Quantification of the Tonal Prominence of Complex Tones in Machinery Noise

This paper describes how many of the sounds that are usually heard evoke pitch sensation. A singing voice, speech and the sounds of various musical instruments are some of examples. In general, those sounds are composed of many harmonic or inharmonic tones but they can produce a pitch sensation as a whole, known as “virtual pitch” or “residue pitch”. For an engineering point of view, it is important to measure the strength of the pitch sensation quantitatively. Metrics like Tone-to-Noise Ratio, Prominence Ratio and Aures’ Tonality only measure the tonal prominence of individual tones, so these metrics are not appropriate to be used for harmonic complex signals. Various models have been proposed in this paper to explain the mechanism of the pitch perception of complex tones. Those models can be largely divided into two large categories based on pattern recognition theory and temporal theory. In pattern recognition theory it is assumed that the pitch of a complex tone is derived by a central processor which uses neural signals generated by individual tonal components as inputs. On the other hand, in temporal theory it is assumed that the pitch perception is related to the time intervals between nerve firings evoked by the sound stimulus. The spectral-pitch pattern (SP pattern) and the virtual-pitch pattern (VP pattern) are the outputs of the algorithm. The SP pattern represents the pitch sensation directly related to the spectral shape of a complex tone, whereas the VP pattern is derived from the SP pattern by a process called “subharmonic coincidence assessment”. The application of interest is noise in cabs of large earth moving machinery which can contain several harmonic families. A robust signal processing algorithm has been written to automatically detect the families of tones given some basic information on the diesel engine characteristics. The next stage is to process this information to predict the strength of perceived pitch or pitches that are associated with these families. As a first step in addressing this challenging problem, some preliminary work examining the utility model for analyzing one harmonic tone complex combined with an additional single tone has been conducted. A series of subjective experiments are described below and the results are compared to predictions.

Language

  • English

Media Info

  • Media Type: CD-ROM
  • Features: Figures; References;
  • Pagination: pp 169-174
  • Monograph Title: Noise-Con 04. The 2004 National Conference on Noise Control Engineering

Subject/Index Terms

Filing Info

  • Accession Number: 01053799
  • Record Type: Publication
  • Files: TRIS, TRB
  • Created Date: Jul 13 2007 1:17PM