Responses of auditory-cortex neurons to structural features of natural sounds


Sound-processing strategies that use the highly non-random structure of natural sounds may confer evolutionary advantage to many species. Auditory processing of natural sounds has been studied almost exclusively in the context of species-specific vocalizations1,2,3,4, although these form only a small part of the acoustic biotope5. To study the relationships between properties of natural soundscapes and neuronal processing mechanisms in the auditory system, we analysed sound from a range of different environments. Here we show that for many non-animal sounds and background mixtures of animal sounds, energy in different frequency bands is coherently modulated. Co-modulation of different frequency bands in background noise facilitates the detection of tones in noise by humans, a phenomenon known as co-modulation masking release (CMR)6,7. We show that co-modulation also improves the ability of auditory-cortex neurons to detect tones in noise, and we propose that this property of auditory neurons may underlie behavioural CMR. This correspondence may represent an adaptation of the auditory system for the use of an attribute of natural sounds to facilitate real-world processing tasks.

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Figure 1: An example of the separation of a sound into a separable spectrogram and a carrier.
Figure 2: Statistics of soundscapes.
Figure 3: Responses to noise alone and to tone plus noise.
Figure 4: Additional examples of CMR.


  1. 1

    Pelleg-Toiba, R. & Wollberg, Z. Discrimination of communication calls in the squirrel monkey: “Call detectors” or “cell ensembles”? J. Basic Clin. Physiol. Pharmacol. 2, 257–272 (1991).

    CAS  Article  Google Scholar 

  2. 2

    Steinschneider, M., Arezzo, J. C. & Vaughan, H. G. J Tonotopic features of speech-evoked activity in primate auditory cortex. Brain Res. 519, 158–168 (1990).

    CAS  Article  Google Scholar 

  3. 3

    Wang, X., Merzenich, M. M., Beitel, R. & Schreiner, C. E. Representation of a species-specific vocalization in the primary auditory cortex of the common marmoset: temporal and spectral characteristics. J. Neurophysiol. 74, 2685–2706 (1995).

    CAS  Article  Google Scholar 

  4. 4

    Suga, N. Philosophy and stimulus design for neuroethology of complex-sound processing. Phil. Trans. R. Soc. Lond. B 336, 423–428 (1992).

    ADS  CAS  Article  Google Scholar 

  5. 5

    Aertsen, A. M. H. J., Smolders, J. W. T. & Johannesma, P. I. M. Neural representation of the acoustic biotope: on the existence of stimulus-event relations for sensory neurons. Biol. Cybern. 32, 175–185 (1979).

    CAS  Article  Google Scholar 

  6. 6

    Hall, J. W., Haggard, M. P. & Fernandes, M. A. Detection in noise by spectro-temporal pattern analysis. J. Acoust. Soc. Am. 76, 50–56 (1984).

    ADS  CAS  Article  Google Scholar 

  7. 7

    Schooneveldt, G. P. & Moore, B. C. Comodulation masking release (CMR) as a function of masker bandwidth, modulator bandwidth, and signal duration. J. Acoust. Soc. Am. 85, 273–281 (1989).

    ADS  CAS  Article  Google Scholar 

  8. 8

    Ruderman, D. L. & Bialek, W. Statistics of natural images: scaling in the woods. Phys. Rev. Lett. 73, 814–817 (1994).

    ADS  CAS  Article  Google Scholar 

  9. 9

    Richards, D. G. & Wiley, R. H. Reverberations and amplitude fluctuations in the propagation of sound in a forest: implication for animal communication. Am. Nat. 115, 381–399 (1980).

    Article  Google Scholar 

  10. 10

    Klump, G. M. & Langemann, U. Comodulation masking release in a songbird. Hearing Res. 87, 157–164 (1995).

    CAS  Article  Google Scholar 

  11. 11

    Rhode, W. S. & Greenwood, D. in Abstracts of the 18th Association for Research in Otolaryngology Meeting 127 (St Petersburg Beach, Florida, (1995)).

    Google Scholar 

  12. 12

    Schreiner, C. E. & Urbas, J. V. Representation of amplitude modulation in the auditory cortex of the cat. II. Comparison between cortical fields. Hearing Res. 32, 49–63 (1988).

    CAS  Article  Google Scholar 

  13. 13

    Rauschecker, J. P., Tian, B. & Hauser, M. Processing of complex sounds in the macaque nonprimary auditory cortex. Science 268, 111–114 (1995).

    ADS  CAS  Article  Google Scholar 

  14. 14

    Eggermont, J. J. Temporal modulation transfer functions for AM and FM stimuli in cat auditory cortex. Effects of carrier type, modulating waveform and intensity. Hearing Res. 74, 51–66 (1994).

    CAS  Article  Google Scholar 

  15. 15

    Carlyon, R. P., Buus, S. & Florentine, M. Comodulation masking release for three types of modulator as a function of modulation rate. Hearing Res. 42, 37–45 (1989).

    CAS  Article  Google Scholar 

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This work was supported by a grant administered by the Israel Science Foundation. We thank E. Vaadia, M. Abeles, E. Young and A. Aertsen for critical comments to this manuscript.

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Correspondence to Israel Nelken.

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Nelken, I., Rotman, Y. & Yosef, O. Responses of auditory-cortex neurons to structural features of natural sounds. Nature 397, 154–157 (1999).

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