# Re: reverse engineering of acoustic sources (Helmholtz'shollowness)

Dear Giordano,

Thank you for your response. I have focused on wind instruments. Whereas the shape of their resonator is critical to the sound spectrum, the effect of wall vibration could be neglected. (This is not true for organ pipes and brass instruments.) So it has been hotly debated whether the material of woodwind instruments is critical to the timbre.

Of course, the problem is very different in the sounds of percussion instruments.

Best wishes,
Chen-Gia Tsai

DATE: Tue, 3 Feb 2004 10:54:55
From: Giordano Bruno <bruno.giordano@UNIPD.IT>
To: AUDITORY@LISTS.MCGILL.CA
Cc:

>>Note that their sounds do not possess spectral features that can easily be
>>extracted for object identification. Hence, the majority of hollow objects
>>provide no distinct auditory cues worth learning for our cognitive system.
>
>I'd really be interested to understand on which basis the "easiness" of
>extraction of an auditory cue may be judged.
>Material categorization, and dissimilarity ratings of impulsive sounds have
>been shown to be influenced by a "complex" acoustical parameter called
>tan\phi [1] or \eta [2]. In the simpler version (tan\phi) this parameter may
>be roughly extracted averaging the damping factor of the spectral components
>(inverse of decay time), divided by half of their angular frequency.
>Now, although "simpler" acoustical parameters may explain the perceptual
>effects of this acoustical variable (spectral centroid, loudness decay
>velocity [2]), I wouldn't be completely sure about which is extracted more
>easily by the auditory system, simply because our knowledge may be
>incomplete.
>Please correct me if I'm wrong.
>     Bruno
>
>[1] Klatzky, R. L., Pai, D. K., & Krotkov, E. P. (2000). Perception of
>material from contact sounds. Presence: Teleoperators and Virtual
>Environment, 9 (4), 399-410.
>
>[2] McAdams, S., Chaigne, A., & Roussarie, V. The psychomecanics of
>simulated sound sources: Material properties of impacted bars. J. Acou. Soc.
>Am. In Press.
>
>~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>Bruno L. Giordano - Ph. D. student
>Dipartimento di Psicologia Generale
>Via Venezia 8 - 35131 Padova, Italy
>
>currently hosted by
>KTH - Royal Institute of Technology
>TMH - Department of Speech, Music and Hearing
>Drottning Kristinas v. 31
>SE-100 44 Stockholm, Sweden

____________________________________________________________
Get advanced SPAM filtering on Webmail or POP Mail ... Get Lycos Mail!