56. Ahlfors SP, Han J, Lin FH, Witzel T, Belliveau JW, et al. (2010) Cancellation of EEG and MEG signals generated by extended and distributed sources. Hum Brain Mapp 31: 140–149. 57. Na¨a¨ta¨nen R, Picton T (1987) The N1 wave of the human electric and magnetic response to sound: a review and an analysis of the component structure. Psychophysiology 24: 375–425. 58. Hari R, Pelizzone M, Ma¨kela¨ JP, Ha¨llstro¨m J, Leinonen L, et al. (1987) Neuromagnetic responses of the human auditory cortex to on- and offsets of noise bursts. Audiology 26: 31–43. 59. Krumbholz K, Patterson RD, Seither-Preisler A, Lammertmann C, Lu¨tkenh- o¨ner B (2003) Neuromagnetic evidence for a pitch processing center in Heschl’s gyrus. Cereb Cortex 13: 765–772. 60. Ma¨kinen V, May P, Tiitinen H (2004) Transient brain responses predict the temporal dynamics of sound detection in humans. NeuroImage 21: 701–706. 61. Woods DL, Alain C (2001) Conjoining three auditory features: An event-related brain potential study. J Cogn Neurosci 13: 492–509. 62. Pantev C, Okamoto H, Ross B, Stoll W, Ciurlia-Guy E, et al. (2004) Lateral inhibition and habituation of the human auditory cortex. Eur J Neurosci 19: 2337–2344. 63. Atiani S, Elhilali M, David SV, Fritz JB, Shamma SA (2009) Task difficulty and performance induce diverse adaptive patterns in gain and shape of primary auditory cortical receptive fields. Neuron 61: 467–480. Two-Stage Processing of Sounds during Attention 64. Fritz J, Shamma S, Elhilali M, Klein D (2003) Rapid task-related plasticity of spectrotemporal receptive fields in primary auditory cortex. Nat Neurosci 6: 1216–1223. 65. Fritz JB, Elhilali M, Shamma SA (2005) Differential dynamic plasticity of A1 receptive fields during multiple spectral tasks. J Neurosci 25: 7623–7635. 66. Glasberg BR, Moore BCJ (1990) Derivation of auditory filter shapes from notched-noise data. Hear Res 47: 103–138. 67. Zwicker E, Terhardt E (1980) Analytical expressions for critical-band rate and critical bandwidth as a function of frequency. J Acoust Soc Am 68: 1523–1525. 68. Soeta Y, Nakagawa S (2006) Complex tone processing and critical band in the human auditory cortex. Hear Res 222: 125–132. 69. Soeta Y, Nakagawa S, Matsuoka K (2005) Effects of the critical band on auditory-evoked magnetic fields. NeuroReport 16: 1787–1790. 70. Sams M, Salmelin R (1994) Evidence of sharp frequency tuning in the human auditory cortex. Hear Res 75: 67–74. 71. Paltoglou AE, Sumner CJ, Hall DA (2009) Examining the role of frequency specificity in the enhancement and suppression of human cortical activity by auditory selective attention. Hear Res 257: 106–118. 72. Fletcher H (1940) Auditory patterns. Rev Mod Phys 12: 47–65. 73. Levitt H (1971) Transformed up-down methods in psychoacoustics. J Acoust Soc Am 49: 467–477. PLOS ONE | www.plosone.org 14 October 2012 | Volume 7 | Issue 10 | e46872