The paper presents results of research on an influence of Temporary Threshold Shift (TTS) on the detection of changes in timbre of musical samples. The experiment was carried out with conditions that normally exist in a studio when sound material is recorded and mixed. The level of sound exposure that represents the noise signal is 90 dB, and this is an average value of sound level existing in control room. This musical material may be treated as a noise so TTS phenomenon may occur after several time durations: 60, 90, and 120 minutes. Ten subjects participated in the main part of the experiment and all of them have the normal hearing thresholds. The stimuli contained the musical material with introduced changes in timbre up to +/–6 dB in low (100 Hz), middle (1 kHz), and high frequency (10 kHz) regions. It turned out that listening to the music with an exposure of 90 dB for 1 hour influences the hearing thresholds for middle frequency region (about 1–2 kHz); and this has been reflected in a perception of timbre changes: after 1 hour listening the changes of spectrum in middle-frequencies region are perceived with a threshold of 3 dB while the changes of low and high ranges of spectrum were perceived with the thresholds of 1.8 and 1.5 dB, respectively. After the longer exposure, the thresholds shifted up to 3.5 dB for the all investigated stimuli.
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