 decibels (dB) | Standard Deviation 8.2 |
| Nutrients | Distortion Product Otoacoustic Emission (DPOAE) Amplitude - f1+3328 HZ, F2+ 3984 Hz; 30 Minutes | f2=3984Hz,f1=25dB,left | -32.2 decibels (dB) | Standard Deviation 7.7 |
| Placebo for Nutrients | Distortion Product Otoacoustic Emission (DPOAE) Amplitude - f1+3328 HZ, F2+ 3984 Hz; 30 Minutes | f2=3984Hz,f1=45dB,left | -12.2 decibels (dB) | Standard Deviation 10.2 |
| Placebo for Nutrients | Distortion Product Otoacoustic Emission (DPOAE) Amplitude - f1+3328 HZ, F2+ 3984 Hz; 30 Minutes | f2=3984Hz,f1=55dB,left | -1.3 decibels (dB) | Standard Deviation 7.6 |
| Placebo for Nutrients | Distortion Product Otoacoustic Emission (DPOAE) Amplitude - f1+3328 HZ, F2+ 3984 Hz; 30 Minutes | f2=3984Hz,f1=25dB,right | -28.0 decibels (dB) | Standard Deviation 11.1 |
| Placebo for Nutrients | Distortion Product Otoacoustic Emission (DPOAE) Amplitude - f1+3328 HZ, F2+ 3984 Hz; 30 Minutes | f2=3984Hz,f1=65dB,right | 6.6 decibels (dB) | Standard Deviation 6.5 |
| Placebo for Nutrients | Distortion Product Otoacoustic Emission (DPOAE) Amplitude - f1+3328 HZ, F2+ 3984 Hz; 30 Minutes | f2=3984Hz,f1=25dB,left | -29.8 decibels (dB) | Standard Deviation 8.2 |
| Placebo for Nutrients | Distortion Product Otoacoustic Emission (DPOAE) Amplitude - f1+3328 HZ, F2+ 3984 Hz; 30 Minutes | f2=3984Hz,f1=60dB,right | 5.1 decibels (dB) | Standard Deviation 4.6 |
| Placebo for Nutrients | Distortion Product Otoacoustic Emission (DPOAE) Amplitude - f1+3328 HZ, F2+ 3984 Hz; 30 Minutes | f2=3984Hz,f1=65dB,left | 4.3 decibels (dB) | Standard Deviation 10.1 |
| Placebo for Nutrients | Distortion Product Otoacoustic Emission (DPOAE) Amplitude - f1+3328 HZ, F2+ 3984 Hz; 30 Minutes | f2=3984Hz,f1=55dB,right | 0.5 decibels (dB) | Standard Deviation 6 |
| Placebo for Nutrients | Distortion Product Otoacoustic Emission (DPOAE) Amplitude - f1+3328 HZ, F2+ 3984 Hz; 30 Minutes | f2=3984Hz,f1=40dB,left | -19.2 decibels (dB) | Standard Deviation 10.1 |
| Placebo for Nutrients | Distortion Product Otoacoustic Emission (DPOAE) Amplitude - f1+3328 HZ, F2+ 3984 Hz; 30 Minutes | f2=3984Hz,f1=50dB,right | -4.2 decibels (dB) | Standard Deviation 7 |
| Placebo for Nutrients | Distortion Product Otoacoustic Emission (DPOAE) Amplitude - f1+3328 HZ, F2+ 3984 Hz; 30 Minutes | f2=3984Hz,f1=60dB,left | 1.3 decibels (dB) | Standard Deviation 8.5 |
| Placebo for Nutrients | Distortion Product Otoacoustic Emission (DPOAE) Amplitude - f1+3328 HZ, F2+ 3984 Hz; 30 Minutes | f2=3984Hz,f1=45dB,right | -10.4 decibels (dB) | Standard Deviation 7.7 |
| Placebo for Nutrients | Distortion Product Otoacoustic Emission (DPOAE) Amplitude - f1+3328 HZ, F2+ 3984 Hz; 30 Minutes | f2=3984Hz,f1=30dB,left | -27.1 decibels (dB) | Standard Deviation 9 |
| Placebo for Nutrients | Distortion Product Otoacoustic Emission (DPOAE) Amplitude - f1+3328 HZ, F2+ 3984 Hz; 30 Minutes | f2=3984Hz,f1=40dB,right | -15.6 decibels (dB) | Standard Deviation 8.6 |
| Placebo for Nutrients | Distortion Product Otoacoustic Emission (DPOAE) Amplitude - f1+3328 HZ, F2+ 3984 Hz; 30 Minutes | f2=3984Hz,f1=50dB,left | -7.7 decibels (dB) | Standard Deviation 9.6 |
| Placebo for Nutrients | Distortion Product Otoacoustic Emission (DPOAE) Amplitude - f1+3328 HZ, F2+ 3984 Hz; 30 Minutes | f2=3984Hz,f1=35dB,right | -21.1 decibels (dB) | Standard Deviation 9.6 |
| Placebo for Nutrients | Distortion Product Otoacoustic Emission (DPOAE) Amplitude - f1+3328 HZ, F2+ 3984 Hz; 30 Minutes | f2=3984Hz,f1=35dB,left | -23.6 decibels (dB) | Standard Deviation 8.8 |
| Placebo for Nutrients | Distortion Product Otoacoustic Emission (DPOAE) Amplitude - f1+3328 HZ, F2+ 3984 Hz; 30 Minutes | f2=3984Hz,f1=30dB,right | -26.8 decibels (dB) | Standard Deviation 9.7 |
Other Pre-specified
Threshold Shift at Individual Frequencies, Including 0.25, 0.5, 1, 2, 3, 6, 8, kHz
Time frame: repeated measures at 1 hr intervals for 3 hours to measure temporary changes; additional tests at 1 day and 1 week post-exposure.