|Motif||Name of motif||Composer||Source||Track||Ts||Td||te||[Dt1]p||[DTsub]p|
|2||Sinfonietta, Opus 48, IV||M.Arnold||1||2||0.0||6.3||54||21||1.2|
|3||Piano, Classical Mood||-||2||1||135.0||7.6||119||23||1.4|
|4||Female Chorus Standard||-||2||15||0.0||7.2||33||26||0.8|
|5||'Water Music' Suite VI||G.F. Handel||3||24||0.0||7.9||62||25||1.5|
|7||Marriage of Figaro Overture||W.A. Mozart||3||25||7.0||8.4||55||22||1.2|
|8||Flute, Classical Mood||-||3||31||0.0||8.1||40||32||1.0|
4.4. Examples of Individuals Subjective Preference by the Paired-Comparison Tests
Examples of the concert-goer's preferences
Figure 4.5 shows samples for measured preference curves of four subjects for the listening level parameter. This shows that the peak and curvature of the preference curves are individually different. This indicates that people have strong preferences concerning sound fields.
These results are stored into a file on the database for concert-goers. Then an individual ID card is issued.
Figure 4.5. Measured preference curves of four subjects for listening level.
4.5. Application of subjective
preference theory for a Seat selection system
A selection system was introduced to maximize the preference of each individual with respect to the sound field as described by the four acoustic factors. Preference tests were performed in a listening room simulating the sound fields with multiple loudspeakers installed in the Kirishima international concert hall. Suitable methods can be to use either the paired-comparison test or a method of adjustment by the listener, or a combined method that obtains the most preferred combination of LL, Dt1, and Tsub. To examine the preference as a function of the IACC, only the paired-comparison test is applicable, because a smaller value for the IACC is always preferable. Preference tests were performed using several music motifs. Since it is assumed here that there is no effect of the order of presentation, the test sound fields were tested using a total of thirty-three pairs, with five levels of LL, Dt1, Tsub, and three levels of IACC. The duration of each stimulus is about 10s. It takes about 15 minutes for each listener.
Scale values of individual preference as a function of each physical factor were obtained by the simplified method given in . An area of seats where individual preference is maximized can be found. The large individual differences in the most preferred listening level are at least partly related to the individual hearing level. The preferred initial time delay and the preferred reverberation time are associated with an individual preference for ''liveness". Generally, the preferred values of LL, Dt1, and Tsub for each individual are quite different, but all of the subjects tested always preferred a small value of IACC.
Examples of preference-test results for three individuals using Suite VI from the 'Water Music'' by G. F. Handel (te = 62ms) are shown in Figure 4.6. Listener A shows a preference similar to the global preference for each factor.
Figure 4.6. The results of preference tests and preferred seats graded into three levels: Listener A, B, C.
Listener B is recommended to sit close to the stage because he prefers a high
listening level. The listening level is designed to be nearly constant
throughout the hall; however, a large variation in the listening level may be
useful for meeting the large range of individual preferences in listening level.
Listener C is recommended to sit near the side walls because he prefers a short
initial time delay gap. The preferred value of each physical factor is very
different. The range of preferred listening level, for example, is much greater
than 20 dB (A) due to the individual difference of the hearing level. With
regard to the reverberation time, the range of preferred value is 0.5-4.5 s .
The initial time delay gap also has a great range of preferred value. To
maximize the individual preference, such facts must be considered.
The results of the preference tests for each individual have been discussed in terms of the inter-individual differences . The investigation shows that subjects with small inter-individual difference have critical preferred value indicating large values of ai in equation (6), chapter 1. On the other hand, the preferred listening level for the subjects with small values of ai are barely determined.
The individual subjective preference may be met using the seat-selection system based on the four orthogonal physical factors of the sound field for each seat. Examples of scale values obtained by preference tests and the results of seat selection to maximize individual preference are demonstrated.