Application of loudness level to temporally varying sounds: In the case of sounds of musical performance

摘要

An application of loudness level to temporally varying sounds using sounds of musical performance that include line spectra was investigated. Twenty-six kinds of sound were used as stimuli. Stimuli No. 1 to No. 4 were 1/3 octave band noise with center frequency of 1 kHz. Timbre of tones of each stimulus was simulated to real musical instrument using a sound card on a computer. The stimuli were controlled with computer software and these stimuli included discrete frequency components. Stimuli No. 23 to 26 were the portions from orchestra music with continuous frequency components. The duration of the stimuli from No. 1 to No. 22 was about 3.3 s and that of the stimuli from No. 23 to 26 was about 10 s. The sounds were analyzed for each 1/3 octave band using a 1/3 octave band filter and the output levels were measured every 125 ms. The mean energy level of each 1/3 octave band was used as a representative value of temporal variation in the calculation of both loudness level based on ISO532B (LLz) and loudness level based on ANSI S3.4 (LLm).