Spectral auditory integration and virtual cues to place-of-articulation in stops
Robert A. Fox, Marc Hamilton Smith, Ewa Jacewicz · The Journal of the Acoustical Society of America · 2006
The spectral ‘‘center-of-gravity’’ (COG) hypothesis proposed by Chistovich and colleagues for static vowels suggested spectral auditory integration of two or more formant peaks within 3.5 barks. More recently, studies have examined dynamic COG effects by modifying the amplitude of steady-state formants over time in order to create ‘‘virtual’’ diphthongs. The present study looks at ‘‘virtual frequency change’’ cues to the alveolar-velar place distinction in stops [an extension of Fox and Smith, J. Acoust. Soc. Am. 117, 2423 (2005)]. First, [d≳-g≳] and [t≳-k≳] series were synthesized with a 50-ms F3 transition (with a voiced or voiceless source). Next, matched stimulus series were created with virtual F3 transitions by changing the amplitudes of either a pair of sine waves (in [d≳]-[g≳]) or a pair of narrow band noise signals (in [t≳]-[k≳]) whose frequencies did not change. Another matched [t≳]-[k≳] series was produced with both actual and virtual stops bursts (with no F3 transitions). Identification of these stimulus series by listeners with normal hearing show that a dynamically changing COG in the initial 50 ms of the token can effectively cue place distinctions in stops as do formant transitions and bursts; however, virtual spectral cues are less salient than formant or burst cues. [Work supported by NIDCD R01DC00679-01A1.]