Research Article

Threshold of octave masking as a tool to explain cochlear nonlinearity


Background and Aim: The threshold of octave masking test has been used to assess the growth rate of aural harmonics, the intercept point helped differentiate between normal-hearing individuals and sensorineural hearing loss due to noise exposure. With fewer literatures that have been documented, there is a need to explore this test procedure, and hence the purpose of this research is to evaluate the utility of the threshold of octave masking (TOM) procedure in understanding the frequency selectivity and non-linear function of cochlea.
Methods: A total of 10 adults (20 ears) were con­sidered for the test. The TOM test procedure was performed on the subjects where the subjects had to identify the presence of a maskee tone (1 kHz) in the presence of a masker tone (500 Hz) across 5 dB increment of masker tone until the subjects uncomfortable level. A line graph was drawn, extrapolated to identify the point of intercept, which is the threshold of octave masking.
Results: Results reveal that 17 ears did not have a linear growth but had a 10 to 20 dB gap after a particular maskee level. The intercept point of the initial two extreme points was relatively more than the intercept point of the extreme points at higher intensities.
Conclusion: Results from the present study have thrown light on the fact that TOM can be used as a test to measure the frequency selectivity along with the tests of psychophysical tuning curves, notched noise method, non-simultaneous masking, and other non-peripheral masking phenomena.

1. Cortese M, Papal S, Pisciottano F, Elgoyhen AB, Hardelin JP, Petit C, et al. Spectrin βV adaptive mutations and changes in subcellular location correlate with emergence of hair cell electromotility in mammalians. Proc Natl Acad Sci U S A. 2017;114(8):2054-9. doi: 10.1073/pnas.1618778114
2. Bennetto L, Keith JM, Allen PD, Luebke AE. Children with autism spectrum disorder have reduced otoacoustic emissions at the 1 kHz mid-frequency region. Autism Res. 2017;10(2):337-45. doi: 10.1002/aur.1663
3. Thakur JS, Chauhan I, Mohindroo NK, Sharma DR, Azad RK, Vasanthalakshmi MS. Otoacoustic emissions in otitis media with effusion: do they carry any clinical significance? Indian J Otolaryngol Head Neck Surg. 2013;65(1):29-33. doi: 10.1007/s12070-012-0587-5
4. Preyer S, Gummer AW. Nonlinearity of mechanoelectrical transduction of outer hair cells as the source of nonlinear basilar-membrane motion and loudness recruitment. Audiol Neurootol. 1996;1(1):3-11. doi: 10.1159/000259185
5. Moore BCJ, Alcántara JI. The use of psychophysical tuning curves to explore dead regions in the cochlea. Ear Hear. 2001;22(4):268-78. doi: 10.1097/00003446-200108000-00002
6. Thornton AR, Abbas PJ. Low-frequency hearing loss: perception of filtered speech, psychophysical tuning curves, and masking. J Acoust Soc Am. 1980;67(2):638-43. doi: 10.1121/1.383888
7. Wegel RL, Lane CE. The auditory masking of one pure tone by another and its probable relation to the dynamics of the inner ear. Phys Rev. 1924;23(2):266-85. doi: 10.1103/PhysRev.23.266
8. Yantis PA. The aural-harmonic test. Int J Audiol. 1962;1(2):250-3. doi: 10.3109/05384916209074057
9. Alvord LS. Cochlear dysfunction in "normal-hearing" patients with history of noise exposure. Ear Hear. 1983;4(5):247-50. doi: 10.1097/00003446-198309000-00005
10. Clack TD, Bess FH. Aural harmonics: the tone-on-tone masking vs. the best-beat method in normal and abnormal listeners. Acta Otolaryngol. 1969;67(4):399-412. doi: 10.3109/00016486909125466
11. Grimm DM, Bess FH. The threshold of octave masking (TOM) test. Further observations. Acta Otolaryngol. 1973;76(6):419-25. doi: 10.3109/00016487309121530
12. Nelson DA, Bilger RC. Pure-tone octave masking in listeners with sensorineural hearing loss. J Speech Hear Res. 1974;17(2):252-69. doi: 10.1044/jshr.1702.252
13. Chermak GD, Dengerink JE, Dengerink HA. Threshold of octave masking as a predictor of temporary threshold shift following repeated noise exposure. J Speech Hear Disord. 1984;49(3):303-8. doi: 10.1044/jshd.4903.303
14. Humes LE, Schwartz DM, Bess FH. The threshold of octave masking (TOM) test as a predictor of susceptibility to noise-induced hearing loss. J Aud Res. 1977;17(1):5-12.
15. Davis H. An active process in cochlear mechanics. Hear Res. 1983;9(1):79-90. doi: 10.1016/0378-5955(83)90136-3
16. Nelson DA, Fortune TW. High-level psychophysical tuning curves: simultaneous masking by pure tones and 100-Hz-wide noise bands. J Speech Hear Res. 1991;34(2):360-73.
17. Glasberg BR, Moore BCJ. Derivation of auditory filter shapes from notched-noise data. Hear Res. 1990;47(1-2):103-38. doi: 10.1016/0378-5955(90)90170-t
18. Duifhuis H. Consequences of peripheral frequency selectivity for nonsimultaneous masking. J Acoust Soc Am. 1973;54(6):1471-88. doi: 10.1121/1.1914446
19. Zwislocki JJ, Buining E, Glantz J. Frequency distribution of central masking. J Acoust Soc Am. 1968;43(6):1267-71. doi: 10.1121/1.1910978
20. Leek MR, Brown ME, Dorman MF. Informational mas¬king and auditory attention. Percept Psychophys. 1991;50(3):205-14. doi: 10.3758/bf03206743
21. Strickland EA. The relationship between frequency selectivity and overshoot. J Acoust Soc Am. 2001;109(5 Pt 1):2062-73. doi: 10.1121/1.1357811
22. Verhey JL, Pressnitzer D, Winter IM. The psychophysics and physiology of comodulation masking release. Exp Brain Res. 2003;153(4):405-17. doi: 10.1007/s00221-003-1607-1
IssueVol 30 No 1 (2021) QRcode
SectionResearch Article(s)
Threshold of octave masking active mechanism passive mechanism nonlinearity frequency selectivity psychophysical tuning curves

Rights and permissions
Creative Commons License This work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License.
How to Cite
Umashankar A, Ranganathan L, Chandrasekaran P, Prabhu P. Threshold of octave masking as a tool to explain cochlear nonlinearity. Aud Vestib Res. 2021;30(1):24-32.